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Information Schema PARTITIONS Table

The Information Schema PARTITIONS contains information about table partitions, with each record corresponding to a single partition or subpartition of a partitioned table. Each non-partitioned table also has a record in the PARTITIONS table, but most of the values are NULL.

It contains the following columns:

Column	Description
`TABLE_CATALOG`	Always `def`.
`TABLE_SCHEMA`	Database name.
`TABLE_NAME`	Table name containing the partition.
`PARTITION_NAME`	Partition name.
`SUBPARTITION_NAME`	Subpartition name, or `NULL` if not a subpartition.
`PARTITION_ORDINAL_POSITION`	Order of the partition starting from 1.
`SUBPARTITION_ORDINAL_POSITION`	Order of the subpartition starting from 1.
`PARTITION_METHOD`	The partitioning type; one of `RANGE`, `LIST`, `HASH`, `LINEAR HASH`, `KEY` or `LINEAR KEY`.
`SUBPARTITION_METHOD`	Subpartition type; one of `HASH`, `LINEAR HASH`, `KEY` or `LINEAR KEY`, or `NULL` if not a subpartition.
`PARTITION_EXPRESSION`	Expression used to create the partition by the `CREATE TABLE` or `ALTER TABLE` statement.
`SUBPARTITION_EXPRESSION`	Expression used to create the subpartition by the `CREATE TABLE` or `ALTER TABLE` statement, or `NULL` if not a subpartition.
`PARTITION_DESCRIPTION`	For a `RANGE` partition, contains either `MAXINTEGER` or an integer, as set in the `VALUES LESS THAN` clause. For a `LIST` partition, contains a comma-separated list of integers, as set in the `VALUES IN`. `NULL` if another type of partition.
`TABLE_ROWS`	Number of rows in the table (may be an estimate for some storage engines).
`AVG_ROW_LENGTH`	Average row length, that is `DATA_LENGTH` divided by `TABLE_ROWS`
`DATA_LENGTH`	Total number of bytes stored in all rows of the partition.
`MAX_DATA_LENGTH`	Maximum bytes that could be stored in the partition.
`INDEX_LENGTH`	Size in bytes of the partition index file.
`DATA_FREE`	Unused bytes allocated to the partition.
`CREATE_TIME`	Time the partition was created
`UPDATE_TIME`	Time the partition was last modified.
`CHECK_TIME`	Time the partition was last checked, or `NULL` for storage engines that don't record this information.
`CHECKSUM`	Checksum value, or `NULL` if none.
`PARTITION_COMMENT`	Partition comment, truncated to 80 characters, or an empty string if no comment.
`NODEGROUP`	Node group, only used for MySQL Cluster, defaults to `0`.
`TABLESPACE_NAME`	Always `default`.

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https://mariadb.com/kb/en/information-schema-partitions-table/