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ADD COLUMNADD INDEXADMINADMIN CANCEL DDLADMIN CHECKSUM TABLEADMIN CHECK [TABLE|INDEX]ADMIN SHOW DDL [JOBS|QUERIES]ALTER DATABASEALTER INDEXALTER TABLEALTER TABLE COMPACTALTER USERANALYZE TABLEBATCHBEGINCHANGE COLUMNCOMMITCHANGE DRAINERCHANGE PUMPCREATE [GLOBAL|SESSION] BINDINGCREATE DATABASECREATE INDEXCREATE ROLECREATE SEQUENCECREATE TABLE LIKECREATE TABLECREATE USERCREATE VIEWDEALLOCATEDELETEDESCDESCRIBEDODROP [GLOBAL|SESSION] BINDINGDROP COLUMNDROP DATABASEDROP INDEXDROP ROLEDROP SEQUENCEDROP STATSDROP TABLEDROP USERDROP VIEWEXECUTEEXPLAIN ANALYZEEXPLAINFLASHBACK TABLEFLUSH PRIVILEGESFLUSH STATUSFLUSH TABLESGRANT <privileges>GRANT <role>INSERTKILL [TIDB]MODIFY COLUMNPREPARERECOVER TABLERENAME INDEXRENAME TABLEREPLACEREVOKE <privileges>REVOKE <role>ROLLBACKSELECTSET DEFAULT ROLESET [NAMES|CHARACTER SET]SET PASSWORDSET ROLESET TRANSACTIONSET [GLOBAL|SESSION] <variable>SHOW ANALYZE STATUSSHOW [GLOBAL|SESSION] BINDINGSSHOW BUILTINSSHOW CHARACTER SETSHOW COLLATIONSHOW [FULL] COLUMNS FROMSHOW CREATE SEQUENCESHOW CREATE TABLESHOW CREATE USERSHOW DATABASESSHOW DRAINER STATUSSHOW ENGINESSHOW ERRORSSHOW [FULL] FIELDS FROMSHOW GRANTSSHOW INDEX [FROM|IN]SHOW INDEXES [FROM|IN]SHOW KEYS [FROM|IN]SHOW MASTER STATUSSHOW PLUGINSSHOW PRIVILEGESSHOW [FULL] PROCESSSLISTSHOW PROFILESSHOW PUMP STATUSSHOW SCHEMASSHOW STATS_HEALTHYSHOW STATS_HISTOGRAMSSHOW STATS_METASHOW STATUSSHOW TABLE NEXT_ROW_IDSHOW TABLE REGIONSSHOW TABLE STATUSSHOW [FULL] TABLESSHOW [GLOBAL|SESSION] VARIABLESSHOW WARNINGSSHUTDOWNSPLIT REGIONSTART TRANSACTIONTABLETRACETRUNCATEUPDATEUSEWITH
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mysql- INFORMATION_SCHEMA
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ANALYZE_STATUSCLIENT_ERRORS_SUMMARY_BY_HOSTCLIENT_ERRORS_SUMMARY_BY_USERCLIENT_ERRORS_SUMMARY_GLOBALCHARACTER_SETSCLUSTER_INFOCOLLATIONSCOLLATION_CHARACTER_SET_APPLICABILITYCOLUMNSDATA_LOCK_WAITSDDL_JOBSDEADLOCKSENGINESKEY_COLUMN_USAGEPARTITIONSPROCESSLISTREFERENTIAL_CONSTRAINTSSCHEMATASEQUENCESSESSION_VARIABLESSLOW_QUERYSTATISTICSTABLESTABLE_CONSTRAINTSTABLE_STORAGE_STATSTIDB_HOT_REGIONS_HISTORYTIDB_INDEXESTIDB_SERVERS_INFOTIDB_TRXTIFLASH_REPLICATIKV_REGION_PEERSTIKV_REGION_STATUSTIKV_STORE_STATUSUSER_PRIVILEGESVIEWS
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SLOW_QUERY
The SLOW_QUERY table provides the slow query information of the current node, 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, see Slow Query Log Document.
USE information_schema;
DESC slow_query;
+---------------------------+---------------------+------+------+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------------------+---------------------+------+------+---------+-------+
| Time | timestamp(6) | 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 | YES | | NULL | |
| Parse_time | double | YES | | NULL | |
| Compile_time | double | YES | | NULL | |
| Rewrite_time | double | YES | | NULL | |
| Preproc_subqueries | bigint(20) unsigned | YES | | NULL | |
| Preproc_subqueries_time | double | YES | | NULL | |
| Optimize_time | double | YES | | NULL | |
| Wait_TS | double | YES | | NULL | |
| Prewrite_time | double | YES | | NULL | |
| Wait_prewrite_binlog_time | double | YES | | NULL | |
| Commit_time | double | YES | | NULL | |
| Get_commit_ts_time | double | YES | | NULL | |
| Commit_backoff_time | double | YES | | NULL | |
| Backoff_types | varchar(64) | YES | | NULL | |
| Resolve_lock_time | double | YES | | NULL | |
| Local_latch_wait_time | double | YES | | NULL | |
| Write_keys | bigint(22) | YES | | NULL | |
| Write_size | bigint(22) | YES | | NULL | |
| Prewrite_region | bigint(22) | YES | | NULL | |
| Txn_retry | bigint(22) | YES | | NULL | |
| Cop_time | double | YES | | NULL | |
| Process_time | double | YES | | NULL | |
| Wait_time | double | YES | | NULL | |
| Backoff_time | double | YES | | NULL | |
| LockKeys_time | double | 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_names | varchar(100) | YES | | NULL | |
| Is_internal | tinyint(1) | YES | | NULL | |
| Digest | varchar(64) | YES | | NULL | |
| Stats | varchar(512) | YES | | NULL | |
| Cop_proc_avg | double | YES | | NULL | |
| Cop_proc_p90 | double | YES | | NULL | |
| Cop_proc_max | double | YES | | NULL | |
| Cop_proc_addr | varchar(64) | YES | | NULL | |
| Cop_wait_avg | double | YES | | NULL | |
| Cop_wait_p90 | double | YES | | NULL | |
| Cop_wait_max | double | YES | | NULL | |
| Cop_wait_addr | varchar(64) | YES | | NULL | |
| Mem_max | bigint(20) | YES | | NULL | |
| Disk_max | bigint(20) | YES | | NULL | |
| Succ | tinyint(1) | YES | | NULL | |
| Plan_from_cache | tinyint(1) | YES | | NULL | |
| Plan | longblob | YES | | NULL | |
| Plan_digest | varchar(128) | YES | | NULL | |
| Prev_stmt | longblob | YES | | NULL | |
| Query | longblob | YES | | NULL | |
+---------------------------+---------------------+------+------+---------+-------+
54 rows in set (0.00 sec)
CLUSTER_SLOW_QUERY table
The CLUSTER_SLOW_QUERY table provides the slow query information of all nodes in the cluster, which is the parsing result of the TiDB slow log files. You can use the CLUSTER_SLOW_QUERY table the way you do with SLOW_QUERY. The table schema of the CLUSTER_SLOW_QUERY table differs from that of the SLOW_QUERY table in that an INSTANCE column is added to CLUSTER_SLOW_QUERY. The INSTANCE column represents the TiDB node address of the row information on the slow query.
For how to use this table to identify problematic statements and improve query performance, see Slow Query Log Document.
desc cluster_slow_query;
+---------------------------+---------------------+------+------+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------------------+---------------------+------+------+---------+-------+
| INSTANCE | varchar(64) | YES | | NULL | |
| Time | timestamp(6) | 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 | YES | | NULL | |
| Parse_time | double | YES | | NULL | |
| Compile_time | double | YES | | NULL | |
| Rewrite_time | double | YES | | NULL | |
| Preproc_subqueries | bigint(20) unsigned | YES | | NULL | |
| Preproc_subqueries_time | double | YES | | NULL | |
| Optimize_time | double | YES | | NULL | |
| Wait_TS | double | YES | | NULL | |
| Prewrite_time | double | YES | | NULL | |
| Wait_prewrite_binlog_time | double | YES | | NULL | |
| Commit_time | double | YES | | NULL | |
| Get_commit_ts_time | double | YES | | NULL | |
| Commit_backoff_time | double | YES | | NULL | |
| Backoff_types | varchar(64) | YES | | NULL | |
| Resolve_lock_time | double | YES | | NULL | |
| Local_latch_wait_time | double | YES | | NULL | |
| Write_keys | bigint(22) | YES | | NULL | |
| Write_size | bigint(22) | YES | | NULL | |
| Prewrite_region | bigint(22) | YES | | NULL | |
| Txn_retry | bigint(22) | YES | | NULL | |
| Cop_time | double | YES | | NULL | |
| Process_time | double | YES | | NULL | |
| Wait_time | double | YES | | NULL | |
| Backoff_time | double | YES | | NULL | |
| LockKeys_time | double | 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_names | varchar(100) | YES | | NULL | |
| Is_internal | tinyint(1) | YES | | NULL | |
| Digest | varchar(64) | YES | | NULL | |
| Stats | varchar(512) | YES | | NULL | |
| Cop_proc_avg | double | YES | | NULL | |
| Cop_proc_p90 | double | YES | | NULL | |
| Cop_proc_max | double | YES | | NULL | |
| Cop_proc_addr | varchar(64) | YES | | NULL | |
| Cop_wait_avg | double | YES | | NULL | |
| Cop_wait_p90 | double | YES | | NULL | |
| Cop_wait_max | double | YES | | NULL | |
| Cop_wait_addr | varchar(64) | YES | | NULL | |
| Mem_max | bigint(20) | YES | | NULL | |
| Disk_max | bigint(20) | YES | | NULL | |
| Succ | tinyint(1) | YES | | NULL | |
| Plan_from_cache | tinyint(1) | YES | | NULL | |
| Plan | longblob | YES | | NULL | |
| Plan_digest | varchar(128) | YES | | NULL | |
| Prev_stmt | longblob | YES | | NULL | |
| Query | longblob | YES | | NULL | |
+---------------------------+---------------------+------+------+---------+-------+
55 rows in set (0.00 sec)
When the cluster system table is queried, TiDB does not obtain data from all nodes, but pushes down the related calculation to other nodes. The execution plan is as follows:
desc SELECT count(*) FROM cluster_slow_query WHERE user = 'u1';
+--------------------------+----------+-----------+--------------------------+------------------------------------------------------+
| id | estRows | task | access object | operator info |
+--------------------------+----------+-----------+--------------------------+------------------------------------------------------+
| StreamAgg_20 | 1.00 | root | | funcs:count(Column#53)->Column#51 |
| └─TableReader_21 | 1.00 | root | | data:StreamAgg_9 |
| └─StreamAgg_9 | 1.00 | cop[tidb] | | funcs:count(1)->Column#53 |
| └─Selection_19 | 10.00 | cop[tidb] | | eq(information_schema.cluster_slow_query.user, "u1") |
| └─TableFullScan_18 | 10000.00 | cop[tidb] | table:CLUSTER_SLOW_QUERY | keep order:false, stats:pseudo |
+--------------------------+----------+-----------+--------------------------+------------------------------------------------------+
In the above execution plan, the user = u1 condition is pushed down to other (cop) TiDB nodes, and the aggregate operator is also pushed down (the StreamAgg operator in the graph).
Currently, because statistics of the system tables are not collected, sometimes some aggregation operators cannot be pushed down, which results in slow execution. In this case, you can manually specify the SQL HINT to push down the aggregation operators. For example:
SELECT /*+ AGG_TO_COP() */ count(*) FROM cluster_slow_query GROUP BY user;
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