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* Update of english version of descriprion of the table function `file`. * New syntax for ReplacingMergeTree. Some improvements in text. * Significantly change article about SummingMergeTree. Article is restructured, text is changed in many places of the document. New syntax for table creation is described. * Descriptions of AggregateFunction and AggregatingMergeTree are updated. Russian version. * New syntax for new syntax of CREATE TABLE * Added english docs on Aggregating, Replacing and SummingMergeTree. * CollapsingMergeTree docs. English version. * 1. Update of CollapsingMergeTree. 2. Minor changes in markup * Update aggregatefunction.md * Update aggregatefunction.md * Update aggregatefunction.md * Update aggregatingmergetree.md * GraphiteMergeTree docs update. New syntax for creation of Replicated* tables. Minor changes in *MergeTree tables creation syntax. * Markup fix * Markup and language fixes * Clarification in the CollapsingMergeTree article
150 lines
5.2 KiB
Markdown
150 lines
5.2 KiB
Markdown
<a name="table_engines-graphitemergetree"></a>
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# GraphiteMergeTree
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This engine is designed for rollup (thinning and aggregating/averaging) [Graphite](http://graphite.readthedocs.io/en/latest/index.html) data. It may be helpful to developers who want to use ClickHouse as a data store for Graphite.
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You can use any ClickHouse table engine to store the Graphite data if you don't need rollup, but if you need a rollup use `GraphiteMergeTree`. The engine reduces the volume of storage and increases the efficiency of queries from Graphite.
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The engine inherits properties from [MergeTree](mergetree.md#table_engines-mergetree).
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## Creating a Table
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```sql
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CREATE TABLE [IF NOT EXISTS] [db.]table_name [ON CLUSTER cluster]
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(
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Path String,
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Time DateTime,
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Value <Numeric_type>,
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Version <Numeric_type>
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...
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) ENGINE = GraphiteMergeTree(config_section)
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[PARTITION BY expr]
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[ORDER BY expr]
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[SAMPLE BY expr]
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[SETTINGS name=value, ...]
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```
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For a description of request parameters, see [request description](../../query_language/create.md#query_language-queries-create_table).
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A table for the Graphite date should have the following columns:
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- Column with the metric name (Graphite sensor). Data type: `String`.
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- Column with the time for measuring the metric. Data type: `DateTime`.
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- Column with the value of the metric. Data type: any numeric.
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- Column with the version of the metric with the same name and time of measurement. Data type: any numeric.
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ClickHouse saves the rows with the highest version or the last written if versions are the same. Other rows are deleted during the merge of data parts.
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The names of these columns should be set in the rollup configuration.
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**GraphiteMergeTree parameters**
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- `config_section` — Name of the section in the configuration file, where are the rules of rollup set.
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**Query clauses**
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When creating a `GraphiteMergeTree` table, the same [clauses](mergetree.md#table_engines-mergetree-configuring) are required, as when creating a `MergeTree` table.
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<details markdown="1"><summary>Deprecated Method for Creating a Table</summary>
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!!! attention
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Do not use this method in new projects and, if possible, switch the old projects to the method described above.
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```sql
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CREATE TABLE [IF NOT EXISTS] [db.]table_name [ON CLUSTER cluster]
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(
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EventDate Date,
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Path String,
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Time DateTime,
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Value <Numeric_type>,
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Version <Numeric_type>
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...
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) ENGINE [=] GraphiteMergeTree(date-column [, sampling_expression], (primary, key), index_granularity, config_section)
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```
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All of the parameters excepting `config_section` have the same meaning as in `MergeTree`.
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- `config_section` — Name of the section in the configuration file, where are the rules of rollup set.
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</details>
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## Rollup configuration
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The settings for rollup are defined by the [graphite_rollup](../server_settings/settings.md#server_settings-graphite_rollup) parameter in the server configuration. The name of the parameter could be any. You can create several configurations and use them for different tables.
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Rollup configuration structure:
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```
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required-columns
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pattern
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regexp
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function
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age + precision
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...
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pattern
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...
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default
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function
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age + precision
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...
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```
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When processing a row, ClickHouse checks the rules in the `pattern` section. If the metric name matches the `regexp`, the rules from the `pattern`section are applied; otherwise, the rules from the `default` section are used.
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The rules are defined with fields `function` and `age + precision`.
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Fields for `pattern` and `default` sections:
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- `regexp`– A pattern for the metric name.
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- `age` – The minimum age of the data in seconds.
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- `precision`– How precisely to define the age of the data in seconds.
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- `function` – The name of the aggregating function to apply to data whose age falls within the range `[age, age + precision]`.
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The `required-columns`:
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- `path_column_name` — Column with the metric name (Graphite sensor).
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- `time_column_name` — Column with the time for measuring the metric.
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- `value_column_name` — Column with the value of the metric at the time set in `time_column_name`.
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- `version_column_name` — Column with the version timestamp of the metric with the same name and time remains in the database.
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Example of settings:
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```xml
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<graphite_rollup>
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<path_column_name>Path</path_column_name>
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<time_column_name>Time</time_column_name>
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<value_column_name>Value</value_column_name>
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<version_column_name>Version</version_column_name>
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<pattern>
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<regexp>click_cost</regexp>
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<function>any</function>
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<retention>
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<age>0</age>
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<precision>5</precision>
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</retention>
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<retention>
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<age>86400</age>
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<precision>60</precision>
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</retention>
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</pattern>
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<default>
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<function>max</function>
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<retention>
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<age>0</age>
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<precision>60</precision>
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</retention>
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<retention>
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<age>3600</age>
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<precision>300</precision>
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</retention>
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<retention>
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<age>86400</age>
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<precision>3600</precision>
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</retention>
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</default>
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</graphite_rollup>
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```
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[Original article](https://clickhouse.yandex/docs/en/operations/table_engines/graphitemergetree/) <!--hide-->
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