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If theinnodb_read_only system variable is enabled,ANALYZE TABLE may fail because it cannot update statistics tables in the data dictionary, which useInnoDB. ForANALYZE TABLE operations that update the key distribution, failure may occur even if the operation updates the table itself (for example, if it is aMyISAM table). To obtain the updated distribution statistics, setinformation_schema_stats_expiry=0.

• TABLE_CATALOG

  The name of the catalog to which the table belongs. This value is alwaysdef.

• TABLE_SCHEMA

  The name of the schema (database) to which the table belongs.

• TABLE_NAME

  The name of the table.

• TABLE_TYPE

  BASE TABLE for a table,VIEW for a view, orSYSTEM VIEW for anINFORMATION_SCHEMA table.

  TheTABLES table does not listTEMPORARY tables.

• ENGINE

  The storage engine for the table. SeeChapter 17,The InnoDB Storage Engine, andChapter 18,Alternative Storage Engines.

  For partitioned tables,ENGINE shows the name of the storage engine used by all partitions.

• VERSION

  This column is unused. With the removal of.frm files in MySQL 8.0, this column now reports a hardcoded value of10, which is the last.frm file version used in MySQL 5.7.

• ROW_FORMAT

  The row-storage format (Fixed,Dynamic,Compressed,Redundant,Compact). ForMyISAM tables,Dynamic corresponds to whatmyisamchk -dvv reports asPacked.

• TABLE_ROWS

  The number of rows. Some storage engines, such asMyISAM, store the exact count. For other storage engines, such asInnoDB, this value is an approximation, and may vary from the actual value by as much as 40% to 50%. In such cases, useSELECT COUNT(*) to obtain an accurate count.

  TABLE_ROWS isNULL forINFORMATION_SCHEMA tables.

  ForInnoDB tables, the row count is only a rough estimate used in SQL optimization. (This is also true if theInnoDB table is partitioned.)

• AVG_ROW_LENGTH

  The average row length.

• DATA_LENGTH

  ForMyISAM,DATA_LENGTH is the length of the data file, in bytes.

  ForInnoDB,DATA_LENGTH is the approximate amount of space allocated for the clustered index, in bytes. Specifically, it is the clustered index size, in pages, multiplied by theInnoDB page size.

  Refer to the notes at the end of this section for information regarding other storage engines.

• MAX_DATA_LENGTH

  ForMyISAM,MAX_DATA_LENGTH is maximum length of the data file. This is the total number of bytes of data that can be stored in the table, given the data pointer size used.

  Unused forInnoDB.

  Refer to the notes at the end of this section for information regarding other storage engines.

• INDEX_LENGTH

  ForMyISAM,INDEX_LENGTH is the length of the index file, in bytes.

  ForInnoDB,INDEX_LENGTH is the approximate amount of space allocated for non-clustered indexes, in bytes. Specifically, it is the sum of non-clustered index sizes, in pages, multiplied by theInnoDB page size.

  Refer to the notes at the end of this section for information regarding other storage engines.

• DATA_FREE

  The number of allocated but unused bytes.

  InnoDB tables report the free space of the tablespace to which the table belongs. For a table located in the shared tablespace, this is the free space of the shared tablespace. If you are using multiple tablespaces and the table has its own tablespace, the free space is for only that table. Free space means the number of bytes in completely free extents minus a safety margin. Even if free space displays as 0, it may be possible to insert rows as long as new extents need not be allocated.

  For NDB Cluster,DATA_FREE shows the space allocated on disk for, but not used by, a Disk Data table or fragment on disk. (In-memory data resource usage is reported by theDATA_LENGTH column.)

  For partitioned tables, this value is only an estimate and may not be absolutely correct. A more accurate method of obtaining this information in such cases is to query theINFORMATION_SCHEMAPARTITIONS table, as shown in this example:

  SELECT SUM(DATA_FREE)    FROM  INFORMATION_SCHEMA.PARTITIONS    WHERE TABLE_SCHEMA = 'mydb'    AND   TABLE_NAME   = 'mytable';

  For more information, seeSection 28.3.26, “The INFORMATION_SCHEMA PARTITIONS Table”.

• AUTO_INCREMENT

  The nextAUTO_INCREMENT value.

• CREATE_TIME

  When the table was created.

• UPDATE_TIME

  When the table was last updated. For some storage engines, this value isNULL. Even withfile-per-table mode with eachInnoDB table in a separate.ibd file,change buffering can delay the write to the data file, so the file modification time is different from the time of the last insert, update, or delete. ForMyISAM, the data file timestamp is used; however, on Windows the timestamp is not updated by updates, so the value is inaccurate.

  UPDATE_TIME displays a timestamp value for the lastUPDATE,INSERT, orDELETE performed onInnoDB tables that are not partitioned. For MVCC, the timestamp value reflects theCOMMIT time, which is considered the last update time. Timestamps are not persisted when the server is restarted or when the table is evicted from theInnoDB data dictionary cache.

• CHECK_TIME

  When the table was last checked. Not all storage engines update this time, in which case, the value is alwaysNULL.

  For partitionedInnoDB tables,CHECK_TIME is alwaysNULL.

• TABLE_COLLATION

  The table default collation. The output does not explicitly list the table default character set, but the collation name begins with the character set name.

• CHECKSUM

  The live checksum value, if any.

• CREATE_OPTIONS

  Extra options used withCREATE TABLE.

  CREATE_OPTIONS showspartitioned for a partitioned table.

  CREATE_OPTIONS shows theENCRYPTION clause specified for tables created in file-per-table tablespaces. It shows the encryption clause for file-per-table tablespaces if the table is encrypted or if the specified encryption differs from the schema encryption. The encryption clause is not shown for tables created in general tablespaces. To identify encrypted file-per-table and general tablespaces, query theINNODB_TABLESPACESENCRYPTION column.

  When creating a table withstrict mode disabled, the storage engine's default row format is used if the specified row format is not supported. The actual row format of the table is reported in theROW_FORMAT column.CREATE_OPTIONS shows the row format that was specified in theCREATE TABLE statement.

  When altering the storage engine of a table, table options that are not applicable to the new storage engine are retained in the table definition to enable reverting the table with its previously defined options to the original storage engine, if necessary. TheCREATE_OPTIONS column may show retained options.

• TABLE_COMMENT

  The comment used when creating the table (or information as to why MySQL could not access the table information).

• ForNDB tables, the output of this statement shows appropriate values for theAVG_ROW_LENGTH andDATA_LENGTH columns, with the exception thatBLOB columns are not taken into account.

• ForNDB tables,DATA_LENGTH includes data stored in main memory only; theMAX_DATA_LENGTH andDATA_FREE columns apply to Disk Data.

• For NDB Cluster Disk Data tables,MAX_DATA_LENGTH shows the space allocated for the disk part of a Disk Data table or fragment. (In-memory data resource usage is reported by theDATA_LENGTH column.)

• ForMEMORY tables, theDATA_LENGTH,MAX_DATA_LENGTH, andINDEX_LENGTH values approximate the actual amount of allocated memory. The allocation algorithm reserves memory in large amounts to reduce the number of allocation operations.

• For views, mostTABLES columns are 0 orNULL except thatTABLE_NAME indicates the view name,CREATE_TIME indicates the creation time, andTABLE_COMMENT saysVIEW.