The REINDEX command is used to delete and recreate indexes from scratch. This is useful when the definition of a collation sequence has changed, or when there are indexes on expressions involving a function whose definition has changed.
If the REINDEX keyword is not followed by a collation-sequence or database object identifier or the keyword "EXPRESSIONS", then all indexes in all attached databases are rebuilt.
If the REINDEX keyword is followed by a collation-sequence name, then all indexes in all attached databases that use the named collation sequences are recreated.
Or, if the argument attached to the REINDEX identifies a specific database table, then all indexes attached to the database table are rebuilt. If it identifies a specific database index, then just that index is recreated.
If the argument is "EXPRESSIONS", then all indexes on expressions are rebuilt. The ability to rebuild expression indexes in a single command like this is new as of SQLite version 3.53.0 (2026-04-09).
For a command of the form "REINDEX name", a match against collation-name takes precedence over a match against index-name or table-name. This ambiguity in the syntax may be avoided by always specifying a schema-name when reindexing a specific table or index. If name is EXPRESSIONS, then in addition to rebuilding all expression indexes, the command also rebuilds any indexes that use a collating sequence named "expressions" or the indexes of a table named "expressions" or an index named "expressions", following the precedence rules above.
This page was last updated on 2026-03-21 13:08:51Z