Chapter 20. INFORMATION_SCHEMA Tables

Table of Contents

20.1. The INFORMATION_SCHEMA SCHEMATA Table
20.2. The INFORMATION_SCHEMA TABLES Table
20.3. The INFORMATION_SCHEMA COLUMNS Table
20.4. The INFORMATION_SCHEMA STATISTICS Table
20.5. The INFORMATION_SCHEMA USER_PRIVILEGES Table
20.6. The INFORMATION_SCHEMA SCHEMA_PRIVILEGES Table
20.7. The INFORMATION_SCHEMA TABLE_PRIVILEGES Table
20.8. The INFORMATION_SCHEMA COLUMN_PRIVILEGES Table
20.9. The INFORMATION_SCHEMA CHARACTER_SETS Table
20.10. The INFORMATION_SCHEMA COLLATIONS Table
20.11. The INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY Table
20.12. The INFORMATION_SCHEMA TABLE_CONSTRAINTS Table
20.13. The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table
20.14. The INFORMATION_SCHEMA ROUTINES Table
20.15. The INFORMATION_SCHEMA VIEWS Table
20.16. The INFORMATION_SCHEMA TRIGGERS Table
20.17. The INFORMATION_SCHEMA PLUGINS Table
20.18. The INFORMATION_SCHEMA ENGINES Table
20.19. The INFORMATION_SCHEMA PARTITIONS Table
20.20. The INFORMATION_SCHEMA EVENTS Table
20.21. The INFORMATION_SCHEMA FILES Table
20.22. The INFORMATION_SCHEMA TABLESPACES Table
20.23. The INFORMATION_SCHEMA PROCESSLIST Table
20.24. The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table
20.25. The INFORMATION_SCHEMA GLOBAL_STATUS and SESSION_STATUS Tables
20.26. The INFORMATION_SCHEMA GLOBAL_VARIABLES and SESSION_VARIABLES Tables
20.27. The INFORMATION_SCHEMA PARAMETERS Table
20.28. The INFORMATION_SCHEMA PROFILING Table
20.29. INFORMATION_SCHEMA Tables for InnoDB
20.29.1. The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables
20.29.2. The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables
20.29.3. The INFORMATION_SCHEMA INNODB_TRX Table
20.29.4. The INFORMATION_SCHEMA INNODB_LOCKS Table
20.29.5. The INFORMATION_SCHEMA INNODB_LOCK_WAITS Table
20.30. Other INFORMATION_SCHEMA Tables
20.31. Extensions to SHOW Statements

INFORMATION_SCHEMA provides access to database metadata.

Metadata is data about the data, such as the name of a database or table, the data type of a column, or access privileges. Other terms that sometimes are used for this information are data dictionary and system catalog.

INFORMATION_SCHEMA is the information database, the place that stores information about all the other databases that the MySQL server maintains. Inside INFORMATION_SCHEMA there are several read-only tables. They are actually views, not base tables, so there are no files associated with them.

In effect, we have a database named INFORMATION_SCHEMA, although the server does not create a database directory with that name. It is possible to select INFORMATION_SCHEMA as the default database with a USE statement, but it is possible only to read the contents of tables. You cannot insert into them, update them, or delete from them.

Here is an example of a statement that retrieves information from INFORMATION_SCHEMA:

mysql> SELECT table_name, table_type, engine
    -> FROM information_schema.tables
    -> WHERE table_schema = 'db5'
    -> ORDER BY table_name DESC;
+------------+------------+--------+
| table_name | table_type | engine |
+------------+------------+--------+
| v56        | VIEW       | NULL   |
| v3         | VIEW       | NULL   |
| v2         | VIEW       | NULL   |
| v          | VIEW       | NULL   |
| tables     | BASE TABLE | MyISAM |
| t7         | BASE TABLE | MyISAM |
| t3         | BASE TABLE | MyISAM |
| t2         | BASE TABLE | MyISAM |
| t          | BASE TABLE | MyISAM |
| pk         | BASE TABLE | InnoDB |
| loop       | BASE TABLE | MyISAM |
| kurs       | BASE TABLE | MyISAM |
| k          | BASE TABLE | MyISAM |
| into       | BASE TABLE | MyISAM |
| goto       | BASE TABLE | MyISAM |
| fk2        | BASE TABLE | InnoDB |
| fk         | BASE TABLE | InnoDB |
+------------+------------+--------+
17 rows in set (0.01 sec)

Explanation: The statement requests a list of all the tables in database db5, in reverse alphabetic order, showing just three pieces of information: the name of the table, its type, and its storage engine.

The definition for character columns (for example, TABLES.TABLE_NAME) is generally VARCHAR(N) CHARACTER SET utf8 where N is at least 64. MySQL uses the default collation for this character set (utf8_general_ci) for all searches, sorts, comparisons, and other string operations on such columns. However, searches in INFORMATION_SCHEMA string columns are also affected by file system case sensitivity. For more information, see Section 9.1.7.9, “Collation and INFORMATION_SCHEMA Searches”.

Each MySQL user has the right to access these tables, but can see only the rows in the tables that correspond to objects for which the user has the proper access privileges. In some cases (for example, the ROUTINE_DEFINITION column in the INFORMATION_SCHEMA.ROUTINES table), users who have insufficient privileges will see NULL.

The SELECT ... FROM INFORMATION_SCHEMA statement is intended as a more consistent way to provide access to the information provided by the various SHOW statements that MySQL supports (SHOW DATABASES, SHOW TABLES, and so forth). Using SELECT has these advantages, compared to SHOW:

However, because SHOW is popular and because it might be confusing were it to disappear, the advantages of conventional syntax are not a sufficient reason to eliminate SHOW. In fact, along with the implementation of INFORMATION_SCHEMA, there are enhancements to SHOW as well. These are described in Section 20.31, “Extensions to SHOW Statements”.

There is no difference between the privileges required for SHOW statements and those required to select information from INFORMATION_SCHEMA. In either case, you have to have some privilege on an object in order to see information about it.

INFORMATION_SCHEMA queries that search for information from more than one database might take a long time and impact performance. To check the efficiency of a query, you can use EXPLAIN. For information about EXPLAIN output that is specific to interpreting the cost of INFORMATION_SCHEMA queries, see Section 7.2.4, “Optimizing INFORMATION_SCHEMA Queries”.

The implementation for the INFORMATION_SCHEMA table structures in MySQL follows the ANSI/ISO SQL:2003 standard Part 11 Schemata. Our intent is approximate compliance with SQL:2003 core feature F021 Basic information schema.

Users of SQL Server 2000 (which also follows the standard) may notice a strong similarity. However, MySQL has omitted many columns that are not relevant for our implementation, and added columns that are MySQL-specific. One such column is the ENGINE column in the INFORMATION_SCHEMA.TABLES table.

Although other DBMSs use a variety of names, like syscat or system, the standard name is INFORMATION_SCHEMA.

The following sections describe each of the tables and columns that are in INFORMATION_SCHEMA. For each column, there are three pieces of information:

To avoid using any name that is reserved in the standard or in DB2, SQL Server, or Oracle, we changed the names of some columns marked “MySQL extension”. (For example, we changed COLLATION to TABLE_COLLATION in the TABLES table.) See the list of reserved words near the end of this article: http://web.archive.org/web/20070409075643rn_1/www.dbazine.com/db2/db2-disarticles/gulutzan5.

Each section indicates what SHOW statement is equivalent to a SELECT that retrieves information from INFORMATION_SCHEMA, if there is such a statement. For SHOW statements that display information for the default database if you omit a FROM db_name clause, you can often select information for the default database by adding an AND TABLE_SCHEMA = SCHEMA() condition to the WHERE clause of a query that retrieves information from an INFORMATION_SCHEMA table.

Note

At present, there are some missing columns and some columns out of order. We are working on this and updating the documentation as changes are made.

For answers to questions that are often asked concerning the INFORMATION_SCHEMA database, see Section B.7, “MySQL 5.5 FAQ: INFORMATION_SCHEMA.

20.1. The INFORMATION_SCHEMA SCHEMATA Table

A schema is a database, so the SCHEMATA table provides information about databases.

INFORMATION_SCHEMA NameSHOW NameRemarks
CATALOG_NAME def
SCHEMA_NAME Database
DEFAULT_CHARACTER_SET_NAME  
DEFAULT_COLLATION_NAME  
SQL_PATH NULL

The following statements are equivalent:

SELECT SCHEMA_NAME AS `Database`
  FROM INFORMATION_SCHEMA.SCHEMATA
  [WHERE SCHEMA_NAME LIKE 'wild']

SHOW DATABASES
  [LIKE 'wild']

20.2. The INFORMATION_SCHEMA TABLES Table

The TABLES table provides information about tables in databases.

INFORMATION_SCHEMA NameSHOW NameRemarks
TABLE_CATALOG def
TABLE_SCHEMATable_... 
TABLE_NAMETable_... 
TABLE_TYPE  
ENGINEEngineMySQL extension
VERSIONVersionThe version number of the table's .frm file, MySQL extension
ROW_FORMATRow_formatMySQL extension
TABLE_ROWSRowsMySQL extension
AVG_ROW_LENGTHAvg_row_lengthMySQL extension
DATA_LENGTHData_lengthMySQL extension
MAX_DATA_LENGTHMax_data_lengthMySQL extension
INDEX_LENGTHIndex_lengthMySQL extension
DATA_FREEData_freeMySQL extension
AUTO_INCREMENTAuto_incrementMySQL extension
CREATE_TIMECreate_timeMySQL extension
UPDATE_TIMEUpdate_timeMySQL extension
CHECK_TIMECheck_timeMySQL extension
TABLE_COLLATIONCollationMySQL extension
CHECKSUMChecksumMySQL extension
CREATE_OPTIONSCreate_optionsMySQL extension
TABLE_COMMENTCommentMySQL extension

Notes:

  • TABLE_SCHEMA and TABLE_NAME are a single field in a SHOW display, for example Table_in_db1.

  • TABLE_TYPE should be BASE TABLE or VIEW. Currently, the TABLES table does not list TEMPORARY tables.

  • For partitioned tables, the ENGINE column shows the name of the storage engine used by all partitions. (Previously, this column showed PARTITION for such tables.)

  • The TABLE_ROWS column is NULL if the table is in the INFORMATION_SCHEMA database.

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

  • The DATA_FREE column shows the free space in bytes for InnoDB tables.

  • We have nothing for the table's default character set. TABLE_COLLATION is close, because collation names begin with a character set name.

  • The CREATE_OPTIONS column shows partitioned if the table is partitioned.

The following statements are equivalent:

SELECT table_name FROM INFORMATION_SCHEMA.TABLES
  WHERE table_schema = 'db_name'
  [AND table_name LIKE 'wild']

SHOW TABLES
  FROM db_name
  [LIKE 'wild']

20.3. The INFORMATION_SCHEMA COLUMNS Table

The COLUMNS table provides information about columns in tables.

INFORMATION_SCHEMA NameSHOW NameRemarks
TABLE_CATALOG def
TABLE_SCHEMA  
TABLE_NAME  
COLUMN_NAMEField 
ORDINAL_POSITION see notes
COLUMN_DEFAULTDefault 
IS_NULLABLENull 
DATA_TYPEType 
CHARACTER_MAXIMUM_LENGTHType 
CHARACTER_OCTET_LENGTH  
NUMERIC_PRECISIONType 
NUMERIC_SCALEType 
CHARACTER_SET_NAME  
COLLATION_NAMECollation 
COLUMN_TYPETypeMySQL extension
COLUMN_KEYKeyMySQL extension
EXTRAExtraMySQL extension
PRIVILEGESPrivilegesMySQL extension
COLUMN_COMMENTCommentMySQL extension

Notes:

  • In SHOW, the Type display includes values from several different COLUMNS columns.

  • ORDINAL_POSITION is necessary because you might want to say ORDER BY ORDINAL_POSITION. Unlike SHOW, SELECT does not have automatic ordering.

  • CHARACTER_OCTET_LENGTH should be the same as CHARACTER_MAXIMUM_LENGTH, except for multi-byte character sets.

  • CHARACTER_SET_NAME can be derived from Collation. For example, if you say SHOW FULL COLUMNS FROM t, and you see in the Collation column a value of latin1_swedish_ci, the character set is what is before the first underscore: latin1.

The following statements are nearly equivalent:

SELECT COLUMN_NAME, DATA_TYPE, IS_NULLABLE, COLUMN_DEFAULT
  FROM INFORMATION_SCHEMA.COLUMNS
  WHERE table_name = 'tbl_name'
  [AND table_schema = 'db_name']
  [AND column_name LIKE 'wild']

SHOW COLUMNS
  FROM tbl_name
  [FROM db_name]
  [LIKE 'wild']

20.4. The INFORMATION_SCHEMA STATISTICS Table

The STATISTICS table provides information about table indexes.

INFORMATION_SCHEMA NameSHOW NameRemarks
TABLE_CATALOG def
TABLE_SCHEMA = Database
TABLE_NAMETable 
NON_UNIQUENon_unique 
INDEX_SCHEMA = Database
INDEX_NAMEKey_name 
SEQ_IN_INDEXSeq_in_index 
COLUMN_NAMEColumn_name 
COLLATIONCollation 
CARDINALITYCardinality 
SUB_PARTSub_partMySQL extension
PACKEDPackedMySQL extension
NULLABLENullMySQL extension
INDEX_TYPEIndex_typeMySQL extension
COMMENTCommentMySQL extension

Notes:

  • There is no standard table for indexes. The preceding list is similar to what SQL Server 2000 returns for sp_statistics, except that we replaced the name QUALIFIER with CATALOG and we replaced the name OWNER with SCHEMA.

    Clearly, the preceding table and the output from SHOW INDEX are derived from the same parent. So the correlation is already close.

The following statements are equivalent:

SELECT * FROM INFORMATION_SCHEMA.STATISTICS
  WHERE table_name = 'tbl_name'
  AND table_schema = 'db_name'

SHOW INDEX
  FROM tbl_name
  FROM db_name

20.5. The INFORMATION_SCHEMA USER_PRIVILEGES Table

The USER_PRIVILEGES table provides information about global privileges. This information comes from the mysql.user grant table.

INFORMATION_SCHEMA NameSHOW NameRemarks
GRANTEE 'user_name'@'host_name' value, MySQL extension
TABLE_CATALOG def, MySQL extension
PRIVILEGE_TYPE MySQL extension
IS_GRANTABLE MySQL extension

Notes:

  • This is a nonstandard table. It takes its values from the mysql.user table.

20.6. The INFORMATION_SCHEMA SCHEMA_PRIVILEGES Table

The SCHEMA_PRIVILEGES table provides information about schema (database) privileges. This information comes from the mysql.db grant table.

INFORMATION_SCHEMA NameSHOW NameRemarks
GRANTEE 'user_name'@'host_name' value, MySQL extension
TABLE_CATALOG def, MySQL extension
TABLE_SCHEMA MySQL extension
PRIVILEGE_TYPE MySQL extension
IS_GRANTABLE MySQL extension

Notes:

  • This is a nonstandard table. It takes its values from the mysql.db table.

20.7. The INFORMATION_SCHEMA TABLE_PRIVILEGES Table

The TABLE_PRIVILEGES table provides information about table privileges. This information comes from the mysql.tables_priv grant table.

INFORMATION_SCHEMA NameSHOW NameRemarks
GRANTEE 'user_name'@'host_name' value
TABLE_CATALOG def
TABLE_SCHEMA  
TABLE_NAME  
PRIVILEGE_TYPE  
IS_GRANTABLE  

Notes:

The following statements are not equivalent:

SELECT ... FROM INFORMATION_SCHEMA.TABLE_PRIVILEGES

SHOW GRANTS ...

20.8. The INFORMATION_SCHEMA COLUMN_PRIVILEGES Table

The COLUMN_PRIVILEGES table provides information about column privileges. This information comes from the mysql.columns_priv grant table.

INFORMATION_SCHEMA NameSHOW NameRemarks
GRANTEE 'user_name'@'host_name' value
TABLE_CATALOG def
TABLE_SCHEMA  
TABLE_NAME  
COLUMN_NAME  
PRIVILEGE_TYPE  
IS_GRANTABLE  

Notes:

  • In the output from SHOW FULL COLUMNS, the privileges are all in one field and in lowercase, for example, select,insert,update,references. In COLUMN_PRIVILEGES, there is one privilege per row, in uppercase.

  • PRIVILEGE_TYPE can contain one (and only one) of these values: SELECT, INSERT, UPDATE, REFERENCES.

  • If the user has GRANT OPTION privilege, IS_GRANTABLE should be YES. Otherwise, IS_GRANTABLE should be NO. The output does not list GRANT OPTION as a separate privilege.

The following statements are not equivalent:

SELECT ... FROM INFORMATION_SCHEMA.COLUMN_PRIVILEGES

SHOW GRANTS ...

20.9. The INFORMATION_SCHEMA CHARACTER_SETS Table

The CHARACTER_SETS table provides information about available character sets.

INFORMATION_SCHEMA NameSHOW NameRemarks
CHARACTER_SET_NAMECharset 
DEFAULT_COLLATE_NAMEDefault collation 
DESCRIPIONDescriptionMySQL extension
MAXLENMaxlenMySQL extension

The following statements are equivalent:

SELECT * FROM INFORMATION_SCHEMA.CHARACTER_SETS
  [WHERE CHARACTER_SET_NAME LIKE 'wild']

SHOW CHARACTER SET
  [LIKE 'wild']

20.10. The INFORMATION_SCHEMA COLLATIONS Table

The COLLATIONS table provides information about collations for each character set.

INFORMATION_SCHEMA NameSHOW NameRemarks
COLLATION_NAMECollation 
CHARACTER_SET_NAMECharsetMySQL extension
IDIdMySQL extension
IS_DEFAULTDefaultMySQL extension
IS_COMPILEDCompiledMySQL extension
SORTLENSortlenMySQL extension
  • COLLATION_NAME is the collation name.

  • CHARACTER_SET_NAME is the name of the character set with which the collation is associated.

  • ID is the collation ID.

  • IS_DEFAULT indicates whether the collation is the default for its character set.

  • IS_COMPILED indicates whether the character set is compiled into the server.

  • SORTLEN is related to the amount of memory required to sort strings expressed in the character set.

Collation information is also available from the SHOW COLLATION statement. The following statements are equivalent:

SELECT COLLATION_NAME FROM INFORMATION_SCHEMA.COLLATIONS
  [WHERE COLLATION_NAME LIKE 'wild']

SHOW COLLATION
  [LIKE 'wild']

20.11. The INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY Table

The COLLATION_CHARACTER_SET_APPLICABILITY table indicates what character set is applicable for what collation. The columns are equivalent to the first two display fields that we get from SHOW COLLATION.

INFORMATION_SCHEMA NameSHOW NameRemarks
COLLATION_NAMECollation 
CHARACTER_SET_NAMECharset 

20.12. The INFORMATION_SCHEMA TABLE_CONSTRAINTS Table

The TABLE_CONSTRAINTS table describes which tables have constraints.

INFORMATION_SCHEMA NameSHOW NameRemarks
CONSTRAINT_CATALOG def
CONSTRAINT_SCHEMA  
CONSTRAINT_NAME  
TABLE_SCHEMA  
TABLE_NAME  
CONSTRAINT_TYPE  

Notes:

  • The CONSTRAINT_TYPE value can be UNIQUE, PRIMARY KEY, or FOREIGN KEY.

  • The UNIQUE and PRIMARY KEY information is about the same as what you get from the Key_name field in the output from SHOW INDEX when the Non_unique field is 0.

  • The CONSTRAINT_TYPE column can contain one of these values: UNIQUE, PRIMARY KEY, FOREIGN KEY, CHECK. This is a CHAR (not ENUM) column. The CHECK value is not available until we support CHECK.

20.13. The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table

The KEY_COLUMN_USAGE table describes which key columns have constraints.

INFORMATION_SCHEMA NameSHOW NameRemarks
CONSTRAINT_CATALOG def
CONSTRAINT_SCHEMA  
CONSTRAINT_NAME  
TABLE_CATALOG def
TABLE_SCHEMA  
TABLE_NAME  
COLUMN_NAME  
ORDINAL_POSITION  
POSITION_IN_UNIQUE_CONSTRAINT  
REFERENCED_TABLE_SCHEMA  
REFERENCED_TABLE_NAME  
REFERENCED_COLUMN_NAME  

Notes:

  • If the constraint is a foreign key, then this is the column of the foreign key, not the column that the foreign key references.

  • The value of ORDINAL_POSITION is the column's position within the constraint, not the column's position within the table. Column positions are numbered beginning with 1.

  • The value of POSITION_IN_UNIQUE_CONSTRAINT is NULL for unique and primary-key constraints. For foreign-key constraints, it is the ordinal position in key of the table that is being referenced.

    Suppose that there are two tables name t1 and t3 that have the following definitions:

    CREATE TABLE t1
    (
        s1 INT,
        s2 INT,
        s3 INT,
        PRIMARY KEY(s3)
    ) ENGINE=InnoDB;
    
    CREATE TABLE t3
    (
        s1 INT,
        s2 INT,
        s3 INT,
        KEY(s1),
        CONSTRAINT CO FOREIGN KEY (s2) REFERENCES t1(s3)
    ) ENGINE=InnoDB;
    

    For those two tables, the KEY_COLUMN_USAGE table has two rows:

    • One row with CONSTRAINT_NAME = 'PRIMARY', TABLE_NAME = 't1', COLUMN_NAME = 's3', ORDINAL_POSITION = 1, POSITION_IN_UNIQUE_CONSTRAINT = NULL.

    • One row with CONSTRAINT_NAME = 'CO', TABLE_NAME = 't3', COLUMN_NAME = 's2', ORDINAL_POSITION = 1, POSITION_IN_UNIQUE_CONSTRAINT = 1.

20.14. The INFORMATION_SCHEMA ROUTINES Table

The ROUTINES table provides information about stored routines (both procedures and functions). The ROUTINES table does not include user-defined functions (UDFs) at this time.

The column named “mysql.proc name” indicates the mysql.proc table column that corresponds to the INFORMATION_SCHEMA.ROUTINES table column, if any.

INFORMATION_SCHEMA Namemysql.proc NameRemarks
SPECIFIC_NAMEspecific_name 
ROUTINE_CATALOG def
ROUTINE_SCHEMAdb 
ROUTINE_NAMEname 
ROUTINE_TYPEtype{PROCEDURE|FUNCTION}
DATA_TYPE same as for COLUMNS table
CHARACTER_MAXIMUM_LENGTH same as for COLUMNS table
CHARACTER_OCTET_LENGTH same as for COLUMNS table
NUMERIC_PRECISION same as for COLUMNS table
NUMERIC_SCALE same as for COLUMNS table
CHARACTER_SET_NAME same as for COLUMNS table
COLLATION_NAME same as for COLUMNS table
DTD_IDENTIFIER data type descriptor
ROUTINE_BODY SQL
ROUTINE_DEFINITIONbody 
EXTERNAL_NAME NULL
EXTERNAL_LANGUAGElanguageNULL
PARAMETER_STYLE SQL
IS_DETERMINISTICis_deterministic 
SQL_DATA_ACCESSsql_data_access 
SQL_PATH NULL
SECURITY_TYPEsecurity_type 
CREATEDcreated 
LAST_ALTEREDmodified 
SQL_MODEsql_modeMySQL extension
ROUTINE_COMMENTcommentMySQL extension
DEFINERdefinerMySQL extension
CHARACTER_SET_CLIENT MySQL extension
COLLATION_CONNECTION MySQL extension
DATABASE_COLLATION MySQL extension

Notes:

  • MySQL calculates EXTERNAL_LANGUAGE thus:

    • If mysql.proc.language='SQL', EXTERNAL_LANGUAGE is NULL

    • Otherwise, EXTERNAL_LANGUAGE is what is in mysql.proc.language. However, we do not have external languages yet, so it is always NULL.

  • CHARACTER_SET_CLIENT is the session value of the character_set_client system variable when the routine was created. COLLATION_CONNECTION is the session value of the collation_connection system variable when the routine was created. DATABASE_COLLATION is the collation of the database with which the routine is associated.

  • The DATA_TYPE, CHARACTER_MAXIMUM_LENGTH, CHARACTER_OCTET_LENGTH, NUMERIC_PRECISION, NUMERIC_SCALE, CHARACTER_SET_NAME, and COLLATION_NAME columns provide information about the data type for the RETURNS clause of stored functions. If a stored routine is a stored procedure, these columns all are NULL. These columns were added in MySQL 5.5.3.

    Information about stored function RETURNS data types is also available in the PARAMETERS table. The return value data type row for a function can be identified as the row that has an ORDINAL_POSITION value of 0.

20.15. The INFORMATION_SCHEMA VIEWS Table

The VIEWS table provides information about views in databases. You must have the SHOW VIEW privilege to access this table.

INFORMATION_SCHEMA NameSHOW NameRemarks
TABLE_CATALOG def
TABLE_SCHEMA  
TABLE_NAME  
VIEW_DEFINITION  
CHECK_OPTION  
IS_UPDATABLE  
DEFINER  
SECURITY_TYPE  
CHARACTER_SET_CLIENT MySQL extension
COLLATION_CONNECTION MySQL extension

Notes:

  • The VIEW_DEFINITION column has most of what you see in the Create Table field that SHOW CREATE VIEW produces. Skip the words before SELECT and skip the words WITH CHECK OPTION. Suppose that the original statement was:

    CREATE VIEW v AS
      SELECT s2,s1 FROM t
      WHERE s1 > 5
      ORDER BY s1
      WITH CHECK OPTION;
    

    Then the view definition looks like this:

    SELECT s2,s1 FROM t WHERE s1 > 5 ORDER BY s1
    
  • The CHECK_OPTION column has a value of NONE, CASCADE, or LOCAL.

  • MySQL sets a flag, called the view updatability flag, at CREATE VIEW time. The flag is set to YES (true) if UPDATE and DELETE (and similar operations) are legal for the view. Otherwise, the flag is set to NO (false). The IS_UPDATABLE column in the VIEWS table displays the status of this flag. It means that the server always knows whether a view is updatable. If the view is not updatable, statements such UPDATE, DELETE, and INSERT are illegal and will be rejected. (Note that even if a view is updatable, it might not be possible to insert into it; for details, refer to Section 12.1.16, “CREATE VIEW Syntax”.)

  • The DEFINER column indicates who defined the view. SECURITY_TYPE has a value of DEFINER or INVOKER.

  • CHARACTER_SET_CLIENT is the session value of the character_set_client system variable when the view was created. COLLATION_CONNECTION is the session value of the collation_connection system variable when the view was created.

MySQL lets you use different sql_mode settings to tell the server the type of SQL syntax to support. For example, you might use the ANSI SQL mode to ensure MySQL correctly interprets the standard SQL concatenation operator, the double bar (||), in your queries. If you then create a view that concatenates items, you might worry that changing the sql_mode setting to a value different from ANSI could cause the view to become invalid. But this is not the case. No matter how you write out a view definition, MySQL always stores it the same way, in a canonical form. Here is an example that shows how the server changes a double bar concatenation operator to a CONCAT() function:

mysql> SET sql_mode = 'ANSI';
Query OK, 0 rows affected (0.00 sec)

mysql> CREATE VIEW test.v AS SELECT 'a' || 'b' as col1;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT VIEW_DEFINITION FROM INFORMATION_SCHEMA.VIEWS
    -> WHERE TABLE_SCHEMA = 'test' AND TABLE_NAME = 'v';
+----------------------------------+
| VIEW_DEFINITION                  |
+----------------------------------+
| select concat('a','b') AS `col1` |
+----------------------------------+
1 row in set (0.00 sec)

The advantage of storing a view definition in canonical form is that changes made later to the value of sql_mode will not affect the results from the view. However an additional consequence is that comments prior to SELECT are stripped from the definition by the server.

20.16. The INFORMATION_SCHEMA TRIGGERS Table

The TRIGGERS table provides information about triggers. You can see results only for databases and tables for which you have the TRIGGER privilege.

INFORMATION_SCHEMA NameSHOW NameRemarks
TRIGGER_CATALOG def
TRIGGER_SCHEMA  
TRIGGER_NAMETrigger 
EVENT_MANIPULATIONEvent 
EVENT_OBJECT_CATALOG def
EVENT_OBJECT_SCHEMA  
EVENT_OBJECT_TABLETable 
ACTION_ORDER 0
ACTION_CONDITION NULL
ACTION_STATEMENTStatement 
ACTION_ORIENTATION ROW
ACTION_TIMINGTiming 
ACTION_REFERENCE_OLD_TABLE NULL
ACTION_REFERENCE_NEW_TABLE NULL
ACTION_REFERENCE_OLD_ROW OLD
ACTION_REFERENCE_NEW_ROW NEW
CREATED NULL (0)
SQL_MODE MySQL extension
DEFINER MySQL extension
CHARACTER_SET_CLIENT MySQL extension
COLLATION_CONNECTION MySQL extension
DATABASE_COLLATION MySQL extension

Notes:

  • The TRIGGER_SCHEMA and TRIGGER_NAME columns contain the name of the database in which the trigger occurs and the trigger name, respectively.

  • The EVENT_MANIPULATION column contains one of the values 'INSERT', 'DELETE', or 'UPDATE'.

  • As noted in Section 19.3, “Using Triggers”, every trigger is associated with exactly one table. The EVENT_OBJECT_SCHEMA and EVENT_OBJECT_TABLE columns contain the database in which this table occurs, and the table's name.

  • The ACTION_ORDER column contains the ordinal position of the trigger's action within the list of all similar triggers on the same table. Currently, this value is always 0, because it is not possible to have more than one trigger with the same EVENT_MANIPULATION and ACTION_TIMING on the same table.

  • The ACTION_STATEMENT column contains the statement to be executed when the trigger is invoked. This is the same as the text displayed in the Statement column of the output from SHOW TRIGGERS. Note that this text uses UTF-8 encoding.

  • The ACTION_ORIENTATION column always contains the value 'ROW'.

  • The ACTION_TIMING column contains one of the two values 'BEFORE' or 'AFTER'.

  • The columns ACTION_REFERENCE_OLD_ROW and ACTION_REFERENCE_NEW_ROW contain the old and new column identifiers, respectively. This means that ACTION_REFERENCE_OLD_ROW always contains the value 'OLD' and ACTION_REFERENCE_NEW_ROW always contains the value 'NEW'.

  • The SQL_MODE column shows the server SQL mode that was in effect at the time when the trigger was created (and thus which remains in effect for this trigger whenever it is invoked, regardless of the current server SQL mode). The possible range of values for this column is the same as that of the sql_mode system variable. See Section 5.1.7, “Server SQL Modes”.

  • The DEFINER column indicates who defined the trigger.

  • CHARACTER_SET_CLIENT is the session value of the character_set_client system variable when the trigger was created. COLLATION_CONNECTION is the session value of the collation_connection system variable when the trigger was created. DATABASE_COLLATION is the collation of the database with which the trigger is associated.

  • The following columns currently always contain NULL: ACTION_CONDITION, ACTION_REFERENCE_OLD_TABLE, ACTION_REFERENCE_NEW_TABLE, and CREATED.

Example, using the ins_sum trigger defined in Section 19.3, “Using Triggers”:

mysql> SELECT * FROM INFORMATION_SCHEMA.TRIGGERS\G
*************************** 1. row ***************************
           TRIGGER_CATALOG: def
            TRIGGER_SCHEMA: test
              TRIGGER_NAME: ins_sum
        EVENT_MANIPULATION: INSERT
      EVENT_OBJECT_CATALOG: def
       EVENT_OBJECT_SCHEMA: test
        EVENT_OBJECT_TABLE: account
              ACTION_ORDER: 0
          ACTION_CONDITION: NULL
          ACTION_STATEMENT: SET @sum = @sum + NEW.amount
        ACTION_ORIENTATION: ROW
             ACTION_TIMING: BEFORE
ACTION_REFERENCE_OLD_TABLE: NULL
ACTION_REFERENCE_NEW_TABLE: NULL
  ACTION_REFERENCE_OLD_ROW: OLD
  ACTION_REFERENCE_NEW_ROW: NEW
                   CREATED: NULL
                  SQL_MODE:
                   DEFINER: me@localhost

See also Section 12.4.5.39, “SHOW TRIGGERS Syntax”.

20.17. The INFORMATION_SCHEMA PLUGINS Table

The PLUGINS table provides information about server plugins.

INFORMATION_SCHEMA NameSHOW NameRemarks
PLUGIN_NAMENameMySQL extension
PLUGIN_VERSION MySQL extension
PLUGIN_STATUSStatusMySQL extension
PLUGIN_TYPETypeMySQL extension
PLUGIN_TYPE_VERSION MySQL extension
PLUGIN_LIBRARYLibraryMySQL extension
PLUGIN_LIBRARY_VERSION MySQL extension
PLUGIN_AUTHOR MySQL extension
PLUGIN_DESCRIPTION MySQL extension
PLUGIN_LICENSE MySQL extension

Notes:

  • The PLUGINS table is a nonstandard table.

  • PLUGIN_NAME is the name used to refer to the plugin in statements such as INSTALL PLUGIN and UNINSTALL PLUGIN.

  • PLUGIN_VERSION is the version from the plugin's general type descriptor.

  • PLUGIN_STATUS indicates the plugin status, one of ACTIVE, INACTIVE, DISABLED, or DELETED.

  • PLUGIN_TYPE indicates the type of plugin, such as STORAGE ENGINE or INFORMATION_SCHEMA.

  • PLUGIN_TYPE_VERSION is the version from the plugin's type-specific descriptor.

  • PLUGIN_LIBRARY is the name of the plugin shared object file. This is the name used to refer to the plugin file in statements such as INSTALL PLUGIN and UNINSTALL PLUGIN. This file is located in the directory named by the plugin_dir system variable. If the library name is NULL, the plugin is compiled in and cannot be uninstalled with UNINSTALL PLUGIN.

  • PLUGIN_LIBRARY_VERSION indicates the plugin API interface version.

  • PLUGIN_AUTHOR names the plugin author.

  • PLUGIN_DESCRIPTION provides a short description of the plugin.

  • PLUGIN_LICENSE indicates how the plugin is licensed; for example, GPL.

For plugins installed with INSTALL PLUGIN, the PLUGIN_NAME and PLUGIN_LIBARY values are also registered in the mysql.plugin table.

These statements are equivalent:

SELECT
  PLUGIN_NAME, PLUGIN_STATUS, PLUGIN_TYPE,
  PLUGIN_LIBRARY, PLUGIN_LICENSE
FROM INFORMATION_SCHEMA.PLUGINS;

SHOW PLUGINS;

For information about plugin data structures that form the basis of the information in the PLUGINS table, see Section 23.2, “The MySQL Plugin API”.

Plugin information is also available using the SHOW PLUGINS statement. See Section 12.4.5.26, “SHOW PLUGINS Syntax”.

20.18. The INFORMATION_SCHEMA ENGINES Table

The PLUGINS table provides information about storage engines.

INFORMATION_SCHEMA NameSHOW NameRemarks
ENGINEEngineMySQL extension
SUPPORTSupportMySQL extension
COMMENTCommentMySQL extension
TRANSACTIONSTransactionsMySQL extension
XAXAMySQL extension
SAVEPOINTSSavepointsMySQL extension

Notes:

  • The ENGINES table is a nonstandard table.

See also Section 12.4.5.17, “SHOW ENGINES Syntax”.

20.19. The INFORMATION_SCHEMA PARTITIONS Table

The PARTITIONS table provides information about table partitions. See Chapter 18, Partitioning, for more information about partitioning tables.

INFORMATION_SCHEMA NameSHOW NameRemarks
TABLE_CATALOG MySQL extension
TABLE_SCHEMA MySQL extension
TABLE_NAME MySQL extension
PARTITION_NAME MySQL extension
SUBPARTITION_NAME MySQL extension
PARTITION_ORDINAL_POSITION MySQL extension
SUBPARTITION_ORDINAL_POSITION MySQL extension
PARTITION_METHOD MySQL extension
SUBPARTITION_METHOD MySQL extension
PARTITION_EXPRESSION MySQL extension
SUBPARTITION_EXPRESSION MySQL extension
PARTITION_DESCRIPTION MySQL extension
TABLE_ROWS MySQL extension
AVG_ROW_LENGTH MySQL extension
DATA_LENGTH MySQL extension
MAX_DATA_LENGTH MySQL extension
INDEX_LENGTH MySQL extension
DATA_FREE MySQL extension
CREATE_TIME MySQL extension
UPDATE_TIME MySQL extension
CHECK_TIME MySQL extension
CHECKSUM MySQL extension
PARTITION_COMMENT MySQL extension
NODEGROUP MySQL extension
TABLESPACE_NAME MySQL extension

Notes:

  • The PARTITIONS table is a nonstandard table.

    Each record in this table corresponds to an individual partition or subpartition of a partitioned table.

  • TABLE_CATALOG: This column is always def.

  • TABLE_SCHEMA: This column contains the name of the database to which the table belongs.

  • TABLE_NAME: This column contains the name of the table containing the partition.

  • PARTITION_NAME: The name of the partition.

  • SUBPARTITION_NAME: If the PARTITIONS table record represents a subpartition, then this column contains the name of subpartition; otherwise it is NULL.

  • PARTITION_ORDINAL_POSITION: All partitions are indexed in the same order as they are defined, with 1 being the number assigned to the first partition. The indexing can change as partitions are added, dropped, and reorganized; the number shown is this column reflects the current order, taking into account any indexing changes.

  • SUBPARTITION_ORDINAL_POSITION: Subpartitions within a given partition are also indexed and reindexed in the same manner as partitions are indexed within a table.

  • PARTITION_METHOD: One of the values RANGE, LIST, HASH, LINEAR HASH, KEY, or LINEAR KEY; that is, one of the available partitioning types as discussed in Section 18.2, “Partitioning Types”.

  • SUBPARTITION_METHOD: One of the values HASH, LINEAR HASH, KEY, or LINEAR KEY; that is, one of the available subpartitioning types as discussed in Section 18.2.6, “Subpartitioning”.

  • PARTITION_EXPRESSION: This is the expression for the partitioning function used in the CREATE TABLE or ALTER TABLE statement that created the table's current partitioning scheme.

    For example, consider a partitioned table created in the test database using this statement:

    CREATE TABLE tp (
        c1 INT,
        c2 INT,
        c3 VARCHAR(25)
    )
    PARTITION BY HASH(c1 + c2)
    PARTITIONS 4;
    

    The PARTITION_EXPRESSION column in a PARTITIONS table record for a partition from this table displays c1 + c2, as shown here:

    mysql> SELECT DISTINCT PARTITION_EXPRESSION
         >     FROM INFORMATION_SCHEMA.PARTITIONS
         >     WHERE TABLE_NAME='tp' AND TABLE_SCHEMA='test';
    +----------------------+
    | PARTITION_EXPRESSION |
    +----------------------+
    | c1 + c2              |
    +----------------------+
    1 row in set (0.09 sec)
    
  • SUBPARTITION_EXPRESSION: 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, then this column is NULL.

  • PARTITION_DESCRIPTION: 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 comma-separated list of integer values.

    For partitions whose PARTITION_METHOD is other than RANGE or LIST, this column is always NULL.

  • TABLE_ROWS: The number of table rows in the partition.

    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.

  • AVG_ROW_LENGTH: 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.

  • DATA_LENGTH: 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.

  • MAX_DATA_LENGTH: The maximum number of bytes that can be stored in this partition or subpartition.

  • INDEX_LENGTH: The length of the index file for this partition or subpartition, in bytes.

  • DATA_FREE: The number of bytes allocated to the partition or subpartition but not used.

  • CREATE_TIME: The time of the partition's or subpartition's creation.

  • UPDATE_TIME: The time that the partition or subpartition was last modified.

  • CHECK_TIME: The last time that the table to which this partition or subpartition belongs was checked.

    Note

    Some storage engines do not update this time; for tables using these storage engines, this value is always NULL.

  • CHECKSUM: The checksum value, if any; otherwise, this column is NULL.

  • PARTITION_COMMENT: This column contains the text of any comment made for the partition.

    The default value for this column is an empty string.

  • NODEGROUP: This is the nodegroup to which the partition belongs. This is relevant only to MySQL Cluster tables; otherwise the value of this column is always 0.

  • TABLESPACE_NAME: This column contains the name of the tablespace to which the partition belongs. Currently, the value of this column is always DEFAULT.

  • A nonpartitioned table has one record in INFORMATION_SCHEMA.PARTITIONS; however, the values of the PARTITION_NAME, SUBPARTITION_NAME, PARTITION_ORDINAL_POSITION, SUBPARTITION_ORDINAL_POSITION, PARTITION_METHOD, SUBPARTITION_METHOD, PARTITION_EXPRESSION, SUBPARTITION_EXPRESSION, and PARTITION_DESCRIPTION columns are all NULL. (The PARTITION_COMMENT column in this case is blank.)

20.20. The INFORMATION_SCHEMA EVENTS Table

The EVENTS table provides information about scheduled events, which are discussed in Section 19.4, “Using the Event Scheduler”. The SHOW Name values correspond to column names of the SHOW EVENTS statement.

INFORMATION_SCHEMA NameSHOW NameRemarks
EVENT_CATALOG def, MySQL extension
EVENT_SCHEMADbMySQL extension
EVENT_NAMENameMySQL extension
DEFINERDefinerMySQL extension
TIME_ZONETime zoneMySQL extension
EVENT_BODY MySQL extension
EVENT_DEFINITION MySQL extension
EVENT_TYPETypeMySQL extension
EXECUTE_ATExecute atMySQL extension
INTERVAL_VALUEInterval valueMySQL extension
INTERVAL_FIELDInterval fieldMySQL extension
SQL_MODE MySQL extension
STARTSStartsMySQL extension
ENDSEndsMySQL extension
STATUSStatusMySQL extension
ON_COMPLETION MySQL extension
CREATED MySQL extension
LAST_ALTERED MySQL extension
LAST_EXECUTED MySQL extension
EVENT_COMMENT MySQL extension
ORIGINATOROriginatorMySQL extension
CHARACTER_SET_CLIENTcharacter_set_clientMySQL extension
COLLATION_CONNECTIONcollation_connectionMySQL extension
DATABASE_COLLATIONDatabase CollationMySQL extension

Notes:

  • The EVENTS table is a nonstandard table.

  • EVENT_CATALOG: The value of this column is always def.

  • EVENT_SCHEMA: The name of the schema (database) to which this event belongs.

  • EVENT_NAME: The name of the event.

  • DEFINER: The account of the user who created the event, in 'user_name'@'host_name' format.

  • TIME_ZONE: The event time zone, which is the time zone used for scheduling the event and that is in effect within the event as it executes. The default value is SYSTEM.

  • EVENT_BODY: The language used for the statements in the event's DO clause; in MySQL 5.5, this is always SQL.

    This column is not to be confused with the column of the same name (now named EVENT_DEFINITION) that existed in earlier MySQL versions.

  • EVENT_DEFINITION: The text of the SQL statement making up the event's DO clause; in other words, the statement executed by this event.

  • EVENT_TYPE: The event repetition type, either ONE TIME (transient) or RECURRING (repeating).

  • EXECUTE_AT: For a one-time event, this is the DATETIME value specified in the AT clause of the CREATE EVENT statement used to create the event, or of the last ALTER EVENT statement that modified the event. The value shown in this column reflects the addition or subtraction of any INTERVAL value included in the event's AT clause. For example, if an event is created using ON SCHEDULE AT CURRENT_TIMESTAMP + '1:6' DAY_HOUR, and the event was created at 2006-02-09 14:05:30, the value shown in this column would be '2006-02-10 20:05:30'.

    If the event's timing is determined by an EVERY clause instead of an AT clause (that is, if the event is recurring), the value of this column is NULL.

  • INTERVAL_VALUE: For recurring events, this column contains the numeric portion of the event's EVERY clause.

    For a one-time event (that is, an event whose timing is determined by an AT clause), this column is NULL.

  • INTERVAL_FIELD: For recurring events, this column contains the units portion of the EVERY clause governing the timing of the event. Thus, this column contains a value such as 'YEAR', 'QUARTER', 'DAY', and so on.

    For a one-time event (that is, an event whose timing is determined by an AT clause), this column is NULL.

  • SQL_MODE: The SQL mode in effect at the time the event was created or altered.

  • STARTS: For a recurring event whose definition includes a STARTS clause, this column contains the corresponding DATETIME value. As with the EXECUTE_AT column, this value resolves any expressions used.

    If there is no STARTS clause affecting the timing of the event, this column is NULL

  • ENDS: For a recurring event whose definition includes a ENDS clause, this column contains the corresponding DATETIME value. As with the EXECUTE_AT column, this value resolves any expressions used.

    If there is no ENDS clause affecting the timing of the event, this column is NULL.

  • STATUS: One of the three values ENABLED, DISABLED, or SLAVESIDE_DISABLED.

    SLAVESIDE_DISABLED indicates that the creation of the event occurred on another MySQL server acting as a replication master and was replicated to the current MySQL server which is acting as a slave, but the event is not presently being executed on the slave. See Section 17.4.1.8, “Replication of Invoked Features”, for more information.

  • ON_COMPLETION: One of the two values PRESERVE or NOT PRESERVE.

  • CREATED: The date and time when the event was created. This is a DATETIME value.

  • LAST_ALTERED: The date and time when the event was last modified. This is a DATETIME value. If the event has not been modified since its creation, this column holds the same value as the CREATED column.

  • LAST_EXECUTED: The date and time when the event last executed. A DATETIME value. If the event has never executed, this column is NULL.

    LAST_EXECUTED indicates when the event started. As a result, the ENDS column is never less than LAST_EXECUTED.

  • EVENT_COMMENT: The text of a comment, if the event has one. If not, the value of this column is an empty string.

  • ORIGINATOR: The server ID of the MySQL server on which the event was created; used in replication. The default value is 0.

  • CHARACTER_SET_CLIENT is the session value of the character_set_client system variable when the event was created. COLLATION_CONNECTION is the session value of the collation_connection system variable when the event was created. DATABASE_COLLATION is the collation of the database with which the event is associated.

Example: Suppose that the user jon@ghidora creates an event named e_daily, and then modifies it a few minutes later using an ALTER EVENT statement, as shown here:

DELIMITER |

CREATE EVENT e_daily
    ON SCHEDULE
      EVERY 1 DAY
    COMMENT 'Saves total number of sessions then clears the table each day'
    DO
      BEGIN
        INSERT INTO site_activity.totals (time, total)
          SELECT CURRENT_TIMESTAMP, COUNT(*)
            FROM site_activity.sessions;
        DELETE FROM site_activity.sessions;
      END |

DELIMITER ;

ALTER EVENT e_daily
    ENABLED;

(Note that comments can span multiple lines.)

This user can then run the following SELECT statement, and obtain the output shown:

mysql> SELECT * FROM INFORMATION_SCHEMA.EVENTS
     > WHERE EVENT_NAME = 'e_daily'
     > AND EVENT_SCHEMA = 'myschema'\G
*************************** 1. row ***************************
       EVENT_CATALOG: def
        EVENT_SCHEMA: test
          EVENT_NAME: e_daily
             DEFINER: paul@localhost
           TIME_ZONE: SYSTEM
          EVENT_BODY: SQL
    EVENT_DEFINITION: BEGIN
        INSERT INTO site_activity.totals (time, total)
          SELECT CURRENT_TIMESTAMP, COUNT(*)
            FROM site_activity.sessions;
        DELETE FROM site_activity.sessions;
      END
          EVENT_TYPE: RECURRING
          EXECUTE_AT: NULL
      INTERVAL_VALUE: 1
      INTERVAL_FIELD: DAY
            SQL_MODE:
              STARTS: 2008-09-03 12:13:39
                ENDS: NULL
              STATUS: ENABLED
       ON_COMPLETION: NOT PRESERVE
             CREATED: 2008-09-03 12:13:39
        LAST_ALTERED: 2008-09-03 12:13:39
       LAST_EXECUTED: NULL
       EVENT_COMMENT: Saves total number of sessions then clears the
                      table each day
          ORIGINATOR: 1
CHARACTER_SET_CLIENT: latin1
COLLATION_CONNECTION: latin1_swedish_ci
  DATABASE_COLLATION: latin1_swedish_ci

Times in the EVENTS table are displayed using the event time zone or the current session time zone, as described in Section 19.4.4, “Event Metadata”.

See also Section 12.4.5.19, “SHOW EVENTS Syntax”.

20.21. The INFORMATION_SCHEMA FILES Table

The FILES table provides information about the files in which MySQL tablespace data is stored.

INFORMATION_SCHEMA NameSHOW NameRemarks
FILE_ID MySQL extension
FILE_NAME MySQL extension
FILE_TYPE MySQL extension
TABLESPACE_NAME MySQL extension
TABLE_CATALOG MySQL extension
TABLE_SCHEMA MySQL extension
TABLE_NAME MySQL extension
LOGFILE_GROUP_NAME MySQL extension
LOGFILE_GROUP_NUMBER MySQL extension
ENGINE MySQL extension
FULLTEXT_KEYS MySQL extension
DELETED_ROWS MySQL extension
UPDATE_COUNT MySQL extension
FREE_EXTENTS MySQL extension
TOTAL_EXTENTS MySQL extension
EXTENT_SIZE MySQL extension
INITIAL_SIZE MySQL extension
MAXIMUM_SIZE MySQL extension
AUTOEXTEND_SIZE MySQL extension
CREATION_TIME MySQL extension
LAST_UPDATE_TIME MySQL extension
LAST_ACCESS_TIME MySQL extension
RECOVER_TIME MySQL extension
TRANSACTION_COUNTER MySQL extension
VERSION MySQL extension
ROW_FORMAT MySQL extension
TABLE_ROWS MySQL extension
AVG_ROW_LENGTH MySQL extension
DATA_LENGTH MySQL extension
MAX_DATA_LENGTH MySQL extension
INDEX_LENGTH MySQL extension
DATA_FREE MySQL extension
CREATE_TIME MySQL extension
UPDATE_TIME MySQL extension
CHECK_TIME MySQL extension
CHECKSUM MySQL extension
STATUS MySQL extension
EXTRA MySQL extension

Notes:

  • FILE_ID column values are auto-generated.

  • FILE_NAME is the name of a data file created by CREATE TABLESPACE or ALTER TABLESPACE.

  • FILE_TYPE is the tablespace file type.

  • TABLESPACE_NAME is the name of the tablespace with which the file is associated.

  • Currently, the value of the TABLESPACE_CATALOG column is always NULL.

  • TABLE_NAME is the name of the table with which the file is associated, if any.

  • The EXTENT_SIZE is always 0.

  • There are no SHOW statements associated with the FILES table.

20.22. The INFORMATION_SCHEMA TABLESPACES Table

The TABLESPACES table provides information about active tablespaces. The table was added in MySQL 5.5.3.

INFORMATION_SCHEMA NameSHOW NameRemarks
TABLESPACE_NAME MySQL extension
ENGINE MySQL extension
TABLESPACE_TYPE MySQL extension
LOGFILE_GROUP_NAME MySQL extension
EXTENT_SIZE MySQL extension
AUTOEXTEND_SIZE MySQL extension
MAXIMUM_SIZE MySQL extension
NODEGROUP_ID MySQL extension
TABLESPACE_COMMENT MySQL extension

20.23. The INFORMATION_SCHEMA PROCESSLIST Table

The PROCESSLIST table provides information about which threads are running.

INFORMATION_SCHEMA NameSHOW NameRemarks
IDIdMySQL extension
USERUserMySQL extension
HOSTHostMySQL extension
DBdbMySQL extension
COMMANDCommandMySQL extension
TIMETimeMySQL extension
STATEStateMySQL extension
INFOInfoMySQL extension

For an extensive description of the table columns, see Section 12.4.5.30, “SHOW PROCESSLIST Syntax”.

Notes:

  • The PROCESSLIST table is a nonstandard table.

  • Like the output from the corresponding SHOW statement, the PROCESSLIST table will only show information about your own threads, unless you have the PROCESS privilege, in which case you will see information about other threads, too. As an anonymous user, you cannot see any rows at all.

  • If an SQL statement refers to INFORMATION_SCHEMA.PROCESSLIST, then MySQL will populate the entire table once, when statement execution begins, so there is read consistency during the statement. There is no read consistency for a multi-statement transaction, though.

The following statements are equivalent:

SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST

SHOW FULL PROCESSLIST

20.24. The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table

The REFERENTIAL_CONSTRAINTS table provides information about foreign keys.

INFORMATION_SCHEMA NameSHOW NameRemarks
CONSTRAINT_CATALOG def
CONSTRAINT_SCHEMA  
CONSTRAINT_NAME  
UNIQUE_CONSTRAINT_CATALOG def
UNIQUE_CONSTRAINT_SCHEMA  
UNIQUE_CONSTRAINT_NAME  
MATCH_OPTION  
UPDATE_RULE  
DELETE_RULE  
TABLE_NAME  
REFERENCED_TABLE_NAME  

Notes:

  • TABLE_NAME has the same value as TABLE_NAME in INFORMATION_SCHEMA.TABLE_CONSTRAINTS.

  • CONSTRAINT_SCHEMA and CONSTRAINT_NAME identify the foreign key.

  • UNIQUE_CONSTRAINT_SCHEMA, UNIQUE_CONSTRAINT_NAME, and REFERENCED_TABLE_NAME identify the referenced key.

  • The only valid value at this time for MATCH_OPTION is NONE.

  • The possible values for UPDATE_RULE or DELETE_RULE are CASCADE, SET NULL, SET DEFAULT, RESTRICT, NO ACTION.

20.25. The INFORMATION_SCHEMA GLOBAL_STATUS and SESSION_STATUS Tables

The GLOBAL_STATUS and SESSION_STATUS tables provide information about server status variables. Their contents correspond to the information produced by the SHOW GLOBAL STATUS and SHOW SESSION STATUS statements (see Section 12.4.5.36, “SHOW STATUS Syntax”).

INFORMATION_SCHEMA NameSHOW NameRemarks
VARIABLE_NAMEVariable_name 
VARIABLE_VALUEValue 

Notes:

  • The VARIABLE_VALUE column for each of these tables is defined as VARCHAR(20480).

20.26. The INFORMATION_SCHEMA GLOBAL_VARIABLES and SESSION_VARIABLES Tables

The GLOBAL_VARIABLES and SESSION_VARIABLES tables provide information about server status variables. Their contents correspond to the information produced by the SHOW GLOBAL VARIABLES and SHOW SESSION VARIABLES statements (see Section 12.4.5.40, “SHOW VARIABLES Syntax”).

INFORMATION_SCHEMA NameSHOW NameRemarks
VARIABLE_NAMEVariable_name 
VARIABLE_VALUEValue 

Notes:

  • The VARIABLE_VALUE column for each of these tables is defined as VARCHAR(20480).

20.27. The INFORMATION_SCHEMA PARAMETERS Table

The PARAMETERS table provides information about stored procedure and function parameters, and about return values for stored functions. Parameter information is similar to the contents of the param_list column in the mysql.proc table.

INFORMATION_SCHEMA Namemysql.proc NameRemarks
SPECIFIC_CATALOG def
SPECIFIC_SCHEMAdbroutine database
SPECIFIC_NAMEnameroutine name
ORDINAL_POSITION 1, 2, 3, ... for parameters, 0 for function RETURNS clause
PARAMETER_MODE IN, OUT, INOUT (NULL for RETURNS)
PARAMETER_NAME parameter name (NULL for RETURNS)
DATA_TYPE same as for COLUMNS table
CHARACTER_MAXIMUM_LENGTH same as for COLUMNS table
CHARACTER_OCTET_LENGTH same as for COLUMNS table
NUMERIC_PRECISION same as for COLUMNS table
NUMERIC_SCALE same as for COLUMNS table
CHARACTER_SET_NAME same as for COLUMNS table
COLLATION_NAME same as for COLUMNS table
DTD_IDENTIFIER same as for COLUMNS table
ROUTINE_TYPEtypesame as for ROUTINES table

Notes:

  • The PARAMETERS table was added in MySQL 5.5.3.

  • For successive parameters of a stored procedure or function, the ORDINAL_POSITION values are 1, 2, 3, and so forth. For a stored function, there is also a row that describes the data type for the RETURNS clause. The return value is not a true parameter, so the row that describes it has these unique characteristics:

    • The ORDINAL_POSITION value is 0.

    • The PARAMETER_NAME and PARAMETER_MODE values are NULL because the return value has no name and the mode does not apply.

20.28. The INFORMATION_SCHEMA PROFILING Table

The PROFILING table provides statement profiling information. Its contents correspond to the information produced by the SHOW PROFILES and SHOW PROFILE statements (see Section 12.4.5.32, “SHOW PROFILES Syntax”). The table is empty unless the profiling session variable is set to 1.

INFORMATION_SCHEMA NameSHOW NameRemarks
QUERY_IDQuery_ID 
SEQ 
STATEStatus 
DURATIONDuration 
CPU_USERCPU_user 
CPU_SYSTEMCPU_system 
CONTEXT_VOLUNTARYContext_voluntary 
CONTEXT_INVOLUNTARYContext_involuntary 
BLOCK_OPS_INBlock_ops_in 
BLOCK_OPS_OUTBlock_ops_out 
MESSAGES_SENTMessages_sent 
MESSAGES_RECEIVEDMessages_received 
PAGE_FAULTS_MAJORPage_faults_major 
PAGE_FAULTS_MINORPage_faults_minor 
SWAPSSwaps 
SOURCE_FUNCTIONSource_function 
SOURCE_FILESource_file 
SOURCE_LINESource_line 

Notes:

  • QUERY_ID is a numeric statement identifier.

  • SEQ is a sequence number indicating the display order for rows with the same QUERY_ID value.

  • STATE is the profiling state to which the row measurements apply.

  • DURATION indicates how long statement execution remained in the given state, in seconds.

  • CPU_USER and CPU_SYSTEM indicate user and system CPU use, in seconds.

  • CONTEXT_VOLUNTARY and CONTEXT_INVOLUNTARY indicate how many voluntary and involuntary context switches occurred.

  • BLOCK_OPS_IN and BLOCK_OPS_OUT indicate the number of block input and output operations.

  • MESSAGES_SENT and MESSAGES_RECEIVED indicate the number of communication messages sent and received.

  • PAGE_FAULTS_MAJOR and PAGE_FAULTS_MINOR indicate the number of major and minor page faults.

  • SWAPS indicates how many swaps occurred.

  • SOURCE_FUNCTION, SOURCE_FILE, and SOURCE_LINE provide information indicating where in the source code the profiled state executes.

20.29. INFORMATION_SCHEMA Tables for InnoDB

The InnoDB tables related to the InnoDB storage engine help you to monitor ongoing InnoDB activity, to detect inefficiencies before they turn into issues, or to troubleshoot performance and capacity issues that do occur. As your database becomes bigger and busier, running up against the limits of your hardware capacity, you monitor and tune these aspects to keep the database running smoothly. The monitoring information deals with:

  • InnoDB table compression, a feature whose use depends on a balance between I/O reduction, CPU usage, buffer pool management, and how much compression is possible for your data.

  • Transactions and locks, features that balance high performance for a single operation, against the ability to run multiple operations concurrently. (Transactions are the high-level, user-visible aspect of concurrency. Locks are the low-level mechanism that transactions use to avoid reading or writing unreliable data.)

20.29.1. The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables

The INNODB_CMP and INNODB_CMP_RESET tables contain status information on operations related to compressed InnoDB tables.

Table 20.1. Columns of INNODB_CMP and INNODB_CMP_RESET

Column nameDescription
PAGE_SIZECompressed page size in bytes.
COMPRESS_OPSNumber of times a B-tree page of the size PAGE_SIZE has been compressed. Pages are compressed whenever an empty page is created or the space for the uncompressed modification log runs out.
COMPRESS_OPS_OKNumber of times a B-tree page of the size PAGE_SIZE has been successfully compressed. This count should never exceed COMPRESS_OPS.
COMPRESS_TIMETotal time in seconds spent in attempts to compress B-tree pages of the size PAGE_SIZE.
UNCOMPRESS_OPSNumber of times a B-tree page of the size PAGE_SIZE has been uncompressed. B-tree pages are uncompressed whenever compression fails or at first access when the uncompressed page does not exist in the buffer pool.
UNCOMPRESS_TIMETotal time in seconds spent in uncompressing B-tree pages of the size PAGE_SIZE.

Notes:

20.29.2. The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables

The INNODB_CMPMEM and INNODB_CMPMEM_RESET tables contain status information on compressed pages within the InnoDB buffer pool.

Table 20.2. Columns of INNODB_CMPMEM and INNODB_CMPMEM_RESET

Column nameDescription
PAGE_SIZEBlock size in bytes. Each record of this table describes blocks of this size.
PAGES_USEDNumber of blocks of the size PAGE_SIZE that are currently in use.
PAGES_FREENumber of blocks of the size PAGE_SIZE that are currently available for allocation. This column shows the external fragmentation in the memory pool. Ideally, these numbers should be at most 1.
RELOCATION_OPSNumber of times a block of the size PAGE_SIZE has been relocated. The buddy system can relocate the allocated “buddy neighbor” of a freed block when it tries to form a bigger freed block. Reading from the table INNODB_CMPMEM_RESET resets this count.
RELOCATION_TIMETotal time in microseconds spent in relocating blocks of the size PAGE_SIZE. Reading from the table INNODB_CMPMEM_RESET resets this count.

Notes:

20.29.3. The INFORMATION_SCHEMA INNODB_TRX Table

The INNODB_TRX table contains information about every transaction currently executing inside InnoDB, including whether the transaction is waiting for a lock, when the transaction started, and the SQL statement the transaction is executing.

Table 20.3. INNODB_TRX Columns

Column nameDescription
TRX_IDUnique transaction ID number, internal to InnoDB.
TRX_WEIGHTThe weight of a transaction, reflecting (but not necessarily the exact count of) the number of rows altered and the number of rows locked by the transaction. To resolve a deadlock, InnoDB selects the transaction with the smallest weight as the “victim” to rollback. Transactions that have changed non-transactional tables are considered heavier than others, regardless of the number of altered and locked rows.
TRX_STATETransaction execution state. One of RUNNING, LOCK WAIT, ROLLING BACK or COMMITTING.
TRX_STARTEDTransaction start time.
TRX_REQUESTED_LOCK_IDID of the lock the transaction is currently waiting for (if TRX_STATE is LOCK WAIT, otherwise NULL). Details about the lock can be found by joining with INNODB_LOCKS on LOCK_ID.
TRX_WAIT_STARTEDTime when the transaction started waiting on the lock (if TRX_STATE is LOCK WAIT, otherwise NULL).
TRX_MYSQL_THREAD_IDMySQL thread ID. Can be used for joining with PROCESSLIST on ID. See Section 13.7.6.3.3, “Possible Inconsistency with PROCESSLIST.
TRX_QUERYThe SQL query that is being executed by the transaction.
TRX_OPERATION_STATEThe transaction's current operation, or NULL.
TRX_TABLES_IN_USEThe number of InnoDB tables used while processing the current SQL statement of this transaction.
TRX_TABLES_LOCKEDNumber of InnoDB tables that currently have any locks. (Because these are row locks, not table locks, the tables can usually still be read from and written to by multiple transactions, despite some rows being locked.)
TRX_LOCK_STRUCTSThe number of locks reserved by the transaction.
TRX_LOCK_MEMORY_BYTESTotal size taken up by the lock structures of this transaction in memory.
TRX_ROWS_LOCKEDApproximate number or rows locked by this transaction. The value might include delete-marked rows that are physically present but not visible to the transaction.
TRX_ROWS_MODIFIEDThe number of modified and inserted rows in this transaction.
TRX_CONCURRENCY_TICKETSA value indicating how much work the current transaction can do before being swapped out, as specified by the innodb_concurrency_tickets option.
TRX_ISOLATION_LEVELThe isolation level of the current transaction.
TRX_UNIQUE_CHECKSWhether unique checks are turned on or off for the current transaction. (They might be turned off during a bulk data load, for example.)
TRX_FOREIGN_KEY_CHECKSWhether foreign key checks are turned on or off for the current transaction. (They might be turned off during a bulk data load, for example.)
TRX_LAST_FOREIGN_KEY_ERRORDetailed error message for last FK error, or NULL.
TRX_ADAPTIVE_HASH_LATCHEDWhether or not the adaptive hash index is locked by the current transaction. (Only a single transaction at a time can modify the adaptive hash index.)
TRX_ADAPTIVE_HASH_TIMEOUTWhether to relinquish the search latch immediately for the adaptive hash index, or reserve it across calls from MySQL. When there is no AHI contention, this value remains zero and statements reserve the latch until they finish. During times of contention, it counts down to zero, and statements release the latch immediately after each row lookup.

Notes:

20.29.4. The INFORMATION_SCHEMA INNODB_LOCKS Table

The INNODB_LOCKS table contains information about each lock that an InnoDB transaction has requested but not yet acquired, and each lock that a transaction holds that is blocking another transaction.

Table 20.4. INNODB_LOCKS Columns

Column nameDescription
LOCK_IDUnique lock ID number, internal to InnoDB. Should be treated as an opaque string. Although LOCK_ID currently contains TRX_ID, the format of the data in LOCK_ID is not guaranteed to remain the same in future releases. You should not write programs that parse the LOCK_ID value.
LOCK_TRX_IDID of the transaction holding this lock. Details about the transaction can be found by joining with INNODB_TRX on TRX_ID.
LOCK_MODEMode of the lock. One of S, X, IS, IX, S_GAP, X_GAP, IS_GAP, IX_GAP, or AUTO_INC for shared, exclusive, intention shared, intention exclusive row locks, shared and exclusive gap locks, intention shared and intension exclusive gap locks, and auto-increment table level lock, respectively. Refer to the sections Section 13.6.9.1, “InnoDB Lock Modes” and Section 13.6.9, “The InnoDB Transaction Model and Locking” for information on InnoDB locking.
LOCK_TYPEType of the lock. One of RECORD or TABLE for record (row) level or table level locks, respectively.
LOCK_TABLEName of the table that has been locked or contains locked records.
LOCK_INDEXName of the index if LOCK_TYPE='RECORD', otherwise NULL.
LOCK_SPACETablespace ID of the locked record if LOCK_TYPE='RECORD', otherwise NULL.
LOCK_PAGEPage number of the locked record if LOCK_TYPE='RECORD', otherwise NULL.
LOCK_RECHeap number of the locked record within the page if LOCK_TYPE='RECORD', otherwise NULL.
LOCK_DATAPrimary key of the locked record if LOCK_TYPE='RECORD', otherwise NULL. This column contains the value(s) of the primary key column(s) in the locked row, formatted as a valid SQL string (ready to be copied to SQL commands). If there is no primary key then the InnoDB internal unique row ID number is used. When the page containing the locked record is not in the buffer pool (in the case that it was paged out to disk while the lock was held), InnoDB does not fetch the page from disk, to avoid unnecessary disk operations. Instead, LOCK_DATA is set to NULL.

Notes:

20.29.5. The INFORMATION_SCHEMA INNODB_LOCK_WAITS Table

The INNODB_LOCK_WAITS table contains one or more rows for each blocked InnoDB transaction, indicating the lock it has requested and any locks that are blocking that request.

Table 20.5. INNODB_LOCK_WAITS Columns

Column nameDescription
REQUESTING_TRX_IDID of the requesting transaction.
REQUESTED_LOCK_IDID of the lock for which a transaction is waiting. Details about the lock can be found by joining with INNODB_LOCKS on LOCK_ID.
BLOCKING_TRX_IDID of the blocking transaction.
BLOCKING_LOCK_IDID of a lock held by a transaction blocking another transaction from proceeding. Details about the lock can be found by joining with INNODB_LOCKS on LOCK_ID.

Notes:

20.30. Other INFORMATION_SCHEMA Tables

We intend to implement additional INFORMATION_SCHEMA tables.

20.31. Extensions to SHOW Statements

Some extensions to SHOW statements accompany the implementation of INFORMATION_SCHEMA:

  • SHOW can be used to get information about the structure of INFORMATION_SCHEMA itself.

  • Several SHOW statements accept a WHERE clause that provides more flexibility in specifying which rows to display.

INFORMATION_SCHEMA is an information database, so its name is included in the output from SHOW DATABASES. Similarly, SHOW TABLES can be used with INFORMATION_SCHEMA to obtain a list of its tables:

mysql> SHOW TABLES FROM INFORMATION_SCHEMA;
+---------------------------------------+
| Tables_in_INFORMATION_SCHEMA          |
+---------------------------------------+
| CHARACTER_SETS                        |
| COLLATIONS                            |
| COLLATION_CHARACTER_SET_APPLICABILITY |
| COLUMNS                               |
| COLUMN_PRIVILEGES                     |
| ENGINES                               |
| EVENTS                                |
| FILES                                 |
| GLOBAL_STATUS                         |
| GLOBAL_VARIABLES                      |
| KEY_COLUMN_USAGE                      |
| PARTITIONS                            |
| PLUGINS                               |
| PROCESSLIST                           |
| REFERENTIAL_CONSTRAINTS               |
| ROUTINES                              |
| SCHEMATA                              |
| SCHEMA_PRIVILEGES                     |
| SESSION_STATUS                        |
| SESSION_VARIABLES                     |
| STATISTICS                            |
| TABLES                                |
| TABLE_CONSTRAINTS                     |
| TABLE_PRIVILEGES                      |
| TRIGGERS                              |
| USER_PRIVILEGES                       |
| VIEWS                                 |
+---------------------------------------+
27 rows in set (0.00 sec)

SHOW COLUMNS and DESCRIBE can display information about the columns in individual INFORMATION_SCHEMA tables.

SHOW statements that accept a LIKE clause to limit the rows displayed also permit a WHERE clause that specifies more general conditions that selected rows must satisfy:

SHOW CHARACTER SET
SHOW COLLATION
SHOW COLUMNS
SHOW DATABASES
SHOW FUNCTION STATUS
SHOW INDEX
SHOW OPEN TABLES
SHOW PROCEDURE STATUS
SHOW STATUS
SHOW TABLE STATUS
SHOW TABLES
SHOW TRIGGERS
SHOW VARIABLES

The WHERE clause, if present, is evaluated against the column names displayed by the SHOW statement. For example, the SHOW CHARACTER SET statement produces these output columns:

mysql> SHOW CHARACTER SET;
+----------+-----------------------------+---------------------+--------+
| Charset  | Description                 | Default collation   | Maxlen |
+----------+-----------------------------+---------------------+--------+
| big5     | Big5 Traditional Chinese    | big5_chinese_ci     |      2 |
| dec8     | DEC West European           | dec8_swedish_ci     |      1 |
| cp850    | DOS West European           | cp850_general_ci    |      1 |
| hp8      | HP West European            | hp8_english_ci      |      1 |
| koi8r    | KOI8-R Relcom Russian       | koi8r_general_ci    |      1 |
| latin1   | cp1252 West European        | latin1_swedish_ci   |      1 |
| latin2   | ISO 8859-2 Central European | latin2_general_ci   |      1 |
...

To use a WHERE clause with SHOW CHARACTER SET, you would refer to those column names. As an example, the following statement displays information about character sets for which the default collation contains the string 'japanese':

mysql> SHOW CHARACTER SET WHERE `Default collation` LIKE '%japanese%';
+---------+---------------------------+---------------------+--------+
| Charset | Description               | Default collation   | Maxlen |
+---------+---------------------------+---------------------+--------+
| ujis    | EUC-JP Japanese           | ujis_japanese_ci    |      3 |
| sjis    | Shift-JIS Japanese        | sjis_japanese_ci    |      2 |
| cp932   | SJIS for Windows Japanese | cp932_japanese_ci   |      2 |
| eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci |      3 |
+---------+---------------------------+---------------------+--------+

This statement displays the multi-byte character sets:

mysql> SHOW CHARACTER SET WHERE Maxlen > 1;
+---------+---------------------------+---------------------+--------+
| Charset | Description               | Default collation   | Maxlen |
+---------+---------------------------+---------------------+--------+
| big5    | Big5 Traditional Chinese  | big5_chinese_ci     |      2 |
| ujis    | EUC-JP Japanese           | ujis_japanese_ci    |      3 |
| sjis    | Shift-JIS Japanese        | sjis_japanese_ci    |      2 |
| euckr   | EUC-KR Korean             | euckr_korean_ci     |      2 |
| gb2312  | GB2312 Simplified Chinese | gb2312_chinese_ci   |      2 |
| gbk     | GBK Simplified Chinese    | gbk_chinese_ci      |      2 |
| utf8    | UTF-8 Unicode             | utf8_general_ci     |      3 |
| ucs2    | UCS-2 Unicode             | ucs2_general_ci     |      2 |
| cp932   | SJIS for Windows Japanese | cp932_japanese_ci   |      2 |
| eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci |      3 |
+---------+---------------------------+---------------------+--------+