The Ultimate Guide to High Availability with MariaDB

Information Schema QUERY_CACHE_INFO Table

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Description

The table is not a standard Information Schema table, and is a MariaDB extension.

The QUERY_CACHE_INFO table is created by the QUERY_CACHE_INFO plugin, and allows you to see the contents of the query cache. It creates a table in the information_schema database that shows all queries that are in the cache. You must have the PROCESS privilege (see GRANT) to use this table.

It contains the following columns:

ColumnDescription
STATEMENT_SCHEMADatabase used when query was included
STATEMENT_TEXTQuery text
RESULT_BLOCKS_COUNTNumber of result blocks
RESULT_BLOCKS_SIZESize in bytes of result blocks
RESULT_BLOCKS_SIZE_USEDSize in bytes of used blocks

For example:

SELECT * FROM information_schema.QUERY_CACHE_INFO;
+------------------+-----------------+---------------------+--------------------+-------------------------+
| STATEMENT_SCHEMA | STATEMENT_TEXT  | RESULT_BLOCKS_COUNT | RESULT_BLOCKS_SIZE | RESULT_BLOCKS_SIZE_USED |
+------------------+-----------------+---------------------+--------------------+-------------------------+
...
| test             | SELECT * FROM a |                   1 |                512 |                     143 |
| test             | select * FROM a |                   1 |                512 |                     143 |
...
+------------------+-----------------+---------------------+--------------------+-------------------------

The QUERY_CACHE_INFO table will be removed in a future release, and replaced by the QUERY_CACHE_QUERIES table (see MDEV-4682).

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