thevar1able/ClickHouse
1
0
Fork 0
mirror of https://github.com/ClickHouse/ClickHouse.git synced 2024-11-21 15:12:02 +00:00
Code Issues Packages Projects Releases Wiki Activity

DOCAPI-7430: MergeTree INDEX bloom filter docs. (#5992)

Browse Source 
* DOCAPI-7430: MergeTree INDEX bloom filter docs.

* DOCAPI-7430: Updated bloom filter docs with the parameter description.
This commit is contained in:
BayoNet 2019-08-16 18:31:29 +03:00 committed by GitHub
parent da6925f74f
commit 4b91e02d68
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 13 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
docs/en/operations/table_engines/mergetree.md
View File

@ -45,7 +45,10 @@ CREATE TABLE [IF NOT EXISTS] [db.]table_name [ON CLUSTER cluster]
[SETTINGS name=value, ...]
```
For descriptions of request parameters, see the [request description](../../query_language/create.md).
For a description of parameters, see the [CREATE query description](../../query_language/create.md).
!!! note "Note"
`INDEX` is an experimental feature, see [Data Skipping Indexes](#table_engine-mergetree-data_skipping-indexes).
### Query Clauses
@ -236,7 +239,7 @@ ClickHouse cannot use an index if the values of the primary key in the query par
ClickHouse uses this logic not only for days of the month sequences, but for any primary key that represents a partially-monotonic sequence.
### Data Skipping Indices (Experimental)
### Data Skipping Indexes (Experimental) {#table_engine-mergetree-data_skipping-indexes}
You need to set `allow_experimental_data_skipping_indices` to 1 to use indices. (run `SET allow_experimental_data_skipping_indices = 1`).
@ -295,6 +298,14 @@ SELECT count() FROM table WHERE u64 * i32 == 10 AND u64 * length(s) >= 1234
The same as `ngrambf_v1`, but stores tokens instead of ngrams. Tokens are sequences separated by non-alphanumeric characters.
- `bloom_filter([false_positive])` — Stores [bloom filter](https://en.wikipedia.org/wiki/Bloom_filter) for the specified columns.
The `false_positive` optional parameter is the probability of false positive response from the filter. Possible values: (0, 1). Default value: 0.025.
Supported data types: `Int*`, `UInt*`, `Float*`, `Enum`, `Date`, `DateTime`, `String`, `FixedString`.
Supported for the following functions: [equals](../../query_language/functions/comparison_functions.md), [notEquals](../../query_language/functions/comparison_functions.md), [in](../../query_language/functions/in_functions.md), [notIn](../../query_language/functions/in_functions.md).
```sql
INDEX sample_index (u64 * length(s)) TYPE minmax GRANULARITY 4
INDEX sample_index2 (u64 * length(str), i32 + f64 * 100, date, str) TYPE set(100) GRANULARITY 4