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Merge pull request #65165 from Blargian/fix_deadlinks
Fix broken links in docs
This commit is contained in:
Yarik Briukhovetskyi
GitHub
commit
f811dbf8f8
@ -106,8 +106,8 @@ To work with these states, use:
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- [AggregatingMergeTree](../../engines/table-engines/mergetree-family/aggregatingmergetree.md) table engine.
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- [finalizeAggregation](../../sql-reference/functions/other-functions.md#function-finalizeaggregation) function.
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- [runningAccumulate](../../sql-reference/functions/other-functions.md#runningaccumulate) function.
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- [-Merge](#aggregate_functions_combinators-merge) combinator.
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- [-MergeState](#aggregate_functions_combinators-mergestate) combinator.
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- [-Merge](#-merge) combinator.
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- [-MergeState](#-mergestate) combinator.
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## -Merge
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@ -82,10 +82,12 @@ FROM
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In this case, you should remember that you do not know the histogram bin borders.
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## sequenceMatch(pattern)(timestamp, cond1, cond2, ...)
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## sequenceMatch
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Checks whether the sequence contains an event chain that matches the pattern.
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**Syntax**
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``` sql
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sequenceMatch(pattern)(timestamp, cond1, cond2, ...)
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```
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@ -102,7 +104,7 @@ Events that occur at the same second may lay in the sequence in an undefined ord
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**Parameters**
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- `pattern` — Pattern string. See [Pattern syntax](#sequence-function-pattern-syntax).
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- `pattern` — Pattern string. See [Pattern syntax](#sequencematch).
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**Returned values**
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@ -170,9 +172,9 @@ SELECT sequenceMatch('(?1)(?2)')(time, number = 1, number = 2, number = 4) FROM
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**See Also**
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- [sequenceCount](#function-sequencecount)
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- [sequenceCount](#sequencecount)
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## sequenceCount(pattern)(time, cond1, cond2, ...)
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## sequenceCount
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Counts the number of event chains that matched the pattern. The function searches event chains that do not overlap. It starts to search for the next chain after the current chain is matched.
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@ -180,6 +182,8 @@ Counts the number of event chains that matched the pattern. The function searche
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Events that occur at the same second may lay in the sequence in an undefined order affecting the result.
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:::
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**Syntax**
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``` sql
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sequenceCount(pattern)(timestamp, cond1, cond2, ...)
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```
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@ -192,7 +196,7 @@ sequenceCount(pattern)(timestamp, cond1, cond2, ...)
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**Parameters**
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- `pattern` — Pattern string. See [Pattern syntax](#sequence-function-pattern-syntax).
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- `pattern` — Pattern string. See [Pattern syntax](#sequencematch).
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**Returned values**
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@ -229,7 +233,7 @@ SELECT sequenceCount('(?1).*(?2)')(time, number = 1, number = 2) FROM t
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**See Also**
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- [sequenceMatch](#function-sequencematch)
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- [sequenceMatch](#sequencematch)
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## windowFunnel
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@ -3,7 +3,7 @@ slug: /en/sql-reference/aggregate-functions/reference/stochasticlinearregression
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sidebar_position: 221
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---
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# stochasticLinearRegression
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# stochasticLinearRegression {#agg_functions_stochasticlinearregression_parameters}
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This function implements stochastic linear regression. It supports custom parameters for learning rate, L2 regularization coefficient, mini-batch size, and has a few methods for updating weights ([Adam](https://en.wikipedia.org/wiki/Stochastic_gradient_descent#Adam) (used by default), [simple SGD](https://en.wikipedia.org/wiki/Stochastic_gradient_descent), [Momentum](https://en.wikipedia.org/wiki/Stochastic_gradient_descent#Momentum), and [Nesterov](https://mipt.ru/upload/medialibrary/d7e/41-91.pdf)).
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@ -72,5 +72,5 @@ The query will return a column of predicted values. Note that first argument of
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**See Also**
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- [stochasticLogisticRegression](../../../sql-reference/aggregate-functions/reference/stochasticlogisticregression.md#agg_functions-stochasticlogisticregression)
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- [stochasticLogisticRegression](../../../sql-reference/aggregate-functions/reference/stochasticlogisticregression.md#stochasticlogisticregression)
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- [Difference between linear and logistic regressions](https://stackoverflow.com/questions/12146914/what-is-the-difference-between-linear-regression-and-logistic-regression)
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@ -11,7 +11,7 @@ This function implements stochastic logistic regression. It can be used for bina
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Parameters are exactly the same as in stochasticLinearRegression:
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`learning rate`, `l2 regularization coefficient`, `mini-batch size`, `method for updating weights`.
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For more information see [parameters](#agg_functions-stochasticlinearregression-parameters).
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For more information see [parameters](../reference/stochasticlinearregression.md/#parameters).
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``` text
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stochasticLogisticRegression(1.0, 1.0, 10, 'SGD')
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@ -27,7 +27,7 @@ Returns an integer of type `Float64`.
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**Implementation details**
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This function uses a numerically unstable algorithm. If you need numerical stability in calculations, use the slower but more stable [`varPopStable` function](#varPopStable).
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This function uses a numerically unstable algorithm. If you need numerical stability in calculations, use the slower but more stable [`varPopStable`](#varpopstable) function.
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**Example**
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@ -76,7 +76,7 @@ Returns an integer of type `Float64`.
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**Implementation details**
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Unlike [`varPop()`](#varPop), this function uses a stable, numerically accurate algorithm to calculate the population variance to avoid issues like catastrophic cancellation or loss of precision. This function also handles `NaN` and `Inf` values correctly, excluding them from calculations.
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Unlike [`varPop`](#varpop), this function uses a stable, numerically accurate algorithm to calculate the population variance to avoid issues like catastrophic cancellation or loss of precision. This function also handles `NaN` and `Inf` values correctly, excluding them from calculations.
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**Example**
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@ -40,7 +40,7 @@ Where:
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The function assumes that the input data set represents a sample from a larger population. If you want to calculate the variance of the entire population (when you have the complete data set), you should use the [`varPop()` function](./varpop#varpop) instead.
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This function uses a numerically unstable algorithm. If you need numerical stability in calculations, use the slower but more stable [`varSampStable` function](#varSampStable).
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This function uses a numerically unstable algorithm. If you need numerical stability in calculations, use the slower but more stable [`varSampStable`](#varsampstable) function.
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**Example**
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@ -82,11 +82,11 @@ varSampStable(expr)
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**Returned value**
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The `varSampStable()` function returns a Float64 value representing the sample variance of the input data set.
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The `varSampStable` function returns a Float64 value representing the sample variance of the input data set.
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**Implementation details**
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The `varSampStable()` function calculates the sample variance using the same formula as the [`varSamp()`](#varSamp function):
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The `varSampStable` function calculates the sample variance using the same formula as the [`varSamp`](#varsamp) function:
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```plaintext
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∑(x - mean(x))^2 / (n - 1)
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@ -97,9 +97,9 @@ Where:
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- `mean(x)` is the arithmetic mean of the data set.
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- `n` is the number of data points in the data set.
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The difference between `varSampStable()` and `varSamp()` is that `varSampStable()` is designed to provide a more deterministic and stable result when dealing with floating-point arithmetic. It uses an algorithm that minimizes the accumulation of rounding errors, which can be particularly important when dealing with large data sets or data with a wide range of values.
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The difference between `varSampStable` and `varSamp` is that `varSampStable` is designed to provide a more deterministic and stable result when dealing with floating-point arithmetic. It uses an algorithm that minimizes the accumulation of rounding errors, which can be particularly important when dealing with large data sets or data with a wide range of values.
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Like `varSamp()`, the `varSampStable()` function assumes that the input data set represents a sample from a larger population. If you want to calculate the variance of the entire population (when you have the complete data set), you should use the [`varPopStable()` function](./varpop#varpopstable) instead.
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Like `varSamp`, the `varSampStable` function assumes that the input data set represents a sample from a larger population. If you want to calculate the variance of the entire population (when you have the complete data set), you should use the [`varPopStable`](./varpop#varpopstable) function instead.
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**Example**
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@ -125,4 +125,4 @@ Response:
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0.865
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```
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This query calculates the sample variance of the `value` column in the `example_table` using the `varSampStable()` function. The result shows that the sample variance of the values `[10.5, 12.3, 9.8, 11.2, 10.7]` is approximately 0.865, which may differ slightly from the result of `varSamp()` due to the more precise handling of floating-point arithmetic.
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This query calculates the sample variance of the `value` column in the `example_table` using the `varSampStable()` function. The result shows that the sample variance of the values `[10.5, 12.3, 9.8, 11.2, 10.7]` is approximately 0.865, which may differ slightly from the result of `varSamp` due to the more precise handling of floating-point arithmetic.
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@ -33,7 +33,7 @@ Result:
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## Ring
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`Ring` is a simple polygon without holes stored as an array of points: [Array](array.md)([Point](#point-data-type)).
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`Ring` is a simple polygon without holes stored as an array of points: [Array](array.md)([Point](#point)).
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**Example**
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@ -54,7 +54,7 @@ Result:
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## Polygon
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`Polygon` is a polygon with holes stored as an array of rings: [Array](array.md)([Ring](#ring-data-type)). First element of outer array is the outer shape of polygon and all the following elements are holes.
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`Polygon` is a polygon with holes stored as an array of rings: [Array](array.md)([Ring](#ring)). First element of outer array is the outer shape of polygon and all the following elements are holes.
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**Example**
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@ -76,7 +76,7 @@ Result:
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## MultiPolygon
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`MultiPolygon` consists of multiple polygons and is stored as an array of polygons: [Array](array.md)([Polygon](#polygon-data-type)).
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`MultiPolygon` consists of multiple polygons and is stored as an array of polygons: [Array](array.md)([Polygon](#polygon)).
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**Example**
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@ -16,7 +16,7 @@ ClickHouse supports special functions for working with dictionaries that can be
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ClickHouse supports:
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- Dictionaries with a [set of functions](../../sql-reference/functions/ext-dict-functions.md).
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- [Embedded dictionaries](#embedded_dictionaries) with a specific [set of functions](../../sql-reference/functions/ym-dict-functions.md).
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- [Embedded dictionaries](#embedded-dictionaries) with a specific [set of functions](../../sql-reference/functions/ym-dict-functions.md).
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:::tip Tutorial
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@ -82,7 +82,7 @@ You can [configure](#configuring-a-dictionary) any number of dictionaries in the
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You can convert values for a small dictionary by describing it in a `SELECT` query (see the [transform](../../sql-reference/functions/other-functions.md) function). This functionality is not related to dictionaries.
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:::
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## Configuring a Dictionary {#configuring-a-dictionary}
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## Configuring a Dictionary
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<CloudDetails />
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@ -123,7 +123,7 @@ LAYOUT(...) -- Memory layout configuration
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LIFETIME(...) -- Lifetime of dictionary in memory
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```
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## Storing Dictionaries in Memory {#storing-dictionaries-in-memory}
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## Storing Dictionaries in Memory
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There are a variety of ways to store dictionaries in memory.
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@ -415,7 +415,7 @@ or
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LAYOUT(COMPLEX_KEY_HASHED_ARRAY([SHARDS 1]))
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```
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### range_hashed {#range_hashed}
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### range_hashed
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The dictionary is stored in memory in the form of a hash table with an ordered array of ranges and their corresponding values.
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@ -679,7 +679,7 @@ When searching for a dictionary, the cache is searched first. For each block of
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If keys are not found in dictionary, then update cache task is created and added into update queue. Update queue properties can be controlled with settings `max_update_queue_size`, `update_queue_push_timeout_milliseconds`, `query_wait_timeout_milliseconds`, `max_threads_for_updates`.
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For cache dictionaries, the expiration [lifetime](#dictionary-updates) of data in the cache can be set. If more time than `lifetime` has passed since loading the data in a cell, the cell’s value is not used and key becomes expired. The key is re-requested the next time it needs to be used. This behaviour can be configured with setting `allow_read_expired_keys`.
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For cache dictionaries, the expiration [lifetime](#refreshing-dictionary-data-using-lifetime) of data in the cache can be set. If more time than `lifetime` has passed since loading the data in a cell, the cell’s value is not used and key becomes expired. The key is re-requested the next time it needs to be used. This behaviour can be configured with setting `allow_read_expired_keys`.
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This is the least effective of all the ways to store dictionaries. The speed of the cache depends strongly on correct settings and the usage scenario. A cache type dictionary performs well only when the hit rates are high enough (recommended 99% and higher). You can view the average hit rate in the [system.dictionaries](../../operations/system-tables/dictionaries.md) table.
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@ -899,7 +899,7 @@ Other types are not supported yet. The function returns the attribute for the pr
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|
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Data must completely fit into RAM.
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## Refreshing dictionary data using LIFETIME {#lifetime}
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## Refreshing dictionary data using LIFETIME
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ClickHouse periodically updates dictionaries based on the `LIFETIME` tag (defined in seconds). `LIFETIME` is the update interval for fully downloaded dictionaries and the invalidation interval for cached dictionaries.
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@ -1031,7 +1031,7 @@ SOURCE(CLICKHOUSE(... update_field 'added_time' update_lag 15))
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...
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```
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## Dictionary Sources {#dictionary-sources}
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## Dictionary Sources
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||||
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<CloudDetails />
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|
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@ -1065,7 +1065,7 @@ SOURCE(SOURCE_TYPE(param1 val1 ... paramN valN)) -- Source configuration
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The source is configured in the `source` section.
|
||||
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For source types [Local file](#local_file), [Executable file](#executable), [HTTP(s)](#https), [ClickHouse](#clickhouse)
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For source types [Local file](#local-file), [Executable file](#executable-file), [HTTP(s)](#https), [ClickHouse](#clickhouse)
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||||
optional settings are available:
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||||
|
||||
``` xml
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@ -1089,10 +1089,10 @@ SETTINGS(format_csv_allow_single_quotes = 0)
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||||
|
||||
Types of sources (`source_type`):
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||||
- [Local file](#local_file)
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- [Executable File](#executable)
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- [Executable Pool](#executable_pool)
|
||||
- [HTTP(S)](#http)
|
||||
- [Local file](#local-file)
|
||||
- [Executable File](#executable-file)
|
||||
- [Executable Pool](#executable-pool)
|
||||
- [HTTP(S)](#https)
|
||||
- DBMS
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||||
- [ODBC](#odbc)
|
||||
- [MySQL](#mysql)
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@ -1102,7 +1102,7 @@ Types of sources (`source_type`):
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- [Cassandra](#cassandra)
|
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- [PostgreSQL](#postgresql)
|
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|
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### Local File {#local_file}
|
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### Local File
|
||||
|
||||
Example of settings:
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|
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@ -1132,9 +1132,9 @@ When a dictionary with source `FILE` is created via DDL command (`CREATE DICTION
|
||||
|
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- [Dictionary function](../../sql-reference/table-functions/dictionary.md#dictionary-function)
|
||||
|
||||
### Executable File {#executable}
|
||||
### Executable File
|
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|
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Working with executable files depends on [how the dictionary is stored in memory](#storig-dictionaries-in-memory). If the dictionary is stored using `cache` and `complex_key_cache`, ClickHouse requests the necessary keys by sending a request to the executable file’s STDIN. Otherwise, ClickHouse starts the executable file and treats its output as dictionary data.
|
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Working with executable files depends on [how the dictionary is stored in memory](#storing-dictionaries-in-memory). If the dictionary is stored using `cache` and `complex_key_cache`, ClickHouse requests the necessary keys by sending a request to the executable file’s STDIN. Otherwise, ClickHouse starts the executable file and treats its output as dictionary data.
|
||||
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Example of settings:
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@ -1161,7 +1161,7 @@ Setting fields:
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|
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That dictionary source can be configured only via XML configuration. Creating dictionaries with executable source via DDL is disabled; otherwise, the DB user would be able to execute arbitrary binaries on the ClickHouse node.
|
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|
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### Executable Pool {#executable_pool}
|
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### Executable Pool
|
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|
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Executable pool allows loading data from pool of processes. This source does not work with dictionary layouts that need to load all data from source. Executable pool works if the dictionary [is stored](#ways-to-store-dictionaries-in-memory) using `cache`, `complex_key_cache`, `ssd_cache`, `complex_key_ssd_cache`, `direct`, or `complex_key_direct` layouts.
|
||||
|
||||
@ -1196,9 +1196,9 @@ Setting fields:
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||||
|
||||
That dictionary source can be configured only via XML configuration. Creating dictionaries with executable source via DDL is disabled, otherwise, the DB user would be able to execute arbitrary binary on ClickHouse node.
|
||||
|
||||
### HTTP(S) {#https}
|
||||
### HTTP(S)
|
||||
|
||||
Working with an HTTP(S) server depends on [how the dictionary is stored in memory](#storig-dictionaries-in-memory). If the dictionary is stored using `cache` and `complex_key_cache`, ClickHouse requests the necessary keys by sending a request via the `POST` method.
|
||||
Working with an HTTP(S) server depends on [how the dictionary is stored in memory](#storing-dictionaries-in-memory). If the dictionary is stored using `cache` and `complex_key_cache`, ClickHouse requests the necessary keys by sending a request via the `POST` method.
|
||||
|
||||
Example of settings:
|
||||
|
||||
@ -1285,7 +1285,7 @@ Setting fields:
|
||||
- `db` – Name of the database. Omit it if the database name is set in the `<connection_string>` parameters.
|
||||
- `table` – Name of the table and schema if exists.
|
||||
- `connection_string` – Connection string.
|
||||
- `invalidate_query` – Query for checking the dictionary status. Optional parameter. Read more in the section [Updating dictionaries](#dictionary-updates).
|
||||
- `invalidate_query` – Query for checking the dictionary status. Optional parameter. Read more in the section [Refreshing dictionary data using LIFETIME](#refreshing-dictionary-data-using-lifetime).
|
||||
- `query` – The custom query. Optional parameter.
|
||||
|
||||
:::note
|
||||
@ -1575,7 +1575,7 @@ Setting fields:
|
||||
|
||||
- `where` – The selection criteria. The syntax for conditions is the same as for `WHERE` clause in MySQL, for example, `id > 10 AND id < 20`. Optional parameter.
|
||||
|
||||
- `invalidate_query` – Query for checking the dictionary status. Optional parameter. Read more in the section [Updating dictionaries](#dictionary-updates).
|
||||
- `invalidate_query` – Query for checking the dictionary status. Optional parameter. Read more in the section [Refreshing dictionary data using LIFETIME](#refreshing-dictionary-data-using-lifetime).
|
||||
|
||||
- `fail_on_connection_loss` – The configuration parameter that controls behavior of the server on connection loss. If `true`, an exception is thrown immediately if the connection between client and server was lost. If `false`, the ClickHouse server retries to execute the query three times before throwing an exception. Note that retrying leads to increased response times. Default value: `false`.
|
||||
|
||||
@ -1672,7 +1672,7 @@ Setting fields:
|
||||
- `db` – Name of the database.
|
||||
- `table` – Name of the table.
|
||||
- `where` – The selection criteria. May be omitted.
|
||||
- `invalidate_query` – Query for checking the dictionary status. Optional parameter. Read more in the section [Updating dictionaries](#dictionary-updates).
|
||||
- `invalidate_query` – Query for checking the dictionary status. Optional parameter. Read more in the section [Refreshing dictionary data using LIFETIME](#refreshing-dictionary-data-using-lifetime).
|
||||
- `secure` - Use ssl for connection.
|
||||
- `query` – The custom query. Optional parameter.
|
||||
|
||||
@ -1849,7 +1849,7 @@ Setting fields:
|
||||
- `db` – Name of the database.
|
||||
- `table` – Name of the table.
|
||||
- `where` – The selection criteria. The syntax for conditions is the same as for `WHERE` clause in PostgreSQL. For example, `id > 10 AND id < 20`. Optional parameter.
|
||||
- `invalidate_query` – Query for checking the dictionary status. Optional parameter. Read more in the section [Updating dictionaries](#dictionary-updates).
|
||||
- `invalidate_query` – Query for checking the dictionary status. Optional parameter. Read more in the section [Refreshing dictionary data using LIFETIME](#refreshing-dictionary-data-using-lifetime).
|
||||
- `query` – The custom query. Optional parameter.
|
||||
|
||||
:::note
|
||||
@ -1873,7 +1873,7 @@ LAYOUT(FLAT())
|
||||
LIFETIME(0);
|
||||
```
|
||||
|
||||
## Dictionary Key and Fields {#dictionary-key-and-fields}
|
||||
## Dictionary Key and Fields
|
||||
|
||||
<CloudDetails />
|
||||
|
||||
@ -1963,7 +1963,7 @@ PRIMARY KEY Id
|
||||
|
||||
### Composite Key
|
||||
|
||||
The key can be a `tuple` from any types of fields. The [layout](#storig-dictionaries-in-memory) in this case must be `complex_key_hashed` or `complex_key_cache`.
|
||||
The key can be a `tuple` from any types of fields. The [layout](#storing-dictionaries-in-memory) in this case must be `complex_key_hashed` or `complex_key_cache`.
|
||||
|
||||
:::tip
|
||||
A composite key can consist of a single element. This makes it possible to use a string as the key, for instance.
|
||||
@ -2030,17 +2030,17 @@ CREATE DICTIONARY somename (
|
||||
|
||||
Configuration fields:
|
||||
|
||||
| Tag | Description | Required |
|
||||
|------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------|
|
||||
| `name` | Column name. | Yes |
|
||||
| `type` | ClickHouse data type: [UInt8](../../sql-reference/data-types/int-uint.md), [UInt16](../../sql-reference/data-types/int-uint.md), [UInt32](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md), [Int8](../../sql-reference/data-types/int-uint.md), [Int16](../../sql-reference/data-types/int-uint.md), [Int32](../../sql-reference/data-types/int-uint.md), [Int64](../../sql-reference/data-types/int-uint.md), [Float32](../../sql-reference/data-types/float.md), [Float64](../../sql-reference/data-types/float.md), [UUID](../../sql-reference/data-types/uuid.md), [Decimal32](../../sql-reference/data-types/decimal.md), [Decimal64](../../sql-reference/data-types/decimal.md), [Decimal128](../../sql-reference/data-types/decimal.md), [Decimal256](../../sql-reference/data-types/decimal.md),[Date](../../sql-reference/data-types/date.md), [Date32](../../sql-reference/data-types/date32.md), [DateTime](../../sql-reference/data-types/datetime.md), [DateTime64](../../sql-reference/data-types/datetime64.md), [String](../../sql-reference/data-types/string.md), [Array](../../sql-reference/data-types/array.md).<br/>ClickHouse tries to cast value from dictionary to the specified data type. For example, for MySQL, the field might be `TEXT`, `VARCHAR`, or `BLOB` in the MySQL source table, but it can be uploaded as `String` in ClickHouse.<br/>[Nullable](../../sql-reference/data-types/nullable.md) is currently supported for [Flat](#flat), [Hashed](#hashed), [ComplexKeyHashed](#complex_key_hashed), [Direct](#direct), [ComplexKeyDirect](#complex_key_direct), [RangeHashed](#range_hashed), Polygon, [Cache](#cache), [ComplexKeyCache](#complex_key_cache), [SSDCache](#ssd_cache), [SSDComplexKeyCache](#complex_key_ssd_cache) dictionaries. In [IPTrie](#ip_trie) dictionaries `Nullable` types are not supported. | Yes |
|
||||
| `null_value` | Default value for a non-existing element.<br/>In the example, it is an empty string. [NULL](../syntax.md#null) value can be used only for the `Nullable` types (see the previous line with types description). | Yes |
|
||||
| `expression` | [Expression](../../sql-reference/syntax.md#expressions) that ClickHouse executes on the value.<br/>The expression can be a column name in the remote SQL database. Thus, you can use it to create an alias for the remote column.<br/><br/>Default value: no expression. | No |
|
||||
| <a name="hierarchical-dict-attr"></a> `hierarchical` | If `true`, the attribute contains the value of a parent key for the current key. See [Hierarchical Dictionaries](#hierarchical-dictionaries).<br/><br/>Default value: `false`. | No |
|
||||
| `injective` | Flag that shows whether the `id -> attribute` image is [injective](https://en.wikipedia.org/wiki/Injective_function).<br/>If `true`, ClickHouse can automatically place after the `GROUP BY` clause the requests to dictionaries with injection. Usually it significantly reduces the amount of such requests.<br/><br/>Default value: `false`. | No |
|
||||
| `is_object_id` | Flag that shows whether the query is executed for a MongoDB document by `ObjectID`.<br/><br/>Default value: `false`.
|
||||
| Tag | Description | Required |
|
||||
|------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------|
|
||||
| `name` | Column name. | Yes |
|
||||
| `type` | ClickHouse data type: [UInt8](../../sql-reference/data-types/int-uint.md), [UInt16](../../sql-reference/data-types/int-uint.md), [UInt32](../../sql-reference/data-types/int-uint.md), [UInt64](../../sql-reference/data-types/int-uint.md), [Int8](../../sql-reference/data-types/int-uint.md), [Int16](../../sql-reference/data-types/int-uint.md), [Int32](../../sql-reference/data-types/int-uint.md), [Int64](../../sql-reference/data-types/int-uint.md), [Float32](../../sql-reference/data-types/float.md), [Float64](../../sql-reference/data-types/float.md), [UUID](../../sql-reference/data-types/uuid.md), [Decimal32](../../sql-reference/data-types/decimal.md), [Decimal64](../../sql-reference/data-types/decimal.md), [Decimal128](../../sql-reference/data-types/decimal.md), [Decimal256](../../sql-reference/data-types/decimal.md),[Date](../../sql-reference/data-types/date.md), [Date32](../../sql-reference/data-types/date32.md), [DateTime](../../sql-reference/data-types/datetime.md), [DateTime64](../../sql-reference/data-types/datetime64.md), [String](../../sql-reference/data-types/string.md), [Array](../../sql-reference/data-types/array.md).<br/>ClickHouse tries to cast value from dictionary to the specified data type. For example, for MySQL, the field might be `TEXT`, `VARCHAR`, or `BLOB` in the MySQL source table, but it can be uploaded as `String` in ClickHouse.<br/>[Nullable](../../sql-reference/data-types/nullable.md) is currently supported for [Flat](#flat), [Hashed](#hashed), [ComplexKeyHashed](#complex_key_hashed), [Direct](#direct), [ComplexKeyDirect](#complex_key_direct), [RangeHashed](#range_hashed), Polygon, [Cache](#cache), [ComplexKeyCache](#complex_key_cache), [SSDCache](#ssd_cache), [SSDComplexKeyCache](#complex_key_ssd_cache) dictionaries. In [IPTrie](#ip_trie) dictionaries `Nullable` types are not supported. | Yes |
|
||||
| `null_value` | Default value for a non-existing element.<br/>In the example, it is an empty string. [NULL](../syntax.md#null) value can be used only for the `Nullable` types (see the previous line with types description). | Yes |
|
||||
| `expression` | [Expression](../../sql-reference/syntax.md#expressions) that ClickHouse executes on the value.<br/>The expression can be a column name in the remote SQL database. Thus, you can use it to create an alias for the remote column.<br/><br/>Default value: no expression. | No |
|
||||
| <a name="hierarchical-dict-attr"></a> `hierarchical` | If `true`, the attribute contains the value of a parent key for the current key. See [Hierarchical Dictionaries](#hierarchical-dictionaries).<br/><br/>Default value: `false`. | No |
|
||||
| `injective` | Flag that shows whether the `id -> attribute` image is [injective](https://en.wikipedia.org/wiki/Injective_function).<br/>If `true`, ClickHouse can automatically place after the `GROUP BY` clause the requests to dictionaries with injection. Usually it significantly reduces the amount of such requests.<br/><br/>Default value: `false`. | No |
|
||||
| `is_object_id` | Flag that shows whether the query is executed for a MongoDB document by `ObjectID`.<br/><br/>Default value: `false`.
|
||||
|
||||
## Hierarchical Dictionaries {#hierarchical-dictionaries}
|
||||
## Hierarchical Dictionaries
|
||||
|
||||
ClickHouse supports hierarchical dictionaries with a [numeric key](#numeric-key).
|
||||
|
||||
@ -2165,7 +2165,7 @@ Points can be specified as an array or a tuple of their coordinates. In the curr
|
||||
|
||||
The user can upload their own data in all formats supported by ClickHouse.
|
||||
|
||||
There are 3 types of [in-memory storage](#storig-dictionaries-in-memory) available:
|
||||
There are 3 types of [in-memory storage](#storing-dictionaries-in-memory) available:
|
||||
|
||||
- `POLYGON_SIMPLE`. This is a naive implementation, where a linear pass through all polygons is made for each query, and membership is checked for each one without using additional indexes.
|
||||
|
||||
@ -2435,7 +2435,7 @@ LIFETIME(0)
|
||||
LAYOUT(regexp_tree);
|
||||
```
|
||||
|
||||
## Embedded Dictionaries {#embedded-dictionaries}
|
||||
## Embedded Dictionaries
|
||||
|
||||
<SelfManaged />
|
||||
|
||||
|
||||
@ -1261,7 +1261,7 @@ SELECT arraySort((x) -> -x, [1, 2, 3]) as res;
|
||||
└─────────┘
|
||||
```
|
||||
|
||||
For each element of the source array, the lambda function returns the sorting key, that is, \[1 –\> -1, 2 –\> -2, 3 –\> -3\]. Since the `arraySort` function sorts the keys in ascending order, the result is \[3, 2, 1\]. Thus, the `(x) –> -x` lambda function sets the [descending order](#reverse-sort) in a sorting.
|
||||
For each element of the source array, the lambda function returns the sorting key, that is, \[1 –\> -1, 2 –\> -2, 3 –\> -3\]. Since the `arraySort` function sorts the keys in ascending order, the result is \[3, 2, 1\]. Thus, the `(x) –> -x` lambda function sets the [descending order](#arrayreversesort) in a sorting.
|
||||
|
||||
The lambda function can accept multiple arguments. In this case, you need to pass the `arraySort` function several arrays of identical length that the arguments of lambda function will correspond to. The resulting array will consist of elements from the first input array; elements from the next input array(s) specify the sorting keys. For example:
|
||||
|
||||
@ -1307,10 +1307,15 @@ To improve sorting efficiency, the [Schwartzian transform](https://en.wikipedia.
|
||||
|
||||
Same as `arraySort` with additional `limit` argument allowing partial sorting. Returns an array of the same size as the original array where elements in range `[1..limit]` are sorted in ascending order. Remaining elements `(limit..N]` shall contain elements in unspecified order.
|
||||
|
||||
## arrayReverseSort(\[func,\] arr, ...) {#reverse-sort}
|
||||
## arrayReverseSort
|
||||
|
||||
Sorts the elements of the `arr` array in descending order. If the `func` function is specified, `arr` is sorted according to the result of the `func` function applied to the elements of the array, and then the sorted array is reversed. If `func` accepts multiple arguments, the `arrayReverseSort` function is passed several arrays that the arguments of `func` will correspond to. Detailed examples are shown at the end of `arrayReverseSort` description.
|
||||
|
||||
**Syntax**
|
||||
|
||||
```sql
|
||||
arrayReverseSort([func,] arr, ...)
|
||||
```
|
||||
Example of integer values sorting:
|
||||
|
||||
``` sql
|
||||
@ -1907,10 +1912,16 @@ FROM numbers(1,10);
|
||||
|
||||
- [arrayReduce](#arrayreduce)
|
||||
|
||||
## arrayReverse(arr)
|
||||
## arrayReverse
|
||||
|
||||
Returns an array of the same size as the original array containing the elements in reverse order.
|
||||
|
||||
**Syntax**
|
||||
|
||||
```sql
|
||||
arrayReverse(arr)
|
||||
```
|
||||
|
||||
Example:
|
||||
|
||||
``` sql
|
||||
|
||||
@ -74,7 +74,7 @@ bitmapSubsetInRange(bitmap, range_start, range_end)
|
||||
|
||||
**Arguments**
|
||||
|
||||
- `bitmap` – [Bitmap object](#bitmap_functions-bitmapbuild).
|
||||
- `bitmap` – [Bitmap object](#bitmapbuild).
|
||||
- `range_start` – Start of the range (inclusive). [UInt32](../data-types/int-uint.md).
|
||||
- `range_end` – End of the range (exclusive). [UInt32](../data-types/int-uint.md).
|
||||
|
||||
@ -104,7 +104,7 @@ bitmapSubsetLimit(bitmap, range_start, cardinality_limit)
|
||||
|
||||
**Arguments**
|
||||
|
||||
- `bitmap` – [Bitmap object](#bitmap_functions-bitmapbuild).
|
||||
- `bitmap` – [Bitmap object](#bitmapbuild).
|
||||
- `range_start` – Start of the range (inclusive). [UInt32](../data-types/int-uint.md).
|
||||
- `cardinality_limit` – Maximum cardinality of the subset. [UInt32](../data-types/int-uint.md).
|
||||
|
||||
@ -134,7 +134,7 @@ subBitmap(bitmap, offset, cardinality_limit)
|
||||
|
||||
**Arguments**
|
||||
|
||||
- `bitmap` – The bitmap. [Bitmap object](#bitmap_functions-bitmapbuild).
|
||||
- `bitmap` – The bitmap. [Bitmap object](#bitmapbuild).
|
||||
- `offset` – The position of the first element of the subset. [UInt32](../data-types/int-uint.md).
|
||||
- `cardinality_limit` – The maximum number of elements in the subset. [UInt32](../data-types/int-uint.md).
|
||||
|
||||
@ -162,7 +162,7 @@ bitmapContains(bitmap, needle)
|
||||
|
||||
**Arguments**
|
||||
|
||||
- `bitmap` – [Bitmap object](#bitmap_functions-bitmapbuild).
|
||||
- `bitmap` – [Bitmap object](#bitmapbuild).
|
||||
- `needle` – Searched bit value. [UInt32](../data-types/int-uint.md).
|
||||
|
||||
**Returned values**
|
||||
@ -188,7 +188,7 @@ Result:
|
||||
|
||||
Checks whether two bitmaps intersect.
|
||||
|
||||
If `bitmap2` contains exactly one element, consider using [bitmapContains](#bitmap_functions-bitmapcontains) instead as it works more efficiently.
|
||||
If `bitmap2` contains exactly one element, consider using [bitmapContains](#bitmapcontains) instead as it works more efficiently.
|
||||
|
||||
**Syntax**
|
||||
|
||||
|
||||
@ -83,7 +83,7 @@ Result:
|
||||
```
|
||||
## makeDate32
|
||||
|
||||
Like [makeDate](#makeDate) but produces a [Date32](../data-types/date32.md).
|
||||
Like [makeDate](#makedate) but produces a [Date32](../data-types/date32.md).
|
||||
|
||||
## makeDateTime
|
||||
|
||||
@ -214,7 +214,7 @@ Result:
|
||||
|
||||
**See also**
|
||||
|
||||
- [serverTimeZone](#serverTimeZone)
|
||||
- [serverTimeZone](#servertimezone)
|
||||
|
||||
## serverTimeZone
|
||||
|
||||
@ -249,7 +249,7 @@ Result:
|
||||
|
||||
**See also**
|
||||
|
||||
- [timeZone](#timeZone)
|
||||
- [timeZone](#timezone)
|
||||
|
||||
## toTimeZone
|
||||
|
||||
@ -305,7 +305,7 @@ int32samoa: 1546300800
|
||||
|
||||
**See Also**
|
||||
|
||||
- [formatDateTime](#formatDateTime) - supports non-constant timezone.
|
||||
- [formatDateTime](#formatdatetime) - supports non-constant timezone.
|
||||
- [toString](type-conversion-functions.md#tostring) - supports non-constant timezone.
|
||||
|
||||
## timeZoneOf
|
||||
@ -1006,7 +1006,7 @@ toStartOfWeek(t[, mode[, timezone]])
|
||||
**Arguments**
|
||||
|
||||
- `t` - a [Date](../data-types/date.md), [Date32](../data-types/date32.md), [DateTime](../data-types/datetime.md) or [DateTime64](../data-types/datetime64.md)
|
||||
- `mode` - determines the first day of the week as described in the [toWeek()](date-time-functions#toweek) function
|
||||
- `mode` - determines the first day of the week as described in the [toWeek()](#toweek) function
|
||||
- `timezone` - Optional parameter, it behaves like any other conversion function
|
||||
|
||||
**Returned value**
|
||||
@ -1049,7 +1049,7 @@ toLastDayOfWeek(t[, mode[, timezone]])
|
||||
**Arguments**
|
||||
|
||||
- `t` - a [Date](../data-types/date.md), [Date32](../data-types/date32.md), [DateTime](../data-types/datetime.md) or [DateTime64](../data-types/datetime64.md)
|
||||
- `mode` - determines the last day of the week as described in the [toWeek()](date-time-functions#toweek) function
|
||||
- `mode` - determines the last day of the week as described in the [toWeek](#toweek) function
|
||||
- `timezone` - Optional parameter, it behaves like any other conversion function
|
||||
|
||||
**Returned value**
|
||||
@ -1719,7 +1719,7 @@ Result:
|
||||
|
||||
**See Also**
|
||||
|
||||
- [fromDaysSinceYearZero](#fromDaysSinceYearZero)
|
||||
- [fromDaysSinceYearZero](#fromdayssinceyearzero)
|
||||
|
||||
## fromDaysSinceYearZero
|
||||
|
||||
@ -1759,11 +1759,11 @@ Result:
|
||||
|
||||
**See Also**
|
||||
|
||||
- [toDaysSinceYearZero](#toDaysSinceYearZero)
|
||||
- [toDaysSinceYearZero](#todayssinceyearzero)
|
||||
|
||||
## fromDaysSinceYearZero32
|
||||
|
||||
Like [fromDaysSinceYearZero](#fromDaysSinceYearZero) but returns a [Date32](../data-types/date32.md).
|
||||
Like [fromDaysSinceYearZero](#fromdayssinceyearzero) but returns a [Date32](../data-types/date32.md).
|
||||
|
||||
## age
|
||||
|
||||
@ -1982,7 +1982,7 @@ Result:
|
||||
|
||||
**See Also**
|
||||
|
||||
- [toStartOfInterval](#tostartofintervaldate_or_date_with_time-interval-x-unit--time_zone)
|
||||
- [toStartOfInterval](#tostartofinterval)
|
||||
|
||||
## date\_add
|
||||
|
||||
@ -2055,7 +2055,7 @@ Result:
|
||||
|
||||
**See Also**
|
||||
|
||||
- [addDate](#addDate)
|
||||
- [addDate](#adddate)
|
||||
|
||||
## date\_sub
|
||||
|
||||
@ -2129,7 +2129,7 @@ Result:
|
||||
|
||||
**See Also**
|
||||
|
||||
- [subDate](#subDate)
|
||||
- [subDate](#subdate)
|
||||
|
||||
## timestamp\_add
|
||||
|
||||
@ -2310,7 +2310,7 @@ Alias: `SUBDATE`
|
||||
|
||||
- [date_sub](#date_sub)
|
||||
|
||||
## now {#now}
|
||||
## now
|
||||
|
||||
Returns the current date and time at the moment of query analysis. The function is a constant expression.
|
||||
|
||||
@ -3609,7 +3609,7 @@ SELECT timeSlots(toDateTime64('1980-12-12 21:01:02.1234', 4, 'UTC'), toDecimal64
|
||||
└───────────────────────────────────────────────────────────────────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
## formatDateTime {#formatDateTime}
|
||||
## formatDateTime
|
||||
|
||||
Formats a Time according to the given Format string. Format is a constant expression, so you cannot have multiple formats for a single result column.
|
||||
|
||||
@ -3734,10 +3734,9 @@ LIMIT 10
|
||||
|
||||
**See Also**
|
||||
|
||||
- [formatDateTimeInJodaSyntax](##formatDateTimeInJodaSyntax)
|
||||
- [formatDateTimeInJodaSyntax](#formatdatetimeinjodasyntax)
|
||||
|
||||
|
||||
## formatDateTimeInJodaSyntax {#formatDateTimeInJodaSyntax}
|
||||
## formatDateTimeInJodaSyntax
|
||||
|
||||
Similar to formatDateTime, except that it formats datetime in Joda style instead of MySQL style. Refer to https://joda-time.sourceforge.net/apidocs/org/joda/time/format/DateTimeFormat.html.
|
||||
|
||||
@ -3902,11 +3901,11 @@ Result:
|
||||
|
||||
**See Also**
|
||||
|
||||
- [fromUnixTimestampInJodaSyntax](##fromUnixTimestampInJodaSyntax)
|
||||
- [fromUnixTimestampInJodaSyntax](#fromunixtimestampinjodasyntax)
|
||||
|
||||
## fromUnixTimestampInJodaSyntax
|
||||
|
||||
Same as [fromUnixTimestamp](#fromUnixTimestamp) but when called in the second way (two or three arguments), the formatting is performed using [Joda style](https://joda-time.sourceforge.net/apidocs/org/joda/time/format/DateTimeFormat.html) instead of MySQL style.
|
||||
Same as [fromUnixTimestamp](#fromunixtimestamp) but when called in the second way (two or three arguments), the formatting is performed using [Joda style](https://joda-time.sourceforge.net/apidocs/org/joda/time/format/DateTimeFormat.html) instead of MySQL style.
|
||||
|
||||
**Example:**
|
||||
|
||||
@ -4121,7 +4120,7 @@ Result:
|
||||
Returns the current date and time at the moment of query analysis. The function is a constant expression.
|
||||
|
||||
:::note
|
||||
This function gives the same result that `now('UTC')` would. It was added only for MySQL support and [`now`](#now-now) is the preferred usage.
|
||||
This function gives the same result that `now('UTC')` would. It was added only for MySQL support and [`now`](#now) is the preferred usage.
|
||||
:::
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -12,7 +12,7 @@ For dictionaries created with [DDL queries](../../sql-reference/statements/creat
|
||||
|
||||
For information on connecting and configuring dictionaries, see [Dictionaries](../../sql-reference/dictionaries/index.md).
|
||||
|
||||
## dictGet, dictGetOrDefault, dictGetOrNull {#dictGet}
|
||||
## dictGet, dictGetOrDefault, dictGetOrNull
|
||||
|
||||
Retrieves values from a dictionary.
|
||||
|
||||
|
||||
@ -4,6 +4,8 @@ sidebar_label: Geohash
|
||||
title: "Functions for Working with Geohash"
|
||||
---
|
||||
|
||||
## Geohash
|
||||
|
||||
[Geohash](https://en.wikipedia.org/wiki/Geohash) is the geocode system, which subdivides Earth’s surface into buckets of grid shape and encodes each cell into a short string of letters and digits. It is a hierarchical data structure, so the longer is the geohash string, the more precise is the geographic location.
|
||||
|
||||
If you need to manually convert geographic coordinates to geohash strings, you can use [geohash.org](http://geohash.org/).
|
||||
|
||||
@ -4,6 +4,8 @@ sidebar_label: H3 Indexes
|
||||
title: "Functions for Working with H3 Indexes"
|
||||
---
|
||||
|
||||
## H3 Index
|
||||
|
||||
[H3](https://eng.uber.com/h3/) is a geographical indexing system where Earth’s surface divided into a grid of even hexagonal cells. This system is hierarchical, i. e. each hexagon on the top level ("parent") can be split into seven even but smaller ones ("children"), and so on.
|
||||
|
||||
The level of the hierarchy is called `resolution` and can receive a value from `0` till `15`, where `0` is the `base` level with the largest and coarsest cells.
|
||||
@ -16,7 +18,7 @@ The full description of the H3 system is available at [the Uber Engineering site
|
||||
|
||||
## h3IsValid
|
||||
|
||||
Verifies whether the number is a valid [H3](#h3index) index.
|
||||
Verifies whether the number is a valid [H3](#h3-index) index.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -51,7 +53,7 @@ Result:
|
||||
|
||||
## h3GetResolution
|
||||
|
||||
Defines the resolution of the given [H3](#h3index) index.
|
||||
Defines the resolution of the given [H3](#h3-index) index.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -86,7 +88,7 @@ Result:
|
||||
|
||||
## h3EdgeAngle
|
||||
|
||||
Calculates the average length of the [H3](#h3index) hexagon edge in grades.
|
||||
Calculates the average length of the [H3](#h3-index) hexagon edge in grades.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -100,7 +102,7 @@ h3EdgeAngle(resolution)
|
||||
|
||||
**Returned values**
|
||||
|
||||
- The average length of the [H3](#h3index) hexagon edge in grades. [Float64](../../data-types/float.md).
|
||||
- The average length of the [H3](#h3-index) hexagon edge in grades. [Float64](../../data-types/float.md).
|
||||
|
||||
**Example**
|
||||
|
||||
@ -120,7 +122,7 @@ Result:
|
||||
|
||||
## h3EdgeLengthM
|
||||
|
||||
Calculates the average length of the [H3](#h3index) hexagon edge in meters.
|
||||
Calculates the average length of the [H3](#h3-index) hexagon edge in meters.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -134,7 +136,7 @@ h3EdgeLengthM(resolution)
|
||||
|
||||
**Returned values**
|
||||
|
||||
- The average length of the [H3](#h3index) hexagon edge in meters. [Float64](../../data-types/float.md).
|
||||
- The average length of the [H3](#h3-index) hexagon edge in meters. [Float64](../../data-types/float.md).
|
||||
|
||||
**Example**
|
||||
|
||||
@ -154,7 +156,7 @@ Result:
|
||||
|
||||
## h3EdgeLengthKm
|
||||
|
||||
Calculates the average length of the [H3](#h3index) hexagon edge in kilometers.
|
||||
Calculates the average length of the [H3](#h3-index) hexagon edge in kilometers.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -168,7 +170,7 @@ h3EdgeLengthKm(resolution)
|
||||
|
||||
**Returned values**
|
||||
|
||||
- The average length of the [H3](#h3index) hexagon edge in kilometers. [Float64](../../data-types/float.md).
|
||||
- The average length of the [H3](#h3-index) hexagon edge in kilometers. [Float64](../../data-types/float.md).
|
||||
|
||||
**Example**
|
||||
|
||||
@ -188,7 +190,7 @@ Result:
|
||||
|
||||
## geoToH3
|
||||
|
||||
Returns [H3](#h3index) point index `(lon, lat)` with specified resolution.
|
||||
Returns [H3](#h3-index) point index `(lon, lat)` with specified resolution.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -225,7 +227,7 @@ Result:
|
||||
|
||||
## h3ToGeo
|
||||
|
||||
Returns the centroid longitude and latitude corresponding to the provided [H3](#h3index) index.
|
||||
Returns the centroid longitude and latitude corresponding to the provided [H3](#h3-index) index.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -294,7 +296,7 @@ Result:
|
||||
|
||||
## h3kRing
|
||||
|
||||
Lists all the [H3](#h3index) hexagons in the raduis of `k` from the given hexagon in random order.
|
||||
Lists all the [H3](#h3-index) hexagons in the raduis of `k` from the given hexagon in random order.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -335,7 +337,7 @@ Result:
|
||||
|
||||
## h3GetBaseCell
|
||||
|
||||
Returns the base cell number of the [H3](#h3index) index.
|
||||
Returns the base cell number of the [H3](#h3-index) index.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -437,7 +439,7 @@ Result:
|
||||
|
||||
## h3IndexesAreNeighbors
|
||||
|
||||
Returns whether or not the provided [H3](#h3index) indexes are neighbors.
|
||||
Returns whether or not the provided [H3](#h3-index) indexes are neighbors.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -473,7 +475,7 @@ Result:
|
||||
|
||||
## h3ToChildren
|
||||
|
||||
Returns an array of child indexes for the given [H3](#h3index) index.
|
||||
Returns an array of child indexes for the given [H3](#h3-index) index.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -508,7 +510,7 @@ Result:
|
||||
|
||||
## h3ToParent
|
||||
|
||||
Returns the parent (coarser) index containing the given [H3](#h3index) index.
|
||||
Returns the parent (coarser) index containing the given [H3](#h3-index) index.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -609,7 +611,7 @@ Result:
|
||||
|
||||
## h3GetResolution
|
||||
|
||||
Returns the resolution of the [H3](#h3index) index.
|
||||
Returns the resolution of the [H3](#h3-index) index.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -643,7 +645,7 @@ Result:
|
||||
|
||||
## h3IsResClassIII
|
||||
|
||||
Returns whether [H3](#h3index) index has a resolution with Class III orientation.
|
||||
Returns whether [H3](#h3-index) index has a resolution with Class III orientation.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -678,7 +680,7 @@ Result:
|
||||
|
||||
## h3IsPentagon
|
||||
|
||||
Returns whether this [H3](#h3index) index represents a pentagonal cell.
|
||||
Returns whether this [H3](#h3-index) index represents a pentagonal cell.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -713,7 +715,7 @@ Result:
|
||||
|
||||
## h3GetFaces
|
||||
|
||||
Returns icosahedron faces intersected by a given [H3](#h3index) index.
|
||||
Returns icosahedron faces intersected by a given [H3](#h3-index) index.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -815,7 +817,7 @@ Result:
|
||||
|
||||
## h3ToCenterChild
|
||||
|
||||
Returns the center child (finer) [H3](#h3index) index contained by given [H3](#h3index) at the given resolution.
|
||||
Returns the center child (finer) [H3](#h3-index) index contained by given [H3](#h3-index) at the given resolution.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -830,7 +832,7 @@ h3ToCenterChild(index, resolution)
|
||||
|
||||
**Returned values**
|
||||
|
||||
- [H3](#h3index) index of the center child contained by given [H3](#h3index) at the given resolution. [UInt64](../../data-types/int-uint.md).
|
||||
- [H3](#h3-index) index of the center child contained by given [H3](#h3-index) at the given resolution. [UInt64](../../data-types/int-uint.md).
|
||||
|
||||
**Example**
|
||||
|
||||
|
||||
@ -5,6 +5,8 @@ sidebar_label: S2 Geometry
|
||||
|
||||
# Functions for Working with S2 Index
|
||||
|
||||
## S2Index
|
||||
|
||||
[S2](https://s2geometry.io/) is a geographical indexing system where all geographical data is represented on a three-dimensional sphere (similar to a globe).
|
||||
|
||||
In the S2 library points are represented as the S2 Index - a specific number which encodes internally a point on the surface of a unit sphere, unlike traditional (latitude, longitude) pairs. To get the S2 point index for a given point specified in the format (latitude, longitude) use the [geoToS2](#geotos2) function. Also, you can use the [s2ToGeo](#s2togeo) function for getting geographical coordinates corresponding to the specified S2 point index.
|
||||
|
||||
@ -45,13 +45,13 @@ SELECT halfMD5(array('e','x','a'), 'mple', 10, toDateTime('2019-06-15 23:00:00')
|
||||
|
||||
Calculates the MD4 from a string and returns the resulting set of bytes as FixedString(16).
|
||||
|
||||
## MD5 {#md5}
|
||||
## MD5
|
||||
|
||||
Calculates the MD5 from a string and returns the resulting set of bytes as FixedString(16).
|
||||
If you do not need MD5 in particular, but you need a decent cryptographic 128-bit hash, use the ‘sipHash128’ function instead.
|
||||
If you want to get the same result as output by the md5sum utility, use lower(hex(MD5(s))).
|
||||
|
||||
## sipHash64 {#siphash64}
|
||||
## sipHash64
|
||||
|
||||
Produces a 64-bit [SipHash](https://en.wikipedia.org/wiki/SipHash) hash value.
|
||||
|
||||
|
||||
@ -295,7 +295,7 @@ Same as `toIPv6`, but if the IPv6 address has an invalid format, it returns null
|
||||
## toIPv6
|
||||
|
||||
Converts a string form of IPv6 address to [IPv6](../data-types/ipv6.md) type. If the IPv6 address has an invalid format, returns an empty value.
|
||||
Similar to [IPv6StringToNum](#ipv6stringtonums) function, which converts IPv6 address to binary format.
|
||||
Similar to [IPv6StringToNum](#ipv6stringtonum) function, which converts IPv6 address to binary format.
|
||||
|
||||
If the input string contains a valid IPv4 address, then the IPv6 equivalent of the IPv4 address is returned.
|
||||
|
||||
|
||||
@ -5,10 +5,10 @@ sidebar_label: JSON
|
||||
---
|
||||
|
||||
There are two sets of functions to parse JSON:
|
||||
- [`simpleJSON*` (`visitParam*`)](#simplejson--visitparam-functions) which is made for parsing a limited subset of JSON extremely fast.
|
||||
- [`simpleJSON*` (`visitParam*`)](#simplejson-visitparam-functions) which is made for parsing a limited subset of JSON extremely fast.
|
||||
- [`JSONExtract*`](#jsonextract-functions) which is made for parsing ordinary JSON.
|
||||
|
||||
## simpleJSON / visitParam functions
|
||||
## simpleJSON (visitParam) functions
|
||||
|
||||
ClickHouse has special functions for working with simplified JSON. All these JSON functions are based on strong assumptions about what the JSON can be. They try to do as little as possible to get the job done as quickly as possible.
|
||||
|
||||
|
||||
@ -762,7 +762,7 @@ LIMIT 10
|
||||
|
||||
Given a size (number of bytes), this function returns a readable, rounded size with suffix (KB, MB, etc.) as string.
|
||||
|
||||
The opposite operations of this function are [parseReadableSize](#parseReadableSize), [parseReadableSizeOrZero](#parseReadableSizeOrZero), and [parseReadableSizeOrNull](#parseReadableSizeOrNull).
|
||||
The opposite operations of this function are [parseReadableSize](#parsereadablesize), [parseReadableSizeOrZero](#parsereadablesizeorzero), and [parseReadableSizeOrNull](#parsereadablesizeornull).
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -795,7 +795,7 @@ Result:
|
||||
|
||||
Given a size (number of bytes), this function returns a readable, rounded size with suffix (KiB, MiB, etc.) as string.
|
||||
|
||||
The opposite operations of this function are [parseReadableSize](#parseReadableSize), [parseReadableSizeOrZero](#parseReadableSizeOrZero), and [parseReadableSizeOrNull](#parseReadableSizeOrNull).
|
||||
The opposite operations of this function are [parseReadableSize](#parsereadablesize), [parseReadableSizeOrZero](#parsereadablesizeorzero), and [parseReadableSizeOrNull](#parsereadablesizeornull).
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -926,7 +926,7 @@ SELECT
|
||||
Given a string containing a byte size and `B`, `KiB`, `KB`, `MiB`, `MB`, etc. as a unit (i.e. [ISO/IEC 80000-13](https://en.wikipedia.org/wiki/ISO/IEC_80000) or decimal byte unit), this function returns the corresponding number of bytes.
|
||||
If the function is unable to parse the input value, it throws an exception.
|
||||
|
||||
The inverse operations of this function are [formatReadableSize](#formatReadableSize) and [formatReadableDecimalSize](#formatReadableDecimalSize).
|
||||
The inverse operations of this function are [formatReadableSize](#formatreadablesize) and [formatReadableDecimalSize](#formatreadabledecimalsize).
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -964,7 +964,7 @@ SELECT
|
||||
Given a string containing a byte size and `B`, `KiB`, `KB`, `MiB`, `MB`, etc. as a unit (i.e. [ISO/IEC 80000-13](https://en.wikipedia.org/wiki/ISO/IEC_80000) or decimal byte unit), this function returns the corresponding number of bytes.
|
||||
If the function is unable to parse the input value, it returns `NULL`.
|
||||
|
||||
The inverse operations of this function are [formatReadableSize](#formatReadableSize) and [formatReadableDecimalSize](#formatReadableDecimalSize).
|
||||
The inverse operations of this function are [formatReadableSize](#formatreadablesize) and [formatReadableDecimalSize](#formatreadabledecimalsize).
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1002,7 +1002,7 @@ SELECT
|
||||
|
||||
Given a string containing a byte size and `B`, `KiB`, `KB`, `MiB`, `MB`, etc. as a unit (i.e. [ISO/IEC 80000-13](https://en.wikipedia.org/wiki/ISO/IEC_80000) or decimal byte unit), this function returns the corresponding number of bytes. If the function is unable to parse the input value, it returns `0`.
|
||||
|
||||
The inverse operations of this function are [formatReadableSize](#formatReadableSize) and [formatReadableDecimalSize](#formatReadableDecimalSize).
|
||||
The inverse operations of this function are [formatReadableSize](#formatreadablesize) and [formatReadableDecimalSize](#formatreadabledecimalsize).
|
||||
|
||||
|
||||
**Syntax**
|
||||
@ -2711,7 +2711,7 @@ countDigits(x)
|
||||
- Number of digits. [UInt8](../data-types/int-uint.md#uint-ranges).
|
||||
|
||||
:::note
|
||||
For `Decimal` values takes into account their scales: calculates result over underlying integer type which is `(value * scale)`. For example: `countDigits(42) = 2`, `countDigits(42.000) = 5`, `countDigits(0.04200) = 4`. I.e. you may check decimal overflow for `Decimal64` with `countDecimal(x) > 18`. It's a slow variant of [isDecimalOverflow](#is-decimal-overflow).
|
||||
For `Decimal` values takes into account their scales: calculates result over underlying integer type which is `(value * scale)`. For example: `countDigits(42) = 2`, `countDigits(42.000) = 5`, `countDigits(0.04200) = 4`. I.e. you may check decimal overflow for `Decimal64` with `countDecimal(x) > 18`. It's a slow variant of [isDecimalOverflow](#isdecimaloverflow).
|
||||
:::
|
||||
|
||||
**Example**
|
||||
@ -2803,7 +2803,7 @@ currentProfiles()
|
||||
|
||||
## enabledProfiles
|
||||
|
||||
Returns settings profiles, assigned to the current user both explicitly and implicitly. Explicitly assigned profiles are the same as returned by the [currentProfiles](#current-profiles) function. Implicitly assigned profiles include parent profiles of other assigned profiles, profiles assigned via granted roles, profiles assigned via their own settings, and the main default profile (see the `default_profile` section in the main server configuration file).
|
||||
Returns settings profiles, assigned to the current user both explicitly and implicitly. Explicitly assigned profiles are the same as returned by the [currentProfiles](#currentprofiles) function. Implicitly assigned profiles include parent profiles of other assigned profiles, profiles assigned via granted roles, profiles assigned via their own settings, and the main default profile (see the `default_profile` section in the main server configuration file).
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -2916,11 +2916,11 @@ Result:
|
||||
└───────────────────────────┘
|
||||
```
|
||||
|
||||
## queryID {#queryID}
|
||||
## queryID
|
||||
|
||||
Returns the ID of the current query. Other parameters of a query can be extracted from the [system.query_log](../../operations/system-tables/query_log.md) table via `query_id`.
|
||||
|
||||
In contrast to [initialQueryID](#initial-query-id) function, `queryID` can return different results on different shards (see the example).
|
||||
In contrast to [initialQueryID](#initialqueryid) function, `queryID` can return different results on different shards (see the example).
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -2954,7 +2954,7 @@ Result:
|
||||
|
||||
Returns the ID of the initial current query. Other parameters of a query can be extracted from the [system.query_log](../../operations/system-tables/query_log.md) table via `initial_query_id`.
|
||||
|
||||
In contrast to [queryID](#query-id) function, `initialQueryID` returns the same results on different shards (see example).
|
||||
In contrast to [queryID](#queryid) function, `initialQueryID` returns the same results on different shards (see example).
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -3041,7 +3041,7 @@ shardCount()
|
||||
|
||||
**See Also**
|
||||
|
||||
- [shardNum()](#shard-num) function example also contains `shardCount()` function call.
|
||||
- [shardNum()](#shardnum) function example also contains `shardCount()` function call.
|
||||
|
||||
## getOSKernelVersion
|
||||
|
||||
|
||||
@ -200,7 +200,7 @@ Banker's rounding is a method of rounding fractional numbers
|
||||
When the rounding number is halfway between two numbers, it's rounded to the nearest even digit at the specified decimal position.
|
||||
For example: 3.5 rounds up to 4, 2.5 rounds down to 2.
|
||||
It's the default rounding method for floating point numbers defined in [IEEE 754](https://en.wikipedia.org/wiki/IEEE_754#Roundings_to_nearest).
|
||||
The [round](#rounding_functions-round) function performs the same rounding for floating point numbers.
|
||||
The [round](#round) function performs the same rounding for floating point numbers.
|
||||
The `roundBankers` function also rounds integers the same way, for example, `roundBankers(45, -1) = 40`.
|
||||
|
||||
In other cases, the function rounds numbers to the nearest integer.
|
||||
@ -274,7 +274,7 @@ roundBankers(10.755, 2) = 10.76
|
||||
|
||||
**See Also**
|
||||
|
||||
- [round](#rounding_functions-round)
|
||||
- [round](#round)
|
||||
|
||||
## roundToExp2
|
||||
|
||||
|
||||
@ -1994,7 +1994,7 @@ Result:
|
||||
|
||||
## stringJaccardIndexUTF8
|
||||
|
||||
Like [stringJaccardIndex](#stringJaccardIndex) but for UTF8-encoded strings.
|
||||
Like [stringJaccardIndex](#stringjaccardindex) but for UTF8-encoded strings.
|
||||
|
||||
## editDistance
|
||||
|
||||
|
||||
@ -262,7 +262,7 @@ Result:
|
||||
|
||||
## multiSearchAllPositionsUTF8
|
||||
|
||||
Like [multiSearchAllPositions](#multiSearchAllPositions) but assumes `haystack` and the `needle` substrings are UTF-8 encoded strings.
|
||||
Like [multiSearchAllPositions](#multisearchallpositions) but assumes `haystack` and the `needle` substrings are UTF-8 encoded strings.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -336,7 +336,7 @@ Result:
|
||||
|
||||
Like [`position`](#position) but returns the leftmost offset in a `haystack` string which matches any of multiple `needle` strings.
|
||||
|
||||
Functions [`multiSearchFirstPositionCaseInsensitive`](#multiSearchFirstPositionCaseInsensitive), [`multiSearchFirstPositionUTF8`](#multiSearchFirstPositionUTF8) and [`multiSearchFirstPositionCaseInsensitiveUTF8`](#multiSearchFirstPositionCaseInsensitiveUTF8) provide case-insensitive and/or UTF-8 variants of this function.
|
||||
Functions [`multiSearchFirstPositionCaseInsensitive`](#multisearchfirstpositioncaseinsensitive), [`multiSearchFirstPositionUTF8`](#multisearchfirstpositionutf8) and [`multiSearchFirstPositionCaseInsensitiveUTF8`](#multisearchfirstpositioncaseinsensitiveutf8) provide case-insensitive and/or UTF-8 variants of this function.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -370,7 +370,7 @@ Result:
|
||||
|
||||
## multiSearchFirstPositionCaseInsensitive
|
||||
|
||||
Like [`multiSearchFirstPosition`](#multiSearchFirstPosition) but ignores case.
|
||||
Like [`multiSearchFirstPosition`](#multisearchfirstposition) but ignores case.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -404,7 +404,7 @@ Result:
|
||||
|
||||
## multiSearchFirstPositionUTF8
|
||||
|
||||
Like [`multiSearchFirstPosition`](#multiSearchFirstPosition) but assumes `haystack` and `needle` to be UTF-8 strings.
|
||||
Like [`multiSearchFirstPosition`](#multisearchfirstposition) but assumes `haystack` and `needle` to be UTF-8 strings.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -440,7 +440,7 @@ Result:
|
||||
|
||||
## multiSearchFirstPositionCaseInsensitiveUTF8
|
||||
|
||||
Like [`multiSearchFirstPosition`](#multiSearchFirstPosition) but assumes `haystack` and `needle` to be UTF-8 strings and ignores case.
|
||||
Like [`multiSearchFirstPosition`](#multisearchfirstposition) but assumes `haystack` and `needle` to be UTF-8 strings and ignores case.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -478,7 +478,7 @@ Result:
|
||||
|
||||
Returns the index `i` (starting from 1) of the leftmost found needle<sub>i</sub> in the string `haystack` and 0 otherwise.
|
||||
|
||||
Functions [`multiSearchFirstIndexCaseInsensitive`](#multiSearchFirstIndexCaseInsensitive), [`multiSearchFirstIndexUTF8`](#multiSearchFirstIndexUTF8) and [`multiSearchFirstIndexCaseInsensitiveUTF8`](#multiSearchFirstIndexCaseInsensitiveUTF8) provide case-insensitive and/or UTF-8 variants of this function.
|
||||
Functions [`multiSearchFirstIndexCaseInsensitive`](#multisearchfirstindexcaseinsensitive), [`multiSearchFirstIndexUTF8`](#multisearchfirstindexutf8) and [`multiSearchFirstIndexCaseInsensitiveUTF8`](#multisearchfirstindexcaseinsensitiveutf8) provide case-insensitive and/or UTF-8 variants of this function.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -615,7 +615,7 @@ Result:
|
||||
|
||||
Returns 1, if at least one string needle<sub>i</sub> matches the string `haystack` and 0 otherwise.
|
||||
|
||||
Functions [`multiSearchAnyCaseInsensitive`](#multiSearchAnyCaseInsensitive), [`multiSearchAnyUTF8`](#multiSearchAnyUTF8) and []`multiSearchAnyCaseInsensitiveUTF8`](#multiSearchAnyCaseInsensitiveUTF8) provide case-insensitive and/or UTF-8 variants of this function.
|
||||
Functions [`multiSearchAnyCaseInsensitive`](#multisearchanycaseinsensitive), [`multiSearchAnyUTF8`](#multisearchanyutf8) and [`multiSearchAnyCaseInsensitiveUTF8`](#multisearchanycaseinsensitiveutf8) provide case-insensitive and/or UTF-8 variants of this function.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -719,7 +719,7 @@ Result:
|
||||
|
||||
## multiSearchAnyCaseInsensitiveUTF8
|
||||
|
||||
Like [multiSearchAnyUTF8](#multiSearchAnyUTF8) but ignores case.
|
||||
Like [multiSearchAnyUTF8](#multisearchanyutf8) but ignores case.
|
||||
|
||||
*Syntax**
|
||||
|
||||
@ -880,7 +880,7 @@ extractAll(haystack, pattern)
|
||||
|
||||
Matches all groups of the `haystack` string using the `pattern` regular expression. Returns an array of arrays, where the first array includes all fragments matching the first group, the second array - matching the second group, etc.
|
||||
|
||||
This function is slower than [extractAllGroupsVertical](#extractallgroups-vertical).
|
||||
This function is slower than [extractAllGroupsVertical](#extractallgroupsvertical).
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -952,7 +952,7 @@ Result:
|
||||
└────────────────────────────────────────────────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
## like {#like}
|
||||
## like
|
||||
|
||||
Returns whether string `haystack` matches the LIKE expression `pattern`.
|
||||
|
||||
@ -1215,7 +1215,7 @@ Result:
|
||||
|
||||
## ngramSearchCaseInsensitive
|
||||
|
||||
Provides a case-insensitive variant of [ngramSearch](#ngramSearch).
|
||||
Provides a case-insensitive variant of [ngramSearch](#ngramsearch).
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1630,7 +1630,7 @@ Result:
|
||||
|
||||
## hasSubsequenceCaseInsensitive
|
||||
|
||||
Like [hasSubsequence](#hasSubsequence) but searches case-insensitively.
|
||||
Like [hasSubsequence](#hassubsequence) but searches case-insensitively.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1665,7 +1665,7 @@ Result:
|
||||
|
||||
## hasSubsequenceUTF8
|
||||
|
||||
Like [hasSubsequence](#hasSubsequence) but assumes `haystack` and `needle` are UTF-8 encoded strings.
|
||||
Like [hasSubsequence](#hassubsequence) but assumes `haystack` and `needle` are UTF-8 encoded strings.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1700,7 +1700,7 @@ Result:
|
||||
|
||||
## hasSubsequenceCaseInsensitiveUTF8
|
||||
|
||||
Like [hasSubsequenceUTF8](#hasSubsequenceUTF8) but searches case-insensitively.
|
||||
Like [hasSubsequenceUTF8](#hassubsequenceutf8) but searches case-insensitively.
|
||||
|
||||
**Syntax**
|
||||
|
||||
|
||||
@ -10,7 +10,7 @@ sidebar_label: Type Conversion
|
||||
|
||||
ClickHouse generally uses the [same behavior as C++ programs](https://en.cppreference.com/w/cpp/language/implicit_conversion).
|
||||
|
||||
`to<type>` functions and [cast](#castx-t) behave differently in some cases, for example in case of [LowCardinality](../data-types/lowcardinality.md): [cast](#castx-t) removes [LowCardinality](../data-types/lowcardinality.md) trait `to<type>` functions don't. The same with [Nullable](../data-types/nullable.md), this behaviour is not compatible with SQL standard, and it can be changed using [cast_keep_nullable](../../operations/settings/settings.md/#cast_keep_nullable) setting.
|
||||
`to<type>` functions and [cast](#cast) behave differently in some cases, for example in case of [LowCardinality](../data-types/lowcardinality.md): [cast](#cast) removes [LowCardinality](../data-types/lowcardinality.md) trait `to<type>` functions don't. The same with [Nullable](../data-types/nullable.md), this behaviour is not compatible with SQL standard, and it can be changed using [cast_keep_nullable](../../operations/settings/settings.md/#cast_keep_nullable) setting.
|
||||
|
||||
:::note
|
||||
Be aware of potential data loss if values of a datatype are converted to a smaller datatype (for example from `Int64` to `Int32`) or between
|
||||
@ -70,7 +70,7 @@ Integer value in the `Int8`, `Int16`, `Int32`, `Int64`, `Int128` or `Int256` dat
|
||||
|
||||
Functions use [rounding towards zero](https://en.wikipedia.org/wiki/Rounding#Rounding_towards_zero), meaning they truncate fractional digits of numbers.
|
||||
|
||||
The behavior of functions for the [NaN and Inf](../data-types/float.md/#data_type-float-nan-inf) arguments is undefined. Remember about [numeric conversions issues](#numeric-conversion-issues), when using the functions.
|
||||
The behavior of functions for the [NaN and Inf](../data-types/float.md/#data_type-float-nan-inf) arguments is undefined. Remember about [numeric conversions issues](#common-issues-with-data-conversion), when using the functions.
|
||||
|
||||
**Example**
|
||||
|
||||
@ -169,7 +169,7 @@ Converts an input value to the [UInt](../data-types/int-uint.md) data type. This
|
||||
|
||||
Functions use [rounding towards zero](https://en.wikipedia.org/wiki/Rounding#Rounding_towards_zero), meaning they truncate fractional digits of numbers.
|
||||
|
||||
The behavior of functions for negative arguments and for the [NaN and Inf](../data-types/float.md/#data_type-float-nan-inf) arguments is undefined. If you pass a string with a negative number, for example `'-32'`, ClickHouse raises an exception. Remember about [numeric conversions issues](#numeric-conversion-issues), when using the functions.
|
||||
The behavior of functions for negative arguments and for the [NaN and Inf](../data-types/float.md/#data_type-float-nan-inf) arguments is undefined. If you pass a string with a negative number, for example `'-32'`, ClickHouse raises an exception. Remember about [numeric conversions issues](#common-issues-with-data-conversion), when using the functions.
|
||||
|
||||
**Example**
|
||||
|
||||
@ -996,7 +996,7 @@ Result:
|
||||
|
||||
## reinterpretAsUInt8
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt8. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt8. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1034,7 +1034,7 @@ Result:
|
||||
|
||||
## reinterpretAsUInt16
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt16. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt16. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1072,7 +1072,7 @@ Result:
|
||||
|
||||
## reinterpretAsUInt32
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt32. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt32. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1110,7 +1110,7 @@ Result:
|
||||
|
||||
## reinterpretAsUInt64
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt64. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt64. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1148,7 +1148,7 @@ Result:
|
||||
|
||||
## reinterpretAsUInt128
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt128. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt128. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1186,7 +1186,7 @@ Result:
|
||||
|
||||
## reinterpretAsUInt256
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt256. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type UInt256. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1224,7 +1224,7 @@ Result:
|
||||
|
||||
## reinterpretAsInt8
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int8. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int8. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1262,7 +1262,7 @@ Result:
|
||||
|
||||
## reinterpretAsInt16
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int16. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int16. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1300,7 +1300,7 @@ Result:
|
||||
|
||||
## reinterpretAsInt32
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int32. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int32. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1338,7 +1338,7 @@ Result:
|
||||
|
||||
## reinterpretAsInt64
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int64. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int64. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1376,7 +1376,7 @@ Result:
|
||||
|
||||
## reinterpretAsInt128
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int128. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int128. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1414,7 +1414,7 @@ Result:
|
||||
|
||||
## reinterpretAsInt256
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int256. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type Int256. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1452,7 +1452,7 @@ Result:
|
||||
|
||||
## reinterpretAsFloat32
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type Float32. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type Float32. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1486,7 +1486,7 @@ Result:
|
||||
|
||||
## reinterpretAsFloat64
|
||||
|
||||
Performs byte reinterpretation by treating the input value as a value of type Float64. Unlike [`CAST`](#castx-t), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
Performs byte reinterpretation by treating the input value as a value of type Float64. Unlike [`CAST`](#cast), the function does not attempt to preserve the original value - if the target type is not able to represent the input type, the output is meaningless.
|
||||
|
||||
**Syntax**
|
||||
|
||||
@ -1730,7 +1730,7 @@ Result:
|
||||
└─────────────────────┘
|
||||
```
|
||||
|
||||
## reinterpret(x, T)
|
||||
## reinterpret
|
||||
|
||||
Uses the same source in-memory bytes sequence for `x` value and reinterprets it to destination type.
|
||||
|
||||
@ -1766,9 +1766,9 @@ Result:
|
||||
└─────────────┴──────────────┴───────────────┘
|
||||
```
|
||||
|
||||
## CAST(x, T)
|
||||
## CAST
|
||||
|
||||
Converts an input value to the specified data type. Unlike the [reinterpret](#type_conversion_function-reinterpret) function, `CAST` tries to present the same value using the new data type. If the conversion can not be done then an exception is raised.
|
||||
Converts an input value to the specified data type. Unlike the [reinterpret](#reinterpret) function, `CAST` tries to present the same value using the new data type. If the conversion can not be done then an exception is raised.
|
||||
Several syntax variants are supported.
|
||||
|
||||
**Syntax**
|
||||
@ -1875,7 +1875,7 @@ Result:
|
||||
|
||||
Converts `x` to the `T` data type.
|
||||
|
||||
The difference from [cast(x, T)](#type_conversion_function-cast) is that `accurateCast` does not allow overflow of numeric types during cast if type value `x` does not fit the bounds of type `T`. For example, `accurateCast(-1, 'UInt8')` throws an exception.
|
||||
The difference from [cast](#cast) is that `accurateCast` does not allow overflow of numeric types during cast if type value `x` does not fit the bounds of type `T`. For example, `accurateCast(-1, 'UInt8')` throws an exception.
|
||||
|
||||
**Example**
|
||||
|
||||
@ -2061,7 +2061,7 @@ Result:
|
||||
└───────────────────────────┴──────────────────────────────┘
|
||||
```
|
||||
|
||||
## parseDateTime {#type_conversion_functions-parseDateTime}
|
||||
## parseDateTime
|
||||
|
||||
Converts a [String](../data-types/string.md) to [DateTime](../data-types/datetime.md) according to a [MySQL format string](https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-format).
|
||||
|
||||
@ -2102,15 +2102,15 @@ Alias: `TO_TIMESTAMP`.
|
||||
|
||||
## parseDateTimeOrZero
|
||||
|
||||
Same as for [parseDateTime](#type_conversion_functions-parseDateTime) except that it returns zero date when it encounters a date format that cannot be processed.
|
||||
Same as for [parseDateTime](#parsedatetime) except that it returns zero date when it encounters a date format that cannot be processed.
|
||||
|
||||
## parseDateTimeOrNull
|
||||
|
||||
Same as for [parseDateTime](#type_conversion_functions-parseDateTime) except that it returns `NULL` when it encounters a date format that cannot be processed.
|
||||
Same as for [parseDateTime](#parsedatetime) except that it returns `NULL` when it encounters a date format that cannot be processed.
|
||||
|
||||
Alias: `str_to_date`.
|
||||
|
||||
## parseDateTimeInJodaSyntax {#type_conversion_functions-parseDateTimeInJodaSyntax}
|
||||
## parseDateTimeInJodaSyntax
|
||||
|
||||
Similar to [parseDateTime](#parsedatetime), except that the format string is in [Joda](https://joda-time.sourceforge.net/apidocs/org/joda/time/format/DateTimeFormat.html) instead of MySQL syntax.
|
||||
|
||||
@ -2151,11 +2151,11 @@ SELECT parseDateTimeInJodaSyntax('2023-02-24 14:53:31', 'yyyy-MM-dd HH:mm:ss', '
|
||||
|
||||
## parseDateTimeInJodaSyntaxOrZero
|
||||
|
||||
Same as for [parseDateTimeInJodaSyntax](#type_conversion_functions-parseDateTimeInJodaSyntax) except that it returns zero date when it encounters a date format that cannot be processed.
|
||||
Same as for [parseDateTimeInJodaSyntax](#parsedatetimeinjodasyntax) except that it returns zero date when it encounters a date format that cannot be processed.
|
||||
|
||||
## parseDateTimeInJodaSyntaxOrNull
|
||||
|
||||
Same as for [parseDateTimeInJodaSyntax](#type_conversion_functions-parseDateTimeInJodaSyntax) except that it returns `NULL` when it encounters a date format that cannot be processed.
|
||||
Same as for [parseDateTimeInJodaSyntax](#parsedatetimeinjodasyntax) except that it returns `NULL` when it encounters a date format that cannot be processed.
|
||||
|
||||
## parseDateTimeBestEffort
|
||||
## parseDateTime32BestEffort
|
||||
@ -2313,11 +2313,11 @@ Same as for [parseDateTimeBestEffort](#parsedatetimebesteffort) except that it r
|
||||
|
||||
## parseDateTimeBestEffortUSOrNull
|
||||
|
||||
Same as [parseDateTimeBestEffortUS](#parsedatetimebesteffortUS) function except that it returns `NULL` when it encounters a date format that cannot be processed.
|
||||
Same as [parseDateTimeBestEffortUS](#parsedatetimebesteffortus) function except that it returns `NULL` when it encounters a date format that cannot be processed.
|
||||
|
||||
## parseDateTimeBestEffortUSOrZero
|
||||
|
||||
Same as [parseDateTimeBestEffortUS](#parsedatetimebesteffortUS) function except that it returns zero date (`1970-01-01`) or zero date with time (`1970-01-01 00:00:00`) when it encounters a date format that cannot be processed.
|
||||
Same as [parseDateTimeBestEffortUS](#parsedatetimebesteffortus) function except that it returns zero date (`1970-01-01`) or zero date with time (`1970-01-01 00:00:00`) when it encounters a date format that cannot be processed.
|
||||
|
||||
## parseDateTime64BestEffort
|
||||
|
||||
@ -2389,7 +2389,7 @@ Same as for [parseDateTime64BestEffort](#parsedatetime64besteffort), except that
|
||||
|
||||
Converts input parameter to the [LowCardinality](../data-types/lowcardinality.md) version of same data type.
|
||||
|
||||
To convert data from the `LowCardinality` data type use the [CAST](#type_conversion_function-cast) function. For example, `CAST(x as String)`.
|
||||
To convert data from the `LowCardinality` data type use the [CAST](#cast) function. For example, `CAST(x as String)`.
|
||||
|
||||
**Syntax**
|
||||
|
||||
|
||||
@ -150,7 +150,7 @@ The function also works for [Arrays](array-functions.md#function-empty) and [Str
|
||||
|
||||
**Example**
|
||||
|
||||
To generate the UUID value, ClickHouse provides the [generateUUIDv4](#uuid-function-generate) function.
|
||||
To generate the UUID value, ClickHouse provides the [generateUUIDv4](#generateuuidv4) function.
|
||||
|
||||
Query:
|
||||
|
||||
@ -190,7 +190,7 @@ The function also works for [Arrays](array-functions.md#function-notempty) or [S
|
||||
|
||||
**Example**
|
||||
|
||||
To generate the UUID value, ClickHouse provides the [generateUUIDv4](#uuid-function-generate) function.
|
||||
To generate the UUID value, ClickHouse provides the [generateUUIDv4](#generateuuidv4) function.
|
||||
|
||||
Query:
|
||||
|
||||
|
||||
@ -235,7 +235,7 @@ If `some_predicate` is not selective enough, it will return a large amount of da
|
||||
|
||||
### Distributed Subqueries and max_parallel_replicas
|
||||
|
||||
When [max_parallel_replicas](#settings-max_parallel_replicas) is greater than 1, distributed queries are further transformed.
|
||||
When [max_parallel_replicas](#distributed-subqueries-and-max_parallel_replicas) is greater than 1, distributed queries are further transformed.
|
||||
|
||||
For example, the following:
|
||||
|
||||
@ -255,7 +255,7 @@ where `M` is between `1` and `3` depending on which replica the local query is e
|
||||
|
||||
These settings affect every MergeTree-family table in the query and have the same effect as applying `SAMPLE 1/3 OFFSET (M-1)/3` on each table.
|
||||
|
||||
Therefore adding the [max_parallel_replicas](#settings-max_parallel_replicas) setting will only produce correct results if both tables have the same replication scheme and are sampled by UserID or a subkey of it. In particular, if `local_table_2` does not have a sampling key, incorrect results will be produced. The same rule applies to `JOIN`.
|
||||
Therefore adding the [max_parallel_replicas](#distributed-subqueries-and-max_parallel_replicas) setting will only produce correct results if both tables have the same replication scheme and are sampled by UserID or a subkey of it. In particular, if `local_table_2` does not have a sampling key, incorrect results will be produced. The same rule applies to `JOIN`.
|
||||
|
||||
One workaround if `local_table_2` does not meet the requirements, is to use `GLOBAL IN` or `GLOBAL JOIN`.
|
||||
|
||||
|
||||
@ -108,7 +108,7 @@ ALTER TABLE visits RENAME COLUMN webBrowser TO browser
|
||||
CLEAR COLUMN [IF EXISTS] name IN PARTITION partition_name
|
||||
```
|
||||
|
||||
Resets all data in a column for a specified partition. Read more about setting the partition name in the section [How to set the partition expression](partition.md/#how-to-set-partition-expression).
|
||||
Resets all data in a column for a specified partition. Read more about setting the partition name in the section [How to set the partition expression](../alter/partition.md/#how-to-set-partition-expression).
|
||||
|
||||
If the `IF EXISTS` clause is specified, the query won’t return an error if the column does not exist.
|
||||
|
||||
@ -173,7 +173,7 @@ ALTER TABLE visits MODIFY COLUMN browser Array(String)
|
||||
|
||||
Changing the column type is the only complex action – it changes the contents of files with data. For large tables, this may take a long time.
|
||||
|
||||
The query also can change the order of the columns using `FIRST | AFTER` clause, see [ADD COLUMN](#alter_add-column) description, but column type is mandatory in this case.
|
||||
The query also can change the order of the columns using `FIRST | AFTER` clause, see [ADD COLUMN](#add-column) description, but column type is mandatory in this case.
|
||||
|
||||
Example:
|
||||
|
||||
|
||||
@ -31,7 +31,7 @@ The following operations with [partitions](/docs/en/engines/table-engines/merget
|
||||
ALTER TABLE table_name [ON CLUSTER cluster] DETACH PARTITION|PART partition_expr
|
||||
```
|
||||
|
||||
Moves all data for the specified partition to the `detached` directory. The server forgets about the detached data partition as if it does not exist. The server will not know about this data until you make the [ATTACH](#alter_attach-partition) query.
|
||||
Moves all data for the specified partition to the `detached` directory. The server forgets about the detached data partition as if it does not exist. The server will not know about this data until you make the [ATTACH](#attach-partitionpart) query.
|
||||
|
||||
Example:
|
||||
|
||||
@ -252,7 +252,7 @@ Downloads a partition from another server. This query only works for the replica
|
||||
The query does the following:
|
||||
|
||||
1. Downloads the partition|part from the specified shard. In ‘path-in-zookeeper’ you must specify a path to the shard in ZooKeeper.
|
||||
2. Then the query puts the downloaded data to the `detached` directory of the `table_name` table. Use the [ATTACH PARTITION\|PART](#alter_attach-partition) query to add the data to the table.
|
||||
2. Then the query puts the downloaded data to the `detached` directory of the `table_name` table. Use the [ATTACH PARTITION\|PART](#attach-partitionpart) query to add the data to the table.
|
||||
|
||||
For example:
|
||||
|
||||
@ -353,7 +353,7 @@ You can specify the partition expression in `ALTER ... PARTITION` queries in dif
|
||||
- Using the keyword `ALL`. It can be used only with DROP/DETACH/ATTACH. For example, `ALTER TABLE visits ATTACH PARTITION ALL`.
|
||||
- As a tuple of expressions or constants that matches (in types) the table partitioning keys tuple. In the case of a single element partitioning key, the expression should be wrapped in the `tuple (...)` function. For example, `ALTER TABLE visits DETACH PARTITION tuple(toYYYYMM(toDate('2019-01-25')))`.
|
||||
- Using the partition ID. Partition ID is a string identifier of the partition (human-readable, if possible) that is used as the names of partitions in the file system and in ZooKeeper. The partition ID must be specified in the `PARTITION ID` clause, in a single quotes. For example, `ALTER TABLE visits DETACH PARTITION ID '201901'`.
|
||||
- In the [ALTER ATTACH PART](#alter_attach-partition) and [DROP DETACHED PART](#alter_drop-detached) query, to specify the name of a part, use string literal with a value from the `name` column of the [system.detached_parts](/docs/en/operations/system-tables/detached_parts.md/#system_tables-detached_parts) table. For example, `ALTER TABLE visits ATTACH PART '201901_1_1_0'`.
|
||||
- In the [ALTER ATTACH PART](#attach-partitionpart) and [DROP DETACHED PART](#drop-detached-partitionpart) query, to specify the name of a part, use string literal with a value from the `name` column of the [system.detached_parts](/docs/en/operations/system-tables/detached_parts.md/#system_tables-detached_parts) table. For example, `ALTER TABLE visits ATTACH PART '201901_1_1_0'`.
|
||||
|
||||
Usage of quotes when specifying the partition depends on the type of partition expression. For example, for the `String` type, you have to specify its name in quotes (`'`). For the `Date` and `Int*` types no quotes are needed.
|
||||
|
||||
|
||||
@ -6,7 +6,7 @@ sidebar_label: VIEW
|
||||
|
||||
# CREATE VIEW
|
||||
|
||||
Creates a new view. Views can be [normal](#normal-view), [materialized](#materialized-view), [live](#live-view-experimental), and [window](#window-view-experimental) (live view and window view are experimental features).
|
||||
Creates a new view. Views can be [normal](#normal-view), [materialized](#materialized-view), [live](#live-view-deprecated), and [window](#window-view-experimental) (live view and window view are experimental features).
|
||||
|
||||
## Normal View
|
||||
|
||||
|
||||
@ -33,7 +33,7 @@ GRANT [ON CLUSTER cluster_name] role [,...] TO {user | another_role | CURRENT_US
|
||||
- `role` — ClickHouse user role.
|
||||
- `user` — ClickHouse user account.
|
||||
|
||||
The `WITH ADMIN OPTION` clause grants [ADMIN OPTION](#admin-option-privilege) privilege to `user` or `role`.
|
||||
The `WITH ADMIN OPTION` clause grants [ADMIN OPTION](#admin-option) privilege to `user` or `role`.
|
||||
The `WITH REPLACE OPTION` clause replace old roles by new role for the `user` or `role`, if is not specified it appends roles.
|
||||
|
||||
## Grant Current Grants Syntax
|
||||
@ -201,7 +201,7 @@ Hierarchy of privileges:
|
||||
- `HDFS`
|
||||
- `S3`
|
||||
- [dictGet](#dictget)
|
||||
- [displaySecretsInShowAndSelect](#display-secrets)
|
||||
- [displaySecretsInShowAndSelect](#displaysecretsinshowandselect)
|
||||
- [NAMED COLLECTION ADMIN](#named-collection-admin)
|
||||
- `CREATE NAMED COLLECTION`
|
||||
- `DROP NAMED COLLECTION`
|
||||
@ -498,7 +498,7 @@ Privilege level: `DICTIONARY`.
|
||||
- `GRANT dictGet ON mydictionary TO john`
|
||||
|
||||
|
||||
### displaySecretsInShowAndSelect {#display-secrets}
|
||||
### displaySecretsInShowAndSelect
|
||||
|
||||
Allows a user to view secrets in `SHOW` and `SELECT` queries if both
|
||||
[`display_secrets_in_show_and_select` server setting](../../operations/server-configuration-parameters/settings#display_secrets_in_show_and_select)
|
||||
|
||||
@ -27,14 +27,14 @@ The features of data sampling are listed below:
|
||||
|
||||
For the `SAMPLE` clause the following syntax is supported:
|
||||
|
||||
| SAMPLE Clause Syntax | Description |
|
||||
|----------------------|------------------------------|
|
||||
| `SAMPLE k` | Here `k` is the number from 0 to 1. The query is executed on `k` fraction of data. For example, `SAMPLE 0.1` runs the query on 10% of data. [Read more](#select-sample-k) |
|
||||
| `SAMPLE n` | Here `n` is a sufficiently large integer. The query is executed on a sample of at least `n` rows (but not significantly more than this). For example, `SAMPLE 10000000` runs the query on a minimum of 10,000,000 rows. [Read more](#select-sample-n) |
|
||||
| `SAMPLE k OFFSET m` | Here `k` and `m` are the numbers from 0 to 1. The query is executed on a sample of `k` fraction of the data. The data used for the sample is offset by `m` fraction. [Read more](#select-sample-offset) |
|
||||
| SAMPLE Clause Syntax | Description |
|
||||
|----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|
||||
| `SAMPLE k` | Here `k` is the number from 0 to 1. The query is executed on `k` fraction of data. For example, `SAMPLE 0.1` runs the query on 10% of data. [Read more](#sample-k) |
|
||||
| `SAMPLE n` | Here `n` is a sufficiently large integer. The query is executed on a sample of at least `n` rows (but not significantly more than this). For example, `SAMPLE 10000000` runs the query on a minimum of 10,000,000 rows. [Read more](#sample-n) |
|
||||
| `SAMPLE k OFFSET m` | Here `k` and `m` are the numbers from 0 to 1. The query is executed on a sample of `k` fraction of the data. The data used for the sample is offset by `m` fraction. [Read more](#sample-k-offset-m) |
|
||||
|
||||
|
||||
## SAMPLE K {#select-sample-k}
|
||||
## SAMPLE K
|
||||
|
||||
Here `k` is the number from 0 to 1 (both fractional and decimal notations are supported). For example, `SAMPLE 1/2` or `SAMPLE 0.5`.
|
||||
|
||||
@ -54,7 +54,7 @@ ORDER BY PageViews DESC LIMIT 1000
|
||||
|
||||
In this example, the query is executed on a sample from 0.1 (10%) of data. Values of aggregate functions are not corrected automatically, so to get an approximate result, the value `count()` is manually multiplied by 10.
|
||||
|
||||
## SAMPLE N {#select-sample-n}
|
||||
## SAMPLE N
|
||||
|
||||
Here `n` is a sufficiently large integer. For example, `SAMPLE 10000000`.
|
||||
|
||||
@ -90,7 +90,7 @@ FROM visits
|
||||
SAMPLE 10000000
|
||||
```
|
||||
|
||||
## SAMPLE K OFFSET M {#select-sample-offset}
|
||||
## SAMPLE K OFFSET M
|
||||
|
||||
Here `k` and `m` are numbers from 0 to 1. Examples are shown below.
|
||||
|
||||
|
||||
@ -174,7 +174,7 @@ Aborts ClickHouse process (like `kill -9 {$ pid_clickhouse-server}`)
|
||||
|
||||
## Managing Distributed Tables
|
||||
|
||||
ClickHouse can manage [distributed](../../engines/table-engines/special/distributed.md) tables. When a user inserts data into these tables, ClickHouse first creates a queue of the data that should be sent to cluster nodes, then asynchronously sends it. You can manage queue processing with the [STOP DISTRIBUTED SENDS](#query_language-system-stop-distributed-sends), [FLUSH DISTRIBUTED](#query_language-system-flush-distributed), and [START DISTRIBUTED SENDS](#query_language-system-start-distributed-sends) queries. You can also synchronously insert distributed data with the [distributed_foreground_insert](../../operations/settings/settings.md#distributed_foreground_insert) setting.
|
||||
ClickHouse can manage [distributed](../../engines/table-engines/special/distributed.md) tables. When a user inserts data into these tables, ClickHouse first creates a queue of the data that should be sent to cluster nodes, then asynchronously sends it. You can manage queue processing with the [STOP DISTRIBUTED SENDS](#stop-distributed-sends), [FLUSH DISTRIBUTED](#flush-distributed), and [START DISTRIBUTED SENDS](#start-distributed-sends) queries. You can also synchronously insert distributed data with the [distributed_foreground_insert](../../operations/settings/settings.md#distributed_foreground_insert) setting.
|
||||
|
||||
### STOP DISTRIBUTED SENDS
|
||||
|
||||
|
||||
@ -54,11 +54,11 @@ Identifiers are:
|
||||
- Cluster, database, table, partition, and column names.
|
||||
- Functions.
|
||||
- Data types.
|
||||
- [Expression aliases](#expression_aliases).
|
||||
- [Expression aliases](#expression-aliases).
|
||||
|
||||
Identifiers can be quoted or non-quoted. The latter is preferred.
|
||||
|
||||
Non-quoted identifiers must match the regex `^[a-zA-Z_][0-9a-zA-Z_]*$` and can not be equal to [keywords](#syntax-keywords). Examples: `x`, `_1`, `X_y__Z123_`.
|
||||
Non-quoted identifiers must match the regex `^[a-zA-Z_][0-9a-zA-Z_]*$` and can not be equal to [keywords](#keywords). Examples: `x`, `_1`, `X_y__Z123_`.
|
||||
|
||||
If you want to use identifiers the same as keywords or you want to use other symbols in identifiers, quote it using double quotes or backticks, for example, `"id"`, `` `id` ``.
|
||||
|
||||
|
||||
@ -18,7 +18,7 @@ file([path_to_archive ::] path [,format] [,structure] [,compression])
|
||||
|
||||
**Parameters**
|
||||
|
||||
- `path` — The relative path to the file from [user_files_path](/docs/en/operations/server-configuration-parameters/settings.md#server_configuration_parameters-user_files_path). Supports in read-only mode the following [globs](#globs_in_path): `*`, `?`, `{abc,def}` (with `'abc'` and `'def'` being strings) and `{N..M}` (with `N` and `M` being numbers).
|
||||
- `path` — The relative path to the file from [user_files_path](/docs/en/operations/server-configuration-parameters/settings.md#server_configuration_parameters-user_files_path). Supports in read-only mode the following [globs](#globs-in-path): `*`, `?`, `{abc,def}` (with `'abc'` and `'def'` being strings) and `{N..M}` (with `N` and `M` being numbers).
|
||||
- `path_to_archive` - The relative path to a zip/tar/7z archive. Supports the same globs as `path`.
|
||||
- `format` — The [format](/docs/en/interfaces/formats.md#formats) of the file.
|
||||
- `structure` — Structure of the table. Format: `'column1_name column1_type, column2_name column2_type, ...'`.
|
||||
@ -128,7 +128,7 @@ Reading data from `table.csv`, located in `archive1.zip` or/and `archive2.zip`:
|
||||
SELECT * FROM file('user_files/archives/archive{1..2}.zip :: table.csv');
|
||||
```
|
||||
|
||||
## Globs in path {#globs_in_path}
|
||||
## Globs in path
|
||||
|
||||
Paths may use globbing. Files must match the whole path pattern, not only the suffix or prefix.
|
||||
|
||||
|
||||
@ -22,7 +22,7 @@ fileCluster(cluster_name, path[, format, structure, compression_method])
|
||||
**Arguments**
|
||||
|
||||
- `cluster_name` — Name of a cluster that is used to build a set of addresses and connection parameters to remote and local servers.
|
||||
- `path` — The relative path to the file from [user_files_path](/docs/en/operations/server-configuration-parameters/settings.md#server_configuration_parameters-user_files_path). Path to file also supports [globs](#globs_in_path).
|
||||
- `path` — The relative path to the file from [user_files_path](/docs/en/operations/server-configuration-parameters/settings.md#server_configuration_parameters-user_files_path). Path to file also supports [globs](#globs-in-path).
|
||||
- `format` — [Format](../../interfaces/formats.md#formats) of the files. Type: [String](../../sql-reference/data-types/string.md).
|
||||
- `structure` — Table structure in `'UserID UInt64, Name String'` format. Determines column names and types. Type: [String](../../sql-reference/data-types/string.md).
|
||||
- `compression_method` — Compression method. Supported compression types are `gz`, `br`, `xz`, `zst`, `lz4`, and `bz2`.
|
||||
@ -74,7 +74,7 @@ SELECT * FROM fileCluster('my_cluster', 'file{1,2}.csv', 'CSV', 'i UInt32, s Str
|
||||
```
|
||||
|
||||
|
||||
## Globs in Path {#globs_in_path}
|
||||
## Globs in Path
|
||||
|
||||
All patterns supported by [File](../../sql-reference/table-functions/file.md#globs-in-path) table function are supported by FileCluster.
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user