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
namein the partition
partition_name. Implemented as a mutation.
The first two commands areare lightweight in a sense that they only change metadata or remove files.
Also, they are replicated, syncing indices metadata via ZooKeeper.
Index manipulation is supported only for tables with
*MergeTree engine (including