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ClickHouse/docs/ja/sql-reference/statements/optimize.md
TAC 371ecb4fe6
Documentation of getting-started in Japanese (#13966) 
* Remove machine_translated

* Add 'For non-Linux operating systems and for AArch64 CPU' section

* Translate getting-started/install.md to ja

* Fix index.md anchors

* Translate index.md via GitLocalize

* Translate index.md via GitLocalize

* Translate getting-started/playground.md to ja

* Translate getting-started/index.md to ja

* Translate experiment to 試す in ja

* Translate getting-started/tutoial.md to ja

* Translate getting-started/tutoial.md to ja

* Translate getting-started/example-datasets to ja

* Fix original article path

* Fix getting-started/index.md

* Revert  ja/index.md

* Fix Input/Output to 入出力

* Fix Original argicle en

* Fix missing links md files.

`getting-started/sql-reference/statements/optimize.md` is not placed in ja directory.
Currentry, it refer to english one.

* Change link to optimize.md copied from en

* Change link to alter.md ja
2020-08-27 17:46:11 +03:00

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49 OPTIMIZE

OPTIMIZE Statement

OPTIMIZE TABLE [db.]name [ON CLUSTER cluster] [PARTITION partition | PARTITION ID 'partition_id'] [FINAL] [DEDUPLICATE]

This query tries to initialize an unscheduled merge of data parts for tables with a table engine from the MergeTree family.

The OPTMIZE query is also supported for the MaterializedView and the Buffer engines. Other table engines aren’t supported.

When OPTIMIZE is used with the ReplicatedMergeTree family of table engines, ClickHouse creates a task for merging and waits for execution on all nodes (if the replication_alter_partitions_sync setting is enabled).

  • If OPTIMIZE doesn’t perform a merge for any reason, it doesn’t notify the client. To enable notifications, use the optimize_throw_if_noop setting.
  • If you specify a PARTITION, only the specified partition is optimized. How to set partition expression.
  • If you specify FINAL, optimization is performed even when all the data is already in one part.
  • If you specify DEDUPLICATE, then completely identical rows will be deduplicated (all columns are compared), it makes sense only for the MergeTree engine.

!!! warning "Warning" OPTIMIZE can’t fix the “Too many parts” error.