Manipulating Column Statistics
The following operations are available:
ALTER TABLE [db].table ADD STATISTIC (columns list) TYPE type
- Adds statistic description to tables metadata.ALTER TABLE [db].table DROP STATISTIC (columns list) TYPE type
- Removes statistic description from tables metadata and deletes statistic files from disk.ALTER TABLE [db].table CLEAR STATISTIC (columns list) TYPE type
- Deletes statistic files from disk.ALTER TABLE [db.]table MATERIALIZE STATISTIC (columns list) TYPE type
- Rebuilds the statistic for columns. Implemented as a mutation.
The first two commands are lightweight in a sense that they only change metadata or remove files.
Also, they are replicated, syncing statistics metadata via ZooKeeper.
Statistic manipulation is supported only for tables with *MergeTree
engine (including replicated variants).