Frozen Indices
Elasticsearch 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
properties index_include_frozen
in the SQL REST API or index.include.frozen
in the drivers to include frozen indices.
dedicated keyword
Explicitly perform the inclusion through the dedicated FROZEN
keyword in the FROM
clause or INCLUDE FROZEN
in the SHOW
commands:
SHOW TABLES INCLUDE FROZEN;
name | type | kind
---------------+----------+---------------
archive |TABLE |FROZEN INDEX
emp |TABLE |INDEX
employees |VIEW |ALIAS
library |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.