The INFORMATION_SCHEMA PARTITIONS Table • PARTITION_DESCRIPTION • TABLE_ROWS • AVG_ROW_LENGTH • DATA_LENGTH • MAX_DATA_LENGTH 4806 The maximum number of bytes that can be stored in this partition or subpartition. For  NDB  tables, you can also obtain this information using the  ndb_desc  utility. The total length of all rows stored in this partition or subpartition, in bytes; that is, the total number of bytes stored in the partition or subpartition. For  NDB  tables, you can also obtain this information using the  ndb_desc  utility. The average length of the rows stored in this partition or subpartition, in bytes. This is the same as DATA_LENGTH  divided by  TABLE_ROWS . For  NDB  tables, you can also obtain this information using the  ndb_desc  utility. For partitioned  InnoDB  tables, the row count given in the  TABLE_ROWS  column is only an estimated value used in SQL optimization, and may not always be exact. The number of table rows in the partition. For partitions whose  PARTITION_METHOD  is other than  RANGE  or  LIST , this column is always  NULL . This column is used for RANGE and LIST partitions. For a  RANGE  partition, it contains the value set in the partition’s  VALUES LESS THAN  clause, which can be either an integer or  MAXVALUE . For a  LIST partition, this column contains the values defined in the partition’s  VALUES IN  clause, which is a list of comma-separated integer values. This works in the same fashion for the subpartitioning expression that defines the subpartitioning for a table as  PARTITION_EXPRESSION  does for the partitioning expression used to define a table’s partitioning. If the table has no subpartitions, this column is  NULL . • SUBPARTITION_EXPRESSION The  PARTITION_EXPRESSION  column in a  PARTITIONS  table row for a partition from this table displays  c1 + c2 , as shown here: c3 VARCHAR(25) ) PARTITION BY HASH(c1 + c2) PARTITIONS 4; mysql>  SELECT DISTINCT PARTITION_EXPRESSION FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_NAME=’tp’ AND TABLE_SCHEMA=’test’; +----------------------+ | PARTITION_EXPRESSION | +----------------------+ | c1 + c2 | +----------------------+