24.4.27 The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table

The INNODB_TEMP_TABLE_INFO table provides information about user-created InnoDB temporary tables that are active in an InnoDB instance. It does not provide information about internal InnoDB temporary tables used by the optimizer. The INNODB_TEMP_TABLE_INFO table is created when first queried, exists only in memory, and is not persisted to disk.

For usage information and examples, see Section 14.16.7, “InnoDB INFORMATION_SCHEMA Temporary Table Info Table”.

The INNODB_TEMP_TABLE_INFO table has these columns:

• TABLE_ID

  The table ID of the temporary table.

• NAME

  The name of the temporary table.

• N_COLS

  The number of columns in the temporary table. The number includes three hidden columns created by InnoDB (DB_ROW_ID, DB_TRX_ID, and DB_ROLL_PTR).

• SPACE

  The ID of the temporary tablespace where the temporary table resides. In 5.7, non-compressed InnoDB temporary tables reside in a shared temporary tablespace. The data file for the shared temporary tablespace is defined by the innodb_temp_data_file_path system variable. By default, there is a single data file for the shared temporary tablespace named ibtmp1, which is located in the data directory. Compressed temporary tables reside in separate file-per-table tablespaces located in the temporary file directory defined by tmpdir. The temporary tablespace ID is a nonzero value that is dynamically generated on server restart.

• PER_TABLE_TABLESPACE

  A value of TRUE indicates that the temporary table resides in a separate file-per-table tablespace. A value of FALSE indicates that the temporary table resides in the shared temporary tablespace.

• IS_COMPRESSED

  A value of TRUE indicates that the temporary table is compressed.

Example

mysql> CREATE TEMPORARY TABLE t1 (c1 INT PRIMARY KEY) ENGINE=INNODB;

mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_TEMP_TABLE_INFO\G
*************************** 1. row ***************************
            TABLE_ID: 38
                NAME: #sql26cf_6_0
              N_COLS: 4
               SPACE: 52
PER_TABLE_TABLESPACE: FALSE
       IS_COMPRESSED: FALSE

Notes

• This table is useful primarily for expert-level monitoring.

• You must have the PROCESS privilege to query this table.

• Use the INFORMATION_SCHEMA COLUMNS table or the SHOW COLUMNS statement to view additional information about the columns of this table, including data types and default values.