mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-09-24 10:40:49 +00:00
23 lines
1.1 KiB
Markdown
23 lines
1.1 KiB
Markdown
---
|
|
toc_hidden_folder: true
|
|
toc_priority: 42
|
|
toc_title: INDEX
|
|
---
|
|
|
|
# Manipulating Data Skipping Indices {#manipulations-with-data-skipping-indices}
|
|
|
|
The following operations are available:
|
|
|
|
- `ALTER TABLE [db].name ADD INDEX name expression TYPE type GRANULARITY value AFTER name [AFTER name2]` - Adds index description to tables metadata.
|
|
|
|
- `ALTER TABLE [db].name DROP INDEX name` - Removes index description from tables metadata and deletes index files from disk.
|
|
|
|
- `ALTER TABLE [db.]table MATERIALIZE INDEX name IN PARTITION partition_name` - The query rebuilds the secondary index `name` in the partition `partition_name`. Implemented as a [mutation](../../../../sql-reference/statements/alter/index.md#mutations).
|
|
|
|
The first two commands are lightweight in a sense that they only change metadata or remove files.
|
|
|
|
Also, they are replicated, syncing indices metadata via ZooKeeper.
|
|
|
|
!!! note "Note"
|
|
Index manipulation is supported only for tables with [`*MergeTree`](../../../../engines/table-engines/mergetree-family/mergetree.md) engine (including [replicated](../../../../engines/table-engines/mergetree-family/replication.md) variants).
|