Information Schema
As part of MySQL compatibility, TiDB supports a number of INFORMATION_SCHEMA tables. Many of these tables also have a corresponding SHOW command. The benefit of querying INFORMATION_SCHEMA is that it is possible to join between tables.
Fully Supported Information Schema Tables
ANALYZE_STATUS table
The ANALYZE_STATUS table provides information about the running tasks that collect statistics and a limited number of history tasks.
select * from `ANALYZE_STATUS`;
+--------------+------------+----------------+-------------------+----------------+---------------------+----------+
| TABLE_SCHEMA | TABLE_NAME | PARTITION_NAME | JOB_INFO | PROCESSED_ROWS | START_TIME | STATE |
+--------------+------------+----------------+-------------------+----------------+---------------------+----------+
| test | t | | analyze index idx | 2 | 2019-06-21 19:51:14 | finished |
| test | t | | analyze columns | 2 | 2019-06-21 19:51:14 | finished |
| test | t1 | p0 | analyze columns | 0 | 2019-06-21 19:51:15 | finished |
| test | t1 | p3 | analyze columns | 0 | 2019-06-21 19:51:15 | finished |
| test | t1 | p1 | analyze columns | 0 | 2019-06-21 19:51:15 | finished |
| test | t1 | p2 | analyze columns | 1 | 2019-06-21 19:51:15 | finished |
+--------------+------------+----------------+-------------------+----------------+---------------------+----------+
6 rows in set
CHARACTER_SETS table
The CHARACTER_SETS table provides information about character sets. Currently, TiDB only supports some of the character sets.
SELECT * FROM character_sets;
+--------------------+----------------------+---------------+--------+
| CHARACTER_SET_NAME | DEFAULT_COLLATE_NAME | DESCRIPTION | MAXLEN |
+--------------------+----------------------+---------------+--------+
| utf8 | utf8_bin | UTF-8 Unicode | 3 |
| utf8mb4 | utf8mb4_bin | UTF-8 Unicode | 4 |
| ascii | ascii_bin | US ASCII | 1 |
| latin1 | latin1_bin | Latin1 | 1 |
| binary | binary | binary | 1 |
+--------------------+----------------------+---------------+--------+
5 rows in set (0.00 sec)
COLLATIONS table
The COLLATIONS table provides a list of collations that correspond to character sets in the CHARACTER_SETS table. Currently this table is included only for compatibility with MySQL, as TiDB only supports binary collation:
SELECT * FROM collations WHERE character_set_name='utf8mb4';
+------------------------+--------------------+------+------------+-------------+---------+
| COLLATION_NAME | CHARACTER_SET_NAME | ID | IS_DEFAULT | IS_COMPILED | SORTLEN |
+------------------------+--------------------+------+------------+-------------+---------+
| utf8mb4_general_ci | utf8mb4 | 45 | Yes | Yes | 1 |
| utf8mb4_bin | utf8mb4 | 46 | | Yes | 1 |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 1 |
| utf8mb4_icelandic_ci | utf8mb4 | 225 | | Yes | 1 |
| utf8mb4_latvian_ci | utf8mb4 | 226 | | Yes | 1 |
| utf8mb4_romanian_ci | utf8mb4 | 227 | | Yes | 1 |
| utf8mb4_slovenian_ci | utf8mb4 | 228 | | Yes | 1 |
| utf8mb4_polish_ci | utf8mb4 | 229 | | Yes | 1 |
| utf8mb4_estonian_ci | utf8mb4 | 230 | | Yes | 1 |
| utf8mb4_spanish_ci | utf8mb4 | 231 | | Yes | 1 |
| utf8mb4_swedish_ci | utf8mb4 | 232 | | Yes | 1 |
| utf8mb4_turkish_ci | utf8mb4 | 233 | | Yes | 1 |
| utf8mb4_czech_ci | utf8mb4 | 234 | | Yes | 1 |
| utf8mb4_danish_ci | utf8mb4 | 235 | | Yes | 1 |
| utf8mb4_lithuanian_ci | utf8mb4 | 236 | | Yes | 1 |
| utf8mb4_slovak_ci | utf8mb4 | 237 | | Yes | 1 |
| utf8mb4_spanish2_ci | utf8mb4 | 238 | | Yes | 1 |
| utf8mb4_roman_ci | utf8mb4 | 239 | | Yes | 1 |
| utf8mb4_persian_ci | utf8mb4 | 240 | | Yes | 1 |
| utf8mb4_esperanto_ci | utf8mb4 | 241 | | Yes | 1 |
| utf8mb4_hungarian_ci | utf8mb4 | 242 | | Yes | 1 |
| utf8mb4_sinhala_ci | utf8mb4 | 243 | | Yes | 1 |
| utf8mb4_german2_ci | utf8mb4 | 244 | | Yes | 1 |
| utf8mb4_croatian_ci | utf8mb4 | 245 | | Yes | 1 |
| utf8mb4_unicode_520_ci | utf8mb4 | 246 | | Yes | 1 |
| utf8mb4_vietnamese_ci | utf8mb4 | 247 | | Yes | 1 |
+------------------------+--------------------+------+------------+-------------+---------+
26 rows in set (0.00 sec)
COLLATION_CHARACTER_SET_APPLICABILITY table
The COLLATION_CHARACTER_SET_APPLICABILITY table maps collations to the applicable character set name. Similar to the COLLATIONS table, it is included only for compatibility with MySQL:
SELECT * FROM collation_character_set_applicability WHERE character_set_name='utf8mb4';
+------------------------+--------------------+
| COLLATION_NAME | CHARACTER_SET_NAME |
+------------------------+--------------------+
| utf8mb4_general_ci | utf8mb4 |
| utf8mb4_bin | utf8mb4 |
| utf8mb4_unicode_ci | utf8mb4 |
| utf8mb4_icelandic_ci | utf8mb4 |
| utf8mb4_latvian_ci | utf8mb4 |
| utf8mb4_romanian_ci | utf8mb4 |
| utf8mb4_slovenian_ci | utf8mb4 |
| utf8mb4_polish_ci | utf8mb4 |
| utf8mb4_estonian_ci | utf8mb4 |
| utf8mb4_spanish_ci | utf8mb4 |
| utf8mb4_swedish_ci | utf8mb4 |
| utf8mb4_turkish_ci | utf8mb4 |
| utf8mb4_czech_ci | utf8mb4 |
| utf8mb4_danish_ci | utf8mb4 |
| utf8mb4_lithuanian_ci | utf8mb4 |
| utf8mb4_slovak_ci | utf8mb4 |
| utf8mb4_spanish2_ci | utf8mb4 |
| utf8mb4_roman_ci | utf8mb4 |
| utf8mb4_persian_ci | utf8mb4 |
| utf8mb4_esperanto_ci | utf8mb4 |
| utf8mb4_hungarian_ci | utf8mb4 |
| utf8mb4_sinhala_ci | utf8mb4 |
| utf8mb4_german2_ci | utf8mb4 |
| utf8mb4_croatian_ci | utf8mb4 |
| utf8mb4_unicode_520_ci | utf8mb4 |
| utf8mb4_vietnamese_ci | utf8mb4 |
+------------------------+--------------------+
26 rows in set (0.00 sec)
COLUMNS table
The COLUMNS table provides detailed information about columns in tables:
CREATE TABLE test.t1 (a int);
1 row in set (0.01 sec)
SELECT * FROM information_schema.columns WHERE table_schema='test' AND TABLE_NAME='t1';
*************************** 1. row ***************************
TABLE_CATALOG: def
TABLE_SCHEMA: test
TABLE_NAME: t1
COLUMN_NAME: a
ORDINAL_POSITION: 1
COLUMN_DEFAULT: NULL
IS_NULLABLE: YES
DATA_TYPE: int
CHARACTER_MAXIMUM_LENGTH: NULL
CHARACTER_OCTET_LENGTH: NULL
NUMERIC_PRECISION: 11
NUMERIC_SCALE: 0
DATETIME_PRECISION: NULL
CHARACTER_SET_NAME: NULL
COLLATION_NAME: NULL
COLUMN_TYPE: int(11)
COLUMN_KEY:
EXTRA:
PRIVILEGES: select,insert,update,references
COLUMN_COMMENT:
GENERATION_EXPRESSION:
1 row in set (0.01 sec)
The description of columns in the COLUMNS table is as follows:
TABLE_CATALOG: The name of the catalog to which the table with the column belongs. The value is alwaysdef.TABLE_SCHEMA: The name of the schema in which the table with the column is located.TABLE_NAME: The name of the table with the column.COLUMN_NAME: The name of the column.ORDINAL_POSITION: The position of the column in the table.COLUMN_DEFAULT: The default value of the column. If the explicit default value isNULL, or if the column definition does not include thedefaultclause, this value isNULL.IS_NULLABLE: Whether the column is nullable. If the column can store null values, this value isYES; otherwise, it isNO.DATA_TYPE: The type of data in the column.CHARACTER_MAXIMUM_LENGTH: For string columns, the maximum length in characters.CHARACTER_OCTET_LENGTH: For string columns, the maximum length in bytes.NUMERIC_PRECISION: The numeric precision of a number-type column.NUMERIC_SCALE: The numeric scale of a number-type column.DATETIME_PRECISION: For time-type columns, the fractional seconds precision.CHARACTER_SET_NAME: The name of the character set of a string column.COLLATION_NAME: The name of the collation of a string column.COLUMN_TYPE: The column type.COLUMN_KEY: Whether this column is indexed. This field might have the following values:- Empty: This column is not indexed, or this column is indexed and is the second column in a multi-column non-unique index.
PRI: This column is the primary key or one of multiple primary keys.UNI: This column is the first column of the unique index.MUL: The column is the first column of a non-unique index, in which a given value is allowed to occur for multiple times.
EXTRA: Any additional information of the given column.PRIVILEGES: The privilege that the current user has on this column. Currently, this value is fixed in TiDB, and is alwaysselect,insert,update,references.COLUMN_COMMENT: Comments contained in the column definition.GENERATION_EXPRESSION: For generated columns, this value displays the expression used to calculate the column value. For non-generated columns, the value is empty.
The corresponding SHOW statement is as follows:
SHOW COLUMNS FROM t1 FROM test;
+-------+---------+------+------+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+---------+------+------+---------+-------+
| a | int(11) | YES | | NULL | |
+-------+---------+------+------+---------+-------+
1 row in set (0.00 sec)
ENGINES table
The ENGINES table provides information about storage engines. For compatibility, TiDB will always describe InnoDB as the only supported engine. In addition, other column values in the ENGINES table are also fixed values.
SELECT * FROM engines;
*************************** 1. row ***************************
ENGINE: InnoDB
SUPPORT: DEFAULT
COMMENT: Supports transactions, row-level locking, and foreign keys
TRANSACTIONS: YES
XA: YES
SAVEPOINTS: YES
1 row in set (0.00 sec)
The description of columns in the ENGINES table is as follows:
ENGINES: The name of the storage engine.SUPPORT: The level of support that the server has on the storage engine. In TiDB, the value is alwaysDEFAULT.COMMENT: The brief comment on the storage engine.TRANSACTIONS：Whether the storage engine supports transactions.XA: Whether the storage engine supports XA transactions.SAVEPOINTS: Whether the storage engine supportssavepoints.
KEY_COLUMN_USAGE table
The KEY_COLUMN_USAGE table describes the key constraints of the columns, such as the primary key constraint:
SELECT * FROM key_column_usage WHERE table_schema='mysql' and table_name='user';
*************************** 1. row ***************************
CONSTRAINT_CATALOG: def
CONSTRAINT_SCHEMA: mysql
CONSTRAINT_NAME: PRIMARY
TABLE_CATALOG: def
TABLE_SCHEMA: mysql
TABLE_NAME: user
COLUMN_NAME: Host
ORDINAL_POSITION: 1
POSITION_IN_UNIQUE_CONSTRAINT: NULL
REFERENCED_TABLE_SCHEMA: NULL
REFERENCED_TABLE_NAME: NULL
REFERENCED_COLUMN_NAME: NULL
*************************** 2. row ***************************
CONSTRAINT_CATALOG: def
CONSTRAINT_SCHEMA: mysql
CONSTRAINT_NAME: PRIMARY
TABLE_CATALOG: def
TABLE_SCHEMA: mysql
TABLE_NAME: user
COLUMN_NAME: User
ORDINAL_POSITION: 2
POSITION_IN_UNIQUE_CONSTRAINT: NULL
REFERENCED_TABLE_SCHEMA: NULL
REFERENCED_TABLE_NAME: NULL
REFERENCED_COLUMN_NAME: NULL
2 rows in set (0.00 sec)
The description of columns in the KEY_COLUMN_USAGE table is as follows:
CONSTRAINT_CATALOG: The name of the catalog to which the constraint belongs. The value is alwaysdef.CONSTRAINT_SCHEMA: The name of the schema to which the constraint belongs.CONSTRAINT_NAME: The name of the constraint.TABLE_CATALOG: The name of the catalog to which the table belongs. The value is alwaysdef.TABLE_SCHEMA: The name of the schema to which the table belongs.TABLE_NAME: The name of the table with constraints.COLUMN_NAME: The name of the column with constraints.ORDINAL_POSITION: The position of the column in the constraint, rather than in the table. The position number starts from1.POSITION_IN_UNIQUE_CONSTRAINT: The unique constraint and the primary key constraint are empty. For foreign key constraints, this column is the position of the referenced table's key.REFERENCED_TABLE_SCHEMA: The name of the schema referenced by the constraint. Currently in TiDB, the value of this column in all constraints isnil, except for the foreign key constraint.REFERENCED_TABLE_NAME: The name of the table referenced by the constraint. Currently in TiDB, the value of this column in all constraints isnil, except for the foreign key constraint.REFERENCED_COLUMN_NAME: The name of the column referenced by the constraint. Currently in TiDB, the value of this column in all constraints isnil, except for the foreign key constraint.
PROCESSLIST table
PROCESSLIST, just like show processlist, is used to view the requests that are being handled.
The PROCESSLIST table has a MEM column New in v3.0.5 that show processlist does not have. MEM means the occupied memory of the requests being handled, and its unit is byte.
+----+------+------+--------------------+---------+------+-------+---------------------------+-----+
| ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO | MEM |
+----+------+------+--------------------+---------+------+-------+---------------------------+-----+
| 1 | root | ::1 | INFORMATION_SCHEMA | Query | 0 | 2 | select * from PROCESSLIST | 0 |
+----+------+------+--------------------+---------+------+-------+---------------------------+-----+
SCHEMATA table
The SCHEMATA table provides information about databases. The table data is equivalent to the result of the SHOW DATABASES statement:
select * from SCHEMATA;
*************************** 1. row ***************************
CATALOG_NAME: def
SCHEMA_NAME: INFORMATION_SCHEMA
DEFAULT_CHARACTER_SET_NAME: utf8mb4
DEFAULT_COLLATION_NAME: utf8mb4_bin
SQL_PATH: NULL
*************************** 2. row ***************************
CATALOG_NAME: def
SCHEMA_NAME: mysql
DEFAULT_CHARACTER_SET_NAME: utf8mb4
DEFAULT_COLLATION_NAME: utf8mb4_bin
SQL_PATH: NULL
*************************** 3. row ***************************
CATALOG_NAME: def
SCHEMA_NAME: PERFORMANCE_SCHEMA
DEFAULT_CHARACTER_SET_NAME: utf8mb4
DEFAULT_COLLATION_NAME: utf8mb4_bin
SQL_PATH: NULL
*************************** 4. row ***************************
CATALOG_NAME: def
SCHEMA_NAME: test
DEFAULT_CHARACTER_SET_NAME: utf8mb4
DEFAULT_COLLATION_NAME: utf8mb4_bin
SQL_PATH: NULL
4 rows in set (0.00 sec)
SESSION_VARIABLES table
The SESSION_VARIABLES table provides information about session variables. The table data is similar to the result of the SHOW SESSION VARIABLES statement:
SELECT * FROM session_variables LIMIT 10;
+----------------------------------+----------------------+
| VARIABLE_NAME | VARIABLE_VALUE |
+----------------------------------+----------------------+
| max_write_lock_count | 18446744073709551615 |
| server_id_bits | 32 |
| net_read_timeout | 30 |
| innodb_online_alter_log_max_size | 134217728 |
| innodb_optimize_fulltext_only | OFF |
| max_join_size | 18446744073709551615 |
| innodb_read_io_threads | 4 |
| session_track_gtids | OFF |
| have_ssl | DISABLED |
| max_binlog_cache_size | 18446744073709547520 |
+----------------------------------+----------------------+
10 rows in set (0.00 sec)
SLOW_QUERY table
The SLOW_QUERY table provides the slow query information, which is the parsing result of the TiDB slow log file. The column names in the table are corresponding to the field names in the slow log. For how to use this table to identify problematic statements and improve query performance of the SQL engine, see Slow Query Log Document.
mysql> desc information_schema.slow_query;
+---------------+---------------------+------+------+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------+---------------------+------+------+---------+-------+
| Time | timestamp unsigned | YES | | NULL | |
| Txn_start_ts | bigint(20) unsigned | YES | | NULL | |
| User | varchar(64) | YES | | NULL | |
| Host | varchar(64) | YES | | NULL | |
| Conn_ID | bigint(20) unsigned | YES | | NULL | |
| Query_time | double unsigned | YES | | NULL | |
| Process_time | double unsigned | YES | | NULL | |
| Wait_time | double unsigned | YES | | NULL | |
| Backoff_time | double unsigned | YES | | NULL | |
| Request_count | bigint(20) unsigned | YES | | NULL | |
| Total_keys | bigint(20) unsigned | YES | | NULL | |
| Process_keys | bigint(20) unsigned | YES | | NULL | |
| DB | varchar(64) | YES | | NULL | |
| Index_ids | varchar(100) | YES | | NULL | |
| Is_internal | tinyint(1) unsigned | YES | | NULL | |
| Digest | varchar(64) | YES | | NULL | |
| Stats | varchar(512) | YES | | NULL | |
| Cop_proc_avg | double unsigned | YES | | NULL | |
| Cop_proc_p90 | double unsigned | YES | | NULL | |
| Cop_proc_max | double unsigned | YES | | NULL | |
| Cop_proc_addr | varchar(64) | YES | | NULL | |
| Cop_wait_avg | double unsigned | YES | | NULL | |
| Cop_wait_p90 | double unsigned | YES | | NULL | |
| Cop_wait_max | double unsigned | YES | | NULL | |
| Cop_wait_addr | varchar(64) | YES | | NULL | |
| Mem_max | bigint(20) unsigned | YES | | NULL | |
| Succ | tinyint(1) unsigned | YES | | NULL | |
| Query | longblob unsigned | YES | | NULL | |
+---------------+---------------------+------+------+---------+-------+
STATISTICS table
The STATISTICS table provides information about table indexes:
desc statistics;
+---------------|---------------------|------|------|---------|-------+
| Field | Type | Null | Key | Default | Extra |
+---------------|---------------------|------|------|---------|-------+
| TABLE_CATALOG | varchar(512) | YES | | NULL | |
| TABLE_SCHEMA | varchar(64) | YES | | NULL | |
| TABLE_NAME | varchar(64) | YES | | NULL | |
| NON_UNIQUE | varchar(1) | YES | | NULL | |
| INDEX_SCHEMA | varchar(64) | YES | | NULL | |
| INDEX_NAME | varchar(64) | YES | | NULL | |
| SEQ_IN_INDEX | bigint(2) UNSIGNED | YES | | NULL | |
| COLUMN_NAME | varchar(21) | YES | | NULL | |
| COLLATION | varchar(1) | YES | | NULL | |
| CARDINALITY | bigint(21) UNSIGNED | YES | | NULL | |
| SUB_PART | bigint(3) UNSIGNED | YES | | NULL | |
| PACKED | varchar(10) | YES | | NULL | |
| NULLABLE | varchar(3) | YES | | NULL | |
| INDEX_TYPE | varchar(16) | YES | | NULL | |
| COMMENT | varchar(16) | YES | | NULL | |
| INDEX_COMMENT | varchar(1024) | YES | | NULL | |
+---------------|---------------------|------|------|---------|-------+
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
TABLES table
The TABLES table provides information about tables in databases:
SELECT * FROM tables WHERE table_schema='mysql' AND table_name='user';
*************************** 1. row ***************************
TABLE_CATALOG: def
TABLE_SCHEMA: mysql
TABLE_NAME: user
TABLE_TYPE: BASE TABLE
ENGINE: InnoDB
VERSION: 10
ROW_FORMAT: Compact
TABLE_ROWS: 0
AVG_ROW_LENGTH: 0
DATA_LENGTH: 0
MAX_DATA_LENGTH: 0
INDEX_LENGTH: 0
DATA_FREE: 0
AUTO_INCREMENT: 0
CREATE_TIME: 2019-03-29 09:17:27
UPDATE_TIME: NULL
CHECK_TIME: NULL
TABLE_COLLATION: utf8mb4_bin
CHECKSUM: NULL
CREATE_OPTIONS:
TABLE_COMMENT:
TIDB_TABLE_ID: 5
1 row in set (0.00 sec)
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']
TABLE_CONSTRAINTS table
The TABLE_CONSTRAINTS table describes which tables have constraints:
SELECT * FROM table_constraints WHERE constraint_type='UNIQUE';
*************************** 1. row ***************************
CONSTRAINT_CATALOG: def
CONSTRAINT_SCHEMA: mysql
CONSTRAINT_NAME: name
TABLE_SCHEMA: mysql
TABLE_NAME: help_topic
CONSTRAINT_TYPE: UNIQUE
*************************** 2. row ***************************
CONSTRAINT_CATALOG: def
CONSTRAINT_SCHEMA: mysql
CONSTRAINT_NAME: tbl
TABLE_SCHEMA: mysql
TABLE_NAME: stats_meta
CONSTRAINT_TYPE: UNIQUE
*************************** 3. row ***************************
CONSTRAINT_CATALOG: def
CONSTRAINT_SCHEMA: mysql
CONSTRAINT_NAME: tbl
TABLE_SCHEMA: mysql
TABLE_NAME: stats_histograms
CONSTRAINT_TYPE: UNIQUE
*************************** 4. row ***************************
CONSTRAINT_CATALOG: def
CONSTRAINT_SCHEMA: mysql
CONSTRAINT_NAME: tbl
TABLE_SCHEMA: mysql
TABLE_NAME: stats_buckets
CONSTRAINT_TYPE: UNIQUE
*************************** 5. row ***************************
CONSTRAINT_CATALOG: def
CONSTRAINT_SCHEMA: mysql
CONSTRAINT_NAME: delete_range_index
TABLE_SCHEMA: mysql
TABLE_NAME: gc_delete_range
CONSTRAINT_TYPE: UNIQUE
*************************** 6. row ***************************
CONSTRAINT_CATALOG: def
CONSTRAINT_SCHEMA: mysql
CONSTRAINT_NAME: delete_range_done_index
TABLE_SCHEMA: mysql
TABLE_NAME: gc_delete_range_done
CONSTRAINT_TYPE: UNIQUE
6 rows in set (0.00 sec)
- The
CONSTRAINT_TYPEvalue can beUNIQUE,PRIMARY KEY, orFOREIGN KEY. - The
UNIQUEandPRIMARY KEYinformation is similar to the result of theSHOW INDEXstatement.
TIDB_HOT_REGIONS table
The TIDB_HOT_REGIONS table provides information about hot spot Regions.
desc TIDB_HOT_REGIONS;
+----------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------------+---------------------+------+-----+---------+-------+
| TABLE_ID | bigint(21) unsigned | YES | | <null> | |
| INDEX_ID | bigint(21) unsigned | YES | | <null> | |
| DB_NAME | varchar(64) | YES | | <null> | |
| TABLE_NAME | varchar(64) | YES | | <null> | |
| INDEX_NAME | varchar(64) | YES | | <null> | |
| TYPE | varchar(64) | YES | | <null> | |
| MAX_HOT_DEGREE | bigint(21) unsigned | YES | | <null> | |
| REGION_COUNT | bigint(21) unsigned | YES | | <null> | |
| FLOW_BYTES | bigint(21) unsigned | YES | | <null> | |
+----------------+---------------------+------+-----+---------+-------+
TIDB_INDEXES table
The TIDB_INDEXES table provides the INDEX information of all tables.
desc TIDB_INDEXES;
+---------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------+---------------------+------+-----+---------+-------+
| TABLE_SCHEMA | varchar(64) | YES | | <null> | |
| TABLE_NAME | varchar(64) | YES | | <null> | |
| NON_UNIQUE | bigint(21) unsigned | YES | | <null> | |
| KEY_NAME | varchar(64) | YES | | <null> | |
| SEQ_IN_INDEX | bigint(21) unsigned | YES | | <null> | |
| COLUMN_NAME | varchar(64) | YES | | <null> | |
| SUB_PART | bigint(21) unsigned | YES | | <null> | |
| INDEX_COMMENT | varchar(2048) | YES | | <null> | |
| INDEX_ID | bigint(21) unsigned | YES | | <null> | |
+---------------+---------------------+------+-----+---------+-------+
Fields in the TIDB_INDEXES table are described as follows:
TABLE_SCHEMA: The name of the schema to which the index belongs.TABLE_NAME: The name of the table to which the index belongs.NON_UNIQUE: If the index is unique, the value is0; otherwise, the value is1.KEY_NAME: The index name. If the index is the primary key, the name isPRIMARY.SEQ_IN_INDEX: The sequential number of columns in the index, which starts from1.COLUMN_NAME: The name of the column where the index is located.SUB_PART: The prefix length of the index. If the the column is partly indexed, theSUB_PARTvalue is the count of the indexed characters; otherwise, the value isNULL.INDEX_COMMENT: The comment of the index, which is made when the index is created.INDEX_ID: The index ID.
TIKV_REGION_PEERS table
The TIKV_REGION_PEERS table provides the peer information of all Regions.
desc TIKV_REGION_PEERS;
+--------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+--------------+---------------------+------+-----+---------+-------+
| REGION_ID | bigint(21) unsigned | YES | | <null> | |
| PEER_ID | bigint(21) unsigned | YES | | <null> | |
| STORE_ID | bigint(21) unsigned | YES | | <null> | |
| IS_LEARNER | tinyint(1) unsigned | YES | | <null> | |
| IS_LEADER | tinyint(1) unsigned | YES | | <null> | |
| STATUS | varchar(10) | YES | | <null> | |
| DOWN_SECONDS | bigint(21) unsigned | YES | | <null> | |
+--------------+---------------------+------+-----+---------+-------+
TIKV_REGION_STATUS table
The TIKV_REGION_STATUS table provides the status information of all Regions.
desc TIKV_REGION_STATUS;
+------------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------------+---------------------+------+-----+---------+-------+
| REGION_ID | bigint(21) unsigned | YES | | <null> | |
| START_KEY | text | YES | | <null> | |
| END_KEY | text | YES | | <null> | |
| EPOCH_CONF_VER | bigint(21) unsigned | YES | | <null> | |
| EPOCH_VERSION | bigint(21) unsigned | YES | | <null> | |
| WRITTEN_BYTES | bigint(21) unsigned | YES | | <null> | |
| READ_BYTES | bigint(21) unsigned | YES | | <null> | |
| APPROXIMATE_SIZE | bigint(21) unsigned | YES | | <null> | |
| APPROXIMATE_KEYS | bigint(21) unsigned | YES | | <null> | |
+------------------+---------------------+------+-----+---------+-------+
TIKV_STORE_STATUS table
The TIKV_STORE_STATUS table provides the status information of all TiKV Stores.
desc TIKV_STORE_STATUS;
+-------------------+---------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------------+---------------------+------+-----+---------+-------+
| STORE_ID | bigint(21) unsigned | YES | | <null> | |
| ADDRESS | varchar(64) | YES | | <null> | |
| STORE_STATE | bigint(21) unsigned | YES | | <null> | |
| STORE_STATE_NAME | varchar(64) | YES | | <null> | |
| LABEL | json unsigned | YES | | <null> | |
| VERSION | varchar(64) | YES | | <null> | |
| CAPACITY | varchar(64) | YES | | <null> | |
| AVAILABLE | varchar(64) | YES | | <null> | |
| LEADER_COUNT | bigint(21) unsigned | YES | | <null> | |
| LEADER_WEIGHT | bigint(21) unsigned | YES | | <null> | |
| LEADER_SCORE | bigint(21) unsigned | YES | | <null> | |
| LEADER_SIZE | bigint(21) unsigned | YES | | <null> | |
| REGION_COUNT | bigint(21) unsigned | YES | | <null> | |
| REGION_WEIGHT | bigint(21) unsigned | YES | | <null> | |
| REGION_SCORE | bigint(21) unsigned | YES | | <null> | |
| REGION_SIZE | bigint(21) unsigned | YES | | <null> | |
| START_TS | datetime unsigned | YES | | <null> | |
| LAST_HEARTBEAT_TS | datetime unsigned | YES | | <null> | |
| UPTIME | varchar(64) | YES | | <null> | |
+-------------------+---------------------+------+-----+---------+-------+
USER_PRIVILEGES table
The USER_PRIVILEGES table provides information about global privileges. This information comes from the mysql.user system table:
desc USER_PRIVILEGES;
+----------------|--------------|------|------|---------|-------+
| Field | Type | Null | Key | Default | Extra |
+----------------|--------------|------|------|---------|-------+
| GRANTEE | varchar(81) | YES | | NULL | |
| TABLE_CATALOG | varchar(512) | YES | | NULL | |
| PRIVILEGE_TYPE | varchar(64) | YES | | NULL | |
| IS_GRANTABLE | varchar(3) | YES | | NULL | |
+----------------|--------------|------|------|---------|-------+
4 rows in set (0.00 sec)
Fields in the USER_PRIVILEGES table are described as follows:
GRANTEE: The name of the granted user, which is in the format of'user_name'@'host_name'.TABLE_CATALOG: The name of the catalog to which the table belongs. This value is alwaysdef.PRIVILEGE_TYPE: The privilege type to be granted. Only one privilege type is shown in each row.IS_GRANTABLE: If you have theGRANT OPTIONprivilege, the value isYES; otherwise, the value isNO.
VIEWS table
The VIEWS table provides information about SQL views:
create view test.v1 as select 1;
Query OK, 0 rows affected (0.00 sec)
select * from views;
*************************** 1. row ***************************
TABLE_CATALOG: def
TABLE_SCHEMA: test
TABLE_NAME: v1
VIEW_DEFINITION: select 1
CHECK_OPTION: CASCADED
IS_UPDATABLE: NO
DEFINER: root@127.0.0.1
SECURITY_TYPE: DEFINER
CHARACTER_SET_CLIENT: utf8
COLLATION_CONNECTION: utf8_general_ci
1 row in set (0.00 sec)
Fields in the VIEWS table are described as follows:
TABLE_CATALOG: The name of the catalog to which the view belongs. This value is alwaysdef.TABLE_SCHEMA: The name of the schema to which the view belongs.TABLE_NAME: The view name.VIEW_DEFINITION: The definition of view, which is made by theSELECTstatement when the view is created.CHECK_OPTION: TheCHECK_OPTIONvalue. The value options areNONE,CASCADE, andLOCAL.IS_UPDATABLE: WhetherUPDATE/INSERT/DELETEis applicable to the view. In TiDB, the value is alwaysNO.DEFINER: The name of the user who creates the view, which is in the format of'user_name'@'host_name'.SECURITY_TYPE: The value ofSQL SECURITY. The value options areDEFINERandINVOKER.CHARACTER_SET_CLIENT: The value of thecharacter_set_clientsession variable when the view is created.COLLATION_CONNECTION: The value of thecollation_connectionsession variable when the view is created.
TIDB_INDEXES table
The TIDB_INDEXES table provides index-related information.
desc tidb_indexes\G
*************************** 1. row ***************************
Table: TIDB_INDEXES
Create Table: CREATE TABLE `TIDB_INDEXES` (
`TABLE_SCHEMA` varchar(64) DEFAULT NULL,
`TABLE_NAME` varchar(64) DEFAULT NULL,
`NON_UNIQUE` bigint(21) unsigned DEFAULT NULL,
`KEY_NAME` varchar(64) DEFAULT NULL,
`SEQ_IN_INDEX` bigint(21) unsigned DEFAULT NULL,
`COLUMN_NAME` varchar(64) DEFAULT NULL,
`SUB_PART` bigint(21) unsigned DEFAULT NULL,
`INDEX_COMMENT` varchar(2048) DEFAULT NULL,
`INDEX_ID` bigint(21) unsigned DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
1 row in set (0.00 sec)
INDEX_ID is the unique ID that TiDB allocates for each index. It can be used to do a join operation with INDEX_ID obtained from another table or API.
For example, you can obtain TABLE_ID and INDEX_ID that are involved in some slow query in the SLOW_QUERY table and then obtain the specific index information using the following SQL statements:
select
tidb_indexes.*
from
tidb_indexes,
tables
where
tidb_indexes.table_schema = tables.table_schema
and tidb_indexes.table_name = tidb_indexes.table_name
and tables.tidb_table_id = ?
and index_id = ?
TIDB_HOT_REGIONS table
The TIDB_HOT_REGIONS table provides the hot Region information in the current TiKV instance.
desc tidb_hot_regions\G
*************************** 1. row ***************************
Table: TIDB_HOT_REGIONS
Create Table: CREATE TABLE `TIDB_HOT_REGIONS` (
`TABLE_ID` bigint(21) unsigned DEFAULT NULL,
`INDEX_ID` bigint(21) unsigned DEFAULT NULL,
`DB_NAME` varchar(64) DEFAULT NULL,
`TABLE_NAME` varchar(64) DEFAULT NULL,
`INDEX_NAME` varchar(64) DEFAULT NULL,
`TYPE` varchar(64) DEFAULT NULL,
`MAX_HOT_DEGREE` bigint(21) unsigned DEFAULT NULL,
`REGION_COUNT` bigint(21) unsigned DEFAULT NULL,
`FLOW_BYTES` bigint(21) unsigned DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
1 row in set (0.00 sec)
TABLE_IDandINDEX_IDare IDs generated for the corresponding table and index in TiDB.TYPEis the type for a hot Region. Its value can beREADorWRITE.
TIKV_STORE_STATUS table
The TIKV_STORE_STATUS table shows some basic information of TiKV nodes via PD's API, like the ID allocated in the cluster, address and port, and status, capacity, and the number of Region leaders of the current node.
desc tikv_store_status\G
*************************** 1. row ***************************
Table: TIKV_STORE_STATUS
Create Table: CREATE TABLE `TIKV_STORE_STATUS` (
`STORE_ID` bigint(21) unsigned DEFAULT NULL,
`ADDRESS` varchar(64) DEFAULT NULL,
`STORE_STATE` bigint(21) unsigned DEFAULT NULL,
`STORE_STATE_NAME` varchar(64) DEFAULT NULL,
`LABEL` json unsigned DEFAULT NULL,
`VERSION` varchar(64) DEFAULT NULL,
`CAPACITY` varchar(64) DEFAULT NULL,
`AVAILABLE` varchar(64) DEFAULT NULL,
`LEADER_COUNT` bigint(21) unsigned DEFAULT NULL,
`LEADER_WEIGHT` bigint(21) unsigned DEFAULT NULL,
`LEADER_SCORE` bigint(21) unsigned DEFAULT NULL,
`LEADER_SIZE` bigint(21) unsigned DEFAULT NULL,
`REGION_COUNT` bigint(21) unsigned DEFAULT NULL,
`REGION_WEIGHT` bigint(21) unsigned DEFAULT NULL,
`REGION_SCORE` bigint(21) unsigned DEFAULT NULL,
`REGION_SIZE` bigint(21) unsigned DEFAULT NULL,
`START_TS` datetime unsigned DEFAULT NULL,
`LAST_HEARTBEAT_TS` datetime unsigned DEFAULT NULL,
`UPTIME` varchar(64) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
1 row in set (0.01 sec)
TIKV_REGION_STATUS table
The TIKV_REGION_STATUS table shows some basic information of TiKV Regions via PD's API, like the Region ID, starting and ending key-values, and read and write traffic.
desc tikv_region_status\G
*************************** 1. row ***************************
Table: TIKV_REGION_STATUS
Create Table: CREATE TABLE `TIKV_REGION_STATUS` (
`REGION_ID` bigint(21) unsigned DEFAULT NULL,
`START_KEY` text DEFAULT NULL,
`END_KEY` text DEFAULT NULL,
`EPOCH_CONF_VER` bigint(21) unsigned DEFAULT NULL,
`EPOCH_VERSION` bigint(21) unsigned DEFAULT NULL,
`WRITTEN_BYTES` bigint(21) unsigned DEFAULT NULL,
`READ_BYTES` bigint(21) unsigned DEFAULT NULL,
`APPROXIMATE_SIZE` bigint(21) unsigned DEFAULT NULL,
`APPROXIMATE_KEYS` bigint(21) unsigned DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
1 row in set (0.00 sec)
You can implement the top confver, top read and top write operations in pd-ctl via the ORDER BY X LIMIT Y operation on the EPOCH_CONF_VER, WRITTEN_BYTES and READ_BYTES columns.
You can query the top 3 Regions with the most write data using the following SQL statement:
select * from tikv_region_status order by written_bytes desc limit 3;
TIKV_REGION_PEERS table
The TIKV_REGION_PEERS table shows detailed information of a single Region node in TiKV, like whether it is a learner or leader.
desc tikv_region_peers\G
*************************** 1. row ***************************
Table: TIKV_REGION_PEERS
Create Table: CREATE TABLE `TIKV_REGION_PEERS` (
`REGION_ID` bigint(21) unsigned DEFAULT NULL,
`PEER_ID` bigint(21) unsigned DEFAULT NULL,
`STORE_ID` bigint(21) unsigned DEFAULT NULL,
`IS_LEARNER` tinyint(1) unsigned DEFAULT NULL,
`IS_LEADER` tinyint(1) unsigned DEFAULT NULL,
`STATUS` varchar(10) DEFAULT NULL,
`DOWN_SECONDS` bigint(21) unsigned DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
1 row in set (0.00 sec)
For example, you can query the specific TiKV addresses for the top 3 Regions with the maximum value of WRITTEN_BYTES using the following SQL statement:
select
address,
tikv.address,
region.region_id,
from
tikv_store_status tikv,
tikv_region_peers peer,
(
select
*
from
tikv_region_status region
order by
written_bytes desc limit 3
)
region
where
region.region_id = peer.region_id
and peer.is_leader = 1
and peer.store_id = tikv.region_id
ANALYZE_STATUS table
The ANALYZE_STATUS table shows the execution status of the ANALYZE command in the current cluster.
desc analyze_status\G
*************************** 1. row ***************************
Table: ANALYZE_STATUS
Create Table: CREATE TABLE `ANALYZE_STATUS` (
`TABLE_SCHEMA` varchar(64) DEFAULT NULL,
`TABLE_NAME` varchar(64) DEFAULT NULL,
`PARTITION_NAME` varchar(64) DEFAULT NULL,
`JOB_INFO` varchar(64) DEFAULT NULL,
`PROCESSED_ROWS` bigint(20) unsigned DEFAULT NULL,
`START_TIME` datetime unsigned DEFAULT NULL,
`STATE` varchar(64) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
1 row in set (0.00 sec)
The STATE column shows the execution status of a specific ANALYZE task. Its value can be pending, running,finished or failed.
SLOW_QUERY table
The SLOW_QUERY table maps slow query logs. Its column names and field names of slow query logs have an one-to-one corresponse relationship. For details, see Identify Slow Queries.
desc slow_query\G
*************************** 1. row ***************************
Table: SLOW_QUERY
Create Table: CREATE TABLE `SLOW_QUERY` (
`Time` timestamp unsigned NULL DEFAULT NULL,
`Txn_start_ts` bigint(20) unsigned DEFAULT NULL,
`User` varchar(64) DEFAULT NULL,
`Host` varchar(64) DEFAULT NULL,
`Conn_ID` bigint(20) unsigned DEFAULT NULL,
`Query_time` double unsigned DEFAULT NULL,
`Process_time` double unsigned DEFAULT NULL,
`Wait_time` double unsigned DEFAULT NULL,
`Backoff_time` double unsigned DEFAULT NULL,
`Request_count` bigint(20) unsigned DEFAULT NULL,
`Total_keys` bigint(20) unsigned DEFAULT NULL,
`Process_keys` bigint(20) unsigned DEFAULT NULL,
`DB` varchar(64) DEFAULT NULL,
`Index_ids` varchar(100) DEFAULT NULL,
`Is_internal` tinyint(1) unsigned DEFAULT NULL,
`Digest` varchar(64) DEFAULT NULL,
`Stats` varchar(512) DEFAULT NULL,
`Cop_proc_avg` double unsigned DEFAULT NULL,
`Cop_proc_p90` double unsigned DEFAULT NULL,
`Cop_proc_max` double unsigned DEFAULT NULL,
`Cop_proc_addr` varchar(64) DEFAULT NULL,
`Cop_wait_avg` double unsigned DEFAULT NULL,
`Cop_wait_p90` double unsigned DEFAULT NULL,
`Cop_wait_max` double unsigned DEFAULT NULL,
`Cop_wait_addr` varchar(64) DEFAULT NULL,
`Mem_max` bigint(20) unsigned DEFAULT NULL,
`Query` varchar(4096) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
1 row in set (0.00 sec)
Unsupported Information Schema Tables
The following INFORMATION_SCHEMA tables are present in TiDB, but will always return zero rows:
COLUMN_PRIVILEGESEVENTSFILESGLOBAL_STATUSGLOBAL_VARIABLESOPTIMIZER_TRACEPARAMETERSPARTITIONSPLUGINSPROFILINGREFERENTIAL_CONSTRAINTSROUTINESSCHEMA_PRIVILEGESSESSION_STATUSTABLESPACESTABLE_PRIVILEGESTRIGGERS