IMPORTANT: No additional bug fixes or documentation updates
will be released for this version. For the latest information, see the
current release documentation.
Frozen Indices
editFrozen Indices
editElasticsearch frozen indices are a useful and powerful tool for hot/warm architecture introduced in Elasticsearch 6.6, essentially by trading speed for memory. Elasticsearch SQL supports frozen indices and similar to Elasticsearch, due to their performance characteristics, allows searches on them only when explicitly told so by user - in other words, by default, frozen indices are not included in searches.
One can toggle the use of frozen indices through:
- dedicated configuration parameter
-
Set to
true
propertiesindex_include_frozen
in the SQL REST API orindex.include.frozen
in the drivers to include frozen indices. - dedicated keyword
-
Explicitly perform the inclusion through the dedicated
FROZEN
keyword in theFROM
clause orINCLUDE FROZEN
in theSHOW
commands:
SHOW TABLES INCLUDE FROZEN; name | type | kind ---------------+---------------+--------------- archive |BASE TABLE |FROZEN INDEX emp |BASE TABLE |INDEX employees |VIEW |ALIAS library |BASE TABLE |INDEX
SELECT * FROM FROZEN archive LIMIT 1; author | name | page_count | release_date -----------------+--------------------+---------------+-------------------- James S.A. Corey |Leviathan Wakes |561 |2011-06-02T00:00:00Z
Unless enabled, frozen indices are completely ignored; it is as if they do not exist and as such, queries ran against them are likely to fail.