Manipulating 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.

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

Index manipulation is supported only for tables with *MergeTree engine (including replicated variants).