DRDS
目录
SHOW HELP
| STATEMENT | DESCRIPTION_CN | DESCRIPTION | EXAMPLE |
|---|---|---|---|
| show rule | 查看所有表分片信息 | Report all table rule | |
| show rule from TABLE | 查看具体表分片信息 | Report table rule | show rule from user |
| show full rule from TABLE | 查看具体表详细分片信息 | Report table full rule | show full rule from user |
| show topology from TABLE | 查看具体物理库表 | Report table physical topology | show topology from user |
| show partitions from TABLE | 查看具体表分片列 | Report table dbPartition or tbPartition columns | show partitions from user |
| show broadcasts | 查看所有广播表 | Report all broadcast tables | |
| show datasources | 查看所有分库连接池信息 | Report all partition db threadPool info | |
| show node | 查看所有分库主从读信息 | Report master/slave read status | |
| show slow | 查看DRDS监控下的慢SQL | Report top 100 slow sql | |
| show physical_slow | 查看RDS监控下的慢SQL | Report top 100 physical slow sql | |
| clear slow | 清空慢SQL | Clear slow data | |
| trace SQL | 跟踪慢SQL不执行 | Start trace sql, use show trace to print profiling data | trace select count(*) from user; show trace |
| show trace | 显示跟踪 | Report sql execute profiling info | |
| explain SQL | 执行计划 | Report sql plan info | explain select count(*) from user |
| explain detail SQL | 详细执行计划 | Report sql detail plan info | explain detail select count(*) from user |
| explain execute SQL | 物理节点执行计划 | Report sql on physical db plan info | explain execute select count(*) from user |
| show sequences | Report all sequences status | ||
| create sequence NAME [start with COUNT] | Create sequence | create sequence test start with 0 | |
| alter sequence NAME [start with COUNT] | Alter sequence | alter sequence test start with 100000 | |
| drop sequence NAME | Drop sequence | drop sequence test | |
| show db status | 查看物理节点空间信息 | Report size of each physical database | show db status |
| show full db status | 查看物理节点表占用空间信息 | Report size of each physical table, support like | show full db status like user |
| show ds | 查看简单分库信息 | Report simple partition db info | show ds |
| show connection | 查看所有连接信息 | Report all connections info | show connection |
| show trans | 查看所有事物信息 | Report trans info | show trans/show trans limit 2 |
| show full trans | 查看所有事物详细信息 | Report all trans info | show full trans/show full trans limit 2 |
| show stats | 查看请求信息的统计信息 | Report all requst stats | show stats |
| show stc | 查看所有分库的请求信息 | Report all requst stats by partition | show stc |
| show htc | 查看所有分库的CPU/内存信息 | Report the CPU/LOAD/MEM/NET/GC stats | show htc |
| show outlines | Report outlines | show outlines |
EXPLAIN
语法
EXPLAIN
{LOGICALVIEW | LOGIC | SIMPLE | DETAIL | EXECUTE | PHYSICAL | OPTIMIZER | SHARDING
| COST | ANALYZE | BASELINE | JSON_PLAN | ADVISOR}
{SELECT statement | DELETE statement | INSERT statement | REPLACE statement| UPDATE statement}
EXPLAIN语句
展示基本的SQL执行计划，该执行计划是算子组成，主要体现SQL在CN上的整个执行过程。
EXPLAIN select count(*) from lineitem group by L_ORDERKEY;
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| LOGICAL EXECUTIONPLAN |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Project(count(*)="count(*)") |
| HashAgg(group="L_ORDERKEY", count(*)="SUM(count(*))") |
| Gather(concurrent=true) |
| LogicalView(tables="[000000-000003].lineitem_[00-15]", shardCount=16, sql="SELECT `L_ORDERKEY`, COUNT(*) AS `count(*)` FROM `lineitem` AS `lineitem` GROUP BY `L_ORDERKEY`") |
| HitCache:false | |
| TemplateId: 5819c807 |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
其中，HitCache标记该查询是否命中PlanCache，取值为falseortrue；TemplateId表示对该计划的标识，具有全局唯一性。
EXPLAIN LOGICALVIEW语句
展示基本的SQL执行计划，该执行计划是算子组成，主要体现SQL在CN上的整个执行过程。
EXPLAIN LOGICALVIEW select count(*) from lineitem group by L_ORDERKEY;
+----------------------------------------------------------+
| LOGICAL EXECUTIONPLAN |
+----------------------------------------------------------+
| Project(count(*)="count(*)") |
| HashAgg(group="L_ORDERKEY", count(*)="SUM(count(*))") |
| Gather(concurrent=true) |
| LogicalView |
| MysqlAgg(group="L_ORDERKEY", count(*)="COUNT()") |
| MysqlTableScan(name=[ads, lineitem]) |
| HitCache:true |
| Source:PLAN_CACHE |
| TemplateId: 5819c807
EXPLAIN EXECUTE语句
表示下推SQL在MySQL的执行情况，这个语句和MySQL的explain语句同义。通过该语句可以查看下推SQL在DN上有没有使用索引，有没有做全表扫描。
EXPLAIN EXECUTE select count(*) from lineitem group by L_ORDERKEY;
+----+-------------+----------+------------+-------+---------------+---------+---------+-----+------+----------+----------------------------------------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+----------+------------+-------+---------------+---------+---------+-----+------+----------+----------------------------------------------+
| 1 | SIMPLE | lineitem | NULL | index | PRIMARY | PRIMARY | 8 | NULL | 1 | 100 | Using index; Using temporary; Using filesort |
+----+-------------+----------+------------+-------+---------------+---------+---------+-----+------+----------+----------------------------------------------+
1 row in set (0.24 sec)
EXPLAIN SHARDING语句
展示当前查询在DN上扫描的物理分片情况。
EXPLAIN SHARDING select count(*) from lineitem group by L_ORDERKEY;
+---------------+----------------------------------+-------------+-----------+-----------+
| LOGICAL_TABLE | SHARDING | SHARD_COUNT | BROADCAST | CONDITION |
+---------------+----------------------------------+-------------+-----------+-----------+
| lineitem | [000000-000003].lineitem_[00-15] | 16 | false | |
+---------------+----------------------------------+-------------+-----------+-----------+
1 row in set (0.04 sec)
EXPLAIN COST语句
相对于EXPLAIN语句，除了展示执行计划以外，还会显示各个算子基于统计信息估算的代价，以及这条查询被优化器识别的WORKLOAD。
EXPLAIN COST select count(*) from lineitem group by L_ORDERKEY;
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| LOGICAL EXECUTIONPLAN |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Project(count(*)="count(*)"): rowcount = 2508.0, cumulative cost = value = 2.4867663E7, cpu = 112574.0, memory = 88984.0, io = 201.0, net = 4.75, id = 182 |
| HashAgg(group="L_ORDERKEY", count(*)="SUM(count(*))"): rowcount = 2508.0, cumulative cost = value = 2.4867662E7, cpu = 112573.0, memory = 88984.0, io = 201.0, net = 4.75, id = 180 |
| Gather(concurrent=true): rowcount = 2508.0, cumulative cost = value = 2.4860069E7, cpu = 105039.0, memory = 29796.0, io = 201.0, net = 4.75, id = 178 |
| LogicalView(tables="[000000-000003].lineitem_[00-15]", shardCount=16, sql="SELECT `L_ORDERKEY`, COUNT(*) AS `count(*)` FROM `lineitem` AS `lineitem` GROUP BY `L_ORDERKEY`"): rowcount = 2508.0, cumulative cost = value = 2.4860068E7, cpu = 105038.0, memory = 29796.0, io = 201.0, net = 4.75, id = 109 |
| HitCache:true |
| Source:PLAN_CACHE |
| WorkloadType: TP |
| TemplateId: 5819c807
EXPLAIN ANALYZE语句
相对于explain cost语句，除了显示各个算子基于统计信息估算的代价以外，该语句可以收集真实运行过程中算子输出的rowCount等信息。
EXPLAIN ANALYZE select count(*) from lineitem group by L_ORDERKEY;
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| LOGICAL EXECUTIONPLAN |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Project(count(*)="count(*)"): rowcount = 2508.0, cumulative cost = value = 2.4867663E7, cpu = 112574.0, memory = 88984.0, io = 201.0, net = 4.75, actual time = 0.001 + 0.000, actual rowcount = 2506, actual memory = 0, instances = 1, id = 182 |
| HashAgg(group="L_ORDERKEY", count(*)="SUM(count(*))"): rowcount = 2508.0, cumulative cost = value = 2.4867662E7, cpu = 112573.0, memory = 88984.0, io = 201.0, net = 4.75, actual time = 0.000 + 0.000, actual rowcount = 2506, actual memory = 0, instances = 1, id = 180 |
| Gather(concurrent=true): rowcount = 2508.0, cumulative cost = value = 2.4860069E7, cpu = 105039.0, memory = 29796.0, io = 201.0, net = 4.75, actual time = 0.000 + 0.000, actual rowcount = 0, actual memory = 0, instances = 0, id = 178 |
| LogicalView(tables="[000000-000003].lineitem_[00-15]", shardCount=16, sql="SELECT `L_ORDERKEY`, COUNT(*) AS `count(*)` FROM `lineitem` AS `lineitem` GROUP BY `L_ORDERKEY`"): rowcount = 2508.0, cumulative cost = value = 2.4860068E7, cpu = 105038.0, memory = 29796.0, io = 201.0, net = 4.75, actual time = 0.030 + 0.025, actual rowcount = 10000, actual memory = 0, instances = 0, id = 109 |
| HitCache:true |
| Source:PLAN_CACHE |
| TemplateId: 5819c807 |
+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
7 rows in set (1.08 sec)
EXPLAIN PHYSICAL语句
展示查询在运行过程中执行模式、各个执行片段（Fragment）的依赖关系和并行度。该查询被识别为单机单线程计划模式（TP_LOCAL），执行计划被分为三个片段Fragment-0、Fragment-1和Fragment-2，先做预聚合再做最终的聚合计算，每个片段的执行度可以不同。
EXPLAIN PHYSICAL select count(*) from lineitem group by L_ORDERKEY;
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| PLAN |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| ExecutorMode: TP_LOCAL |
| Fragment 0 dependency: [] parallelism: 4 |
| Gather(concurrent=true) |
| LogicalView(tables="[000000-000003].lineitem_[00-15]", shardCount=16, sql="SELECT `L_ORDERKEY`, COUNT(*) AS `count(*)` FROM `lineitem` AS `lineitem` GROUP BY `L_ORDERKEY`") |
| Fragment 1 dependency: [] parallelism: 8 |
| LocalBuffer |
| RemoteSource(sourceFragmentIds=[0], type=RecordType(INTEGER L_ORDERKEY, BIGINT count(*))) |
| Fragment 2 dependency: [0, 1] parallelism: 8 |
| Project(count(*)="count(*)") |
| HashAgg(group="L_ORDERKEY", count(*)="SUM(count(*))") |
| RemoteSource(sourceFragmentIds=[1], type=RecordType(INTEGER L_ORDERKEY, BIGINT count(*))) |
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
11 rows in set (0.10 sec)
EXPLAIN ADVISOR语句
基于统计信息，分析当前查询的执行计划，给用户推荐可以加速查询的全局二级索引。
EXPLAIN ADVISOR select count(*) from lineitem group by L_ORDERKEY \G;
*************************** 1. row ***************************
IMPROVE_VALUE: 4.4%
IMPROVE_CPU: 340.8%
IMPROVE_MEM: 0.0%
IMPROVE_IO: 1910.0%
IMPROVE_NET: 0.0%
BEFORE_VALUE: 2.48676627E7
BEFORE_CPU: 112573.7
BEFORE_MEM: 88983.8
BEFORE_IO: 201
BEFORE_NET: 4.7
AFTER_VALUE: 2.38256249E7
AFTER_CPU: 25536
AFTER_MEM: 88983.8
AFTER_IO: 10
AFTER_NET: 4.7
ADVISE_INDEX: ALTER TABLE `ads`.`lineitem` ADD GLOBAL INDEX `__advise_index_gsi_lineitem_L_ORDERKEY`(`L_ORDERKEY`) DBPARTITION BY HASH(`L_ORDERKEY`) TBPARTITION BY HASH(`L_ORDERKEY`) TBPARTITIONS 4;
NEW_PLAN:
Project(count(*)="count(*)")
HashAgg(group="L_ORDERKEY", count(*)="SUM(count(*))")
Gather(concurrent=true)
IndexScan(tables="[000000-000003].lineitem__what_if_gsi_L_ORDERKEY_[00-15]", shardCount=16, sql="SELECT `L_ORDERKEY`, COUNT(*) AS `count(*)` FROM `lineitem__what_if_gsi_L_ORDERKEY` AS `lineitem__what_if_gsi_L_ORDERKEY` GROUP BY `L_ORDERKEY`")
INFO: GLOBAL_INDEX
1 row in set (0.13 sec)
CHECK TABLE
CHECK TABLE用于对数据表进行检查，主要用于DDL建表失败的情形。
- 对于拆分表，检查底层物理分表是否有缺失的情况，底层的物理分表的列和索引是否一致；
- 对于单库单表，检查表是否存在。
语法
CHECK TABLE tbl_name
示例
CHECK TABLE tddl_mgr_log;
+------------------------+-------+----------+----------+
| TABLE | OP | MSG_TYPE | MSG_TEXT |
+------------------------+-------+----------+----------+
| TDDL5_APP.tddl_mgr_log | check | status | OK |
+------------------------+-------+----------+----------+
1 row in set (0.56 sec)
CHECK TABLE tddl_mg;
+-------------------+-------+----------+----------------------------------------+
| TABLE | OP | MSG_TYPE | MSG_TEXT |
+-------------------+-------+----------+----------------------------------------+
| TDDL5_APP.tddl_mg | check | Error | Table 'tddl5_00.tddl_mg' doesn't exist |
+-------------------+-------+----------+----------------------------------------+
1 row in set (0.02 sec)
逻辑表的拓扑分布
查看指定逻辑表的拓扑分布，展示该逻辑表保存在哪些分库中，每个分库下包含哪些分表。
语法
SHOW PARTITIONS FROM tablename
示例
mysql> SHOW TOPOLOGY FROM test_table;
+-----+------------------------------------+---------------------+
| ID | GROUP_NAME | TABLE_NAME |
+-----+------------------------------------+---------------------+
| 0 | DB_1631610412546HSWK_0LNF_0000 | test_table_Oenl_000 |
| 1 | DB_1631610412546HSWK_0LNF_0000 | test_table_Oenl_001 |
| 2 | DB_1631610412546HSWK_0LNF_0000 | test_table_Oenl_002 |
| 3 | DB_1631610412546HSWK_0LNF_0000 | test_table_Oenl_003 |
| 4 | DB_1631610412546HSWK_0LNF_0000 | test_table_Oenl_004 |
| 5 | DB_1631610412546HSWK_0LNF_0000 | test_table_Oenl_005 |
| 6 | DB_1631610412546HSWK_0LNF_0000 | test_table_Oenl_006 |
| 7 | DB_1631610412546HSWK_0LNF_0000 | test_table_Oenl_007 |
| 8 | DB_1631610412546HSWK_0LNF_0001 | test_table_Oenl_008 |
| 9 | DB_1631610412546HSWK_0LNF_0001 | test_table_Oenl_009 |
| 10 | DB_1631610412546HSWK_0LNF_0001 | test_table_Oenl_010 |
| 11 | DB_1631610412546HSWK_0LNF_0001 | test_table_Oenl_011 |
| 12 | DB_1631610412546HSWK_0LNF_0001 | test_table_Oenl_012 |
| 13 | DB_1631610412546HSWK_0LNF_0001 | test_table_Oenl_013 |
| 14 | DB_1631610412546HSWK_0LNF_0001 | test_table_Oenl_014 |
| 15 | DB_1631610412546HSWK_0LNF_0001 | test_table_Oenl_015 |
| 16 | DB_1631610412546HSWK_0LNF_0002 | test_table_Oenl_016 |
| 17 | DB_1631610412546HSWK_0LNF_0002 | test_table_Oenl_017 |
| 18 | DB_1631610412546HSWK_0LNF_0002 | test_table_Oenl_018 |
| 19 | DB_1631610412546HSWK_0LNF_0002 | test_table_Oenl_019 |
| 20 | DB_1631610412546HSWK_0LNF_0002 | test_table_Oenl_020 |
| 21 | DB_1631610412546HSWK_0LNF_0002 | test_table_Oenl_021 |
| 22 | DB_1631610412546HSWK_0LNF_0002 | test_table_Oenl_022 |
| 23 | DB_1631610412546HSWK_0LNF_0002 | test_table_Oenl_023 |
| 24 | DB_1631610412546HSWK_0LNF_0003 | test_table_Oenl_024 |
| 25 | DB_1631610412546HSWK_0LNF_0003 | test_table_Oenl_025 |
| 26 | DB_1631610412546HSWK_0LNF_0003 | test_table_Oenl_026 |
| 27 | DB_1631610412546HSWK_0LNF_0003 | test_table_Oenl_027 |
| 28 | DB_1631610412546HSWK_0LNF_0003 | test_table_Oenl_028 |
| 29 | DB_1631610412546HSWK_0LNF_0003 | test_table_Oenl_029 |
| 30 | DB_1631610412546HSWK_0LNF_0003 | test_table_Oenl_030 |
| 31 | DB_1631610412546HSWK_0LNF_0003 | test_table_Oenl_031 |
| 32 | DB_1631610412546HSWK_0LNF_0004 | test_table_Oenl_032 |
| 33 | DB_1631610412546HSWK_0LNF_0004 | test_table_Oenl_033 |
| 34 | DB_1631610412546HSWK_0LNF_0004 | test_table_Oenl_034 |
| 35 | DB_1631610412546HSWK_0LNF_0004 | test_table_Oenl_035 |
| 36 | DB_1631610412546HSWK_0LNF_0004 | test_table_Oenl_036 |
| 37 | DB_1631610412546HSWK_0LNF_0004 | test_table_Oenl_037 |
| 38 | DB_1631610412546HSWK_0LNF_0004 | test_table_Oenl_038 |
| 39 | DB_1631610412546HSWK_0LNF_0004 | test_table_Oenl_039 |
| 40 | DB_1631610412546HSWK_0LNF_0005 | test_table_Oenl_040 |
| 41 | DB_1631610412546HSWK_0LNF_0005 | test_table_Oenl_041 |
| 42 | DB_1631610412546HSWK_0LNF_0005 | test_table_Oenl_042 |
| 43 | DB_1631610412546HSWK_0LNF_0005 | test_table_Oenl_043 |
| 44 | DB_1631610412546HSWK_0LNF_0005 | test_table_Oenl_044 |
| 45 | DB_1631610412546HSWK_0LNF_0005 | test_table_Oenl_045 |
| 46 | DB_1631610412546HSWK_0LNF_0005 | test_table_Oenl_046 |
| 47 | DB_1631610412546HSWK_0LNF_0005 | test_table_Oenl_047 |
| 48 | DB_1631610412546HSWK_0LNF_0006 | test_table_Oenl_048 |
| 49 | DB_1631610412546HSWK_0LNF_0006 | test_table_Oenl_049 |
| 50 | DB_1631610412546HSWK_0LNF_0006 | test_table_Oenl_050 |
| 51 | DB_1631610412546HSWK_0LNF_0006 | test_table_Oenl_051 |
| 52 | DB_1631610412546HSWK_0LNF_0006 | test_table_Oenl_052 |
| 53 | DB_1631610412546HSWK_0LNF_0006 | test_table_Oenl_053 |
| 54 | DB_1631610412546HSWK_0LNF_0006 | test_table_Oenl_054 |
| 55 | DB_1631610412546HSWK_0LNF_0006 | test_table_Oenl_055 |
| 56 | DB_1631610412546HSWK_0LNF_0007 | test_table_Oenl_056 |
| 57 | DB_1631610412546HSWK_0LNF_0007 | test_table_Oenl_057 |
| 58 | DB_1631610412546HSWK_0LNF_0007 | test_table_Oenl_058 |
| 59 | DB_1631610412546HSWK_0LNF_0007 | test_table_Oenl_059 |
| 60 | DB_1631610412546HSWK_0LNF_0007 | test_table_Oenl_060 |
| 61 | DB_1631610412546HSWK_0LNF_0007 | test_table_Oenl_061 |
| 62 | DB_1631610412546HSWK_0LNF_0007 | test_table_Oenl_062 |
| 63 | DB_1631610412546HSWK_0LNF_0007 | test_table_Oenl_063 |
| 64 | DB_1631610412546HSWK_0LNF_0008 | test_table_Oenl_064 |
| 65 | DB_1631610412546HSWK_0LNF_0008 | test_table_Oenl_065 |
| 66 | DB_1631610412546HSWK_0LNF_0008 | test_table_Oenl_066 |
| 67 | DB_1631610412546HSWK_0LNF_0008 | test_table_Oenl_067 |
| 68 | DB_1631610412546HSWK_0LNF_0008 | test_table_Oenl_068 |
| 69 | DB_1631610412546HSWK_0LNF_0008 | test_table_Oenl_069 |
| 70 | DB_1631610412546HSWK_0LNF_0008 | test_table_Oenl_070 |
| 71 | DB_1631610412546HSWK_0LNF_0008 | test_table_Oenl_071 |
| 72 | DB_1631610412546HSWK_0LNF_0009 | test_table_Oenl_072 |
| 73 | DB_1631610412546HSWK_0LNF_0009 | test_table_Oenl_073 |
| 74 | DB_1631610412546HSWK_0LNF_0009 | test_table_Oenl_074 |
| 75 | DB_1631610412546HSWK_0LNF_0009 | test_table_Oenl_075 |
| 76 | DB_1631610412546HSWK_0LNF_0009 | test_table_Oenl_076 |
| 77 | DB_1631610412546HSWK_0LNF_0009 | test_table_Oenl_077 |
| 78 | DB_1631610412546HSWK_0LNF_0009 | test_table_Oenl_078 |
| 79 | DB_1631610412546HSWK_0LNF_0009 | test_table_Oenl_079 |
| 80 | DB_1631610412546HSWK_0LNF_0010 | test_table_Oenl_080 |
| 81 | DB_1631610412546HSWK_0LNF_0010 | test_table_Oenl_081 |
| 82 | DB_1631610412546HSWK_0LNF_0010 | test_table_Oenl_082 |
| 83 | DB_1631610412546HSWK_0LNF_0010 | test_table_Oenl_083 |
| 84 | DB_1631610412546HSWK_0LNF_0010 | test_table_Oenl_084 |
| 85 | DB_1631610412546HSWK_0LNF_0010 | test_table_Oenl_085 |
| 86 | DB_1631610412546HSWK_0LNF_0010 | test_table_Oenl_086 |
| 87 | DB_1631610412546HSWK_0LNF_0010 | test_table_Oenl_087 |
| 88 | DB_1631610412546HSWK_0LNF_0011 | test_table_Oenl_088 |
| 89 | DB_1631610412546HSWK_0LNF_0011 | test_table_Oenl_089 |
| 90 | DB_1631610412546HSWK_0LNF_0011 | test_table_Oenl_090 |
| 91 | DB_1631610412546HSWK_0LNF_0011 | test_table_Oenl_091 |
| 92 | DB_1631610412546HSWK_0LNF_0011 | test_table_Oenl_092 |
| 93 | DB_1631610412546HSWK_0LNF_0011 | test_table_Oenl_093 |
| 94 | DB_1631610412546HSWK_0LNF_0011 | test_table_Oenl_094 |
| 95 | DB_1631610412546HSWK_0LNF_0011 | test_table_Oenl_095 |
| 96 | DB_1631610412546HSWK_0LNF_0012 | test_table_Oenl_096 |
| 97 | DB_1631610412546HSWK_0LNF_0012 | test_table_Oenl_097 |
| 98 | DB_1631610412546HSWK_0LNF_0012 | test_table_Oenl_098 |
| 99 | DB_1631610412546HSWK_0LNF_0012 | test_table_Oenl_099 |
| 100 | DB_1631610412546HSWK_0LNF_0012 | test_table_Oenl_100 |
| 101 | DB_1631610412546HSWK_0LNF_0012 | test_table_Oenl_101 |
| 102 | DB_1631610412546HSWK_0LNF_0012 | test_table_Oenl_102 |
| 103 | DB_1631610412546HSWK_0LNF_0012 | test_table_Oenl_103 |
| 104 | DB_1631610412546HSWK_0LNF_0013 | test_table_Oenl_104 |
| 105 | DB_1631610412546HSWK_0LNF_0013 | test_table_Oenl_105 |
| 106 | DB_1631610412546HSWK_0LNF_0013 | test_table_Oenl_106 |
| 107 | DB_1631610412546HSWK_0LNF_0013 | test_table_Oenl_107 |
| 108 | DB_1631610412546HSWK_0LNF_0013 | test_table_Oenl_108 |
| 109 | DB_1631610412546HSWK_0LNF_0013 | test_table_Oenl_109 |
| 110 | DB_1631610412546HSWK_0LNF_0013 | test_table_Oenl_110 |
| 111 | DB_1631610412546HSWK_0LNF_0013 | test_table_Oenl_111 |
| 112 | DB_1631610412546HSWK_0LNF_0014 | test_table_Oenl_112 |
| 113 | DB_1631610412546HSWK_0LNF_0014 | test_table_Oenl_113 |
| 114 | DB_1631610412546HSWK_0LNF_0014 | test_table_Oenl_114 |
| 115 | DB_1631610412546HSWK_0LNF_0014 | test_table_Oenl_115 |
| 116 | DB_1631610412546HSWK_0LNF_0014 | test_table_Oenl_116 |
| 117 | DB_1631610412546HSWK_0LNF_0014 | test_table_Oenl_117 |
| 118 | DB_1631610412546HSWK_0LNF_0014 | test_table_Oenl_118 |
| 119 | DB_1631610412546HSWK_0LNF_0014 | test_table_Oenl_119 |
| 120 | DB_1631610412546HSWK_0LNF_0015 | test_table_Oenl_120 |
| 121 | DB_1631610412546HSWK_0LNF_0015 | test_table_Oenl_121 |
| 122 | DB_1631610412546HSWK_0LNF_0015 | test_table_Oenl_122 |
| 123 | DB_1631610412546HSWK_0LNF_0015 | test_table_Oenl_123 |
| 124 | DB_1631610412546HSWK_0LNF_0015 | test_table_Oenl_124 |
| 125 | DB_1631610412546HSWK_0LNF_0015 | test_table_Oenl_125 |
| 126 | DB_1631610412546HSWK_0LNF_0015 | test_table_Oenl_126 |
| 127 | DB_1631610412546HSWK_0LNF_0015 | test_table_Oenl_127 |
+-----+------------------------------------+---------------------+
128 rows in set (0.28 sec)
分库分表键集合
查看分库分表键集合，分库键和分表键之间用逗号分割。如果最终结果有两个值，说明是既分库又分表的情形，第一个是分库键，第二个是分表键。如果结果只有一个值，说明是分库不分表的情形，该值是分库键。
mysql> show PARTITIONS from test_table;
+-------------+
| KEYS |
+-------------+
| TESTTABLE_ID |
+-------------+
1 row in set (0.07 sec)
广播表列表
查看广播表列表。
SHOW BROADCASTS;
+------+------------+
| ID | TABLE_NAME |
+------+------------+
| 0 | brd2 |
| 1 | brd_tbl |
+------+------------+
2 rows in set (0.01 sec)
SHOW DATASOURCES
查看底层存储信息，包含数据库名、数据库分组名、连接信息、用户名、底层存储类型、读写权重、连接池信息等。
SHOW DATASOURCES;
+------+----------------------------+------------------------------------------------+--------------------------------------------------+----------------------------------------------------------------------------------+-----------+-------+------+------+------+--------------+----------+--------------+---------------+----------------------------------------------+-------------+--------------+
| ID | SCHEMA | NAME | GROUP | URL | USER | TYPE | INIT | MIN | MAX | IDLE_TIMEOUT | MAX_WAIT | ACTIVE_COUNT | POOLING_COUNT | ATOM | READ_WEIGHT | WRITE_WEIGHT |
+------+----------------------------+------------------------------------------------+--------------------------------------------------+----------------------------------------------------------------------------------+-----------+-------+------+------+------+--------------+----------+--------------+---------------+----------------------------------------------+-------------+--------------+
| 0 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0000_iiab_1 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0000 | jnkinsea0 | xdb | 0 | 24 | 72 | 15 | 5000 | 0 | 1 | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0000_iiab | 10 | 10 |
| 1 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0001_iiab_2 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0001_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0001 | jnkinsea0 | xdb | 0 | 24 | 72 | 15 | 5000 | 0 | 1 | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0001_iiab | 10 | 10 |
| 2 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0002_iiab_3 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0002_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0002 | jnkinsea0 | xdb | 0 | 24 | 72 | 15 | 5000 | 0 | 1 | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0002_iiab | 10 | 10 |
| 3 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0003_iiab_4 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0003_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0003 | jnkinsea0 | xdb | 0 | 24 | 72 | 15 | 5000 | 0 | 1 | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0003_iiab | 10 | 10 |
| 4 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0004_iiab_5 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0004_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0004 | jnkinsea0 | xdb | 0 | 24 | 72 | 15 | 5000 | 0 | 1 | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0004_iiab | 10 | 10 |
| 5 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0005_iiab_6 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0005_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0005 | jnkinsea0 | xdb | 0 | 24 | 72 | 15 | 5000 | 0 | 1 | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0005_iiab | 10 | 10 |
| 6 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0006_iiab_7 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0006_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0006 | jnkinsea0 | xdb | 0 | 24 | 72 | 15 | 5000 | 0 | 1 | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0006_iiab | 10 | 10 |
| 7 | seq_test_1487767780814rgkk | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0007_iiab_8 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0007_RDS | jdbc:mysql://rds1ur80kcv8g3t6p3ol.mysql.rds.aliyuncs.com:3306/seq_test_wnjg_0007 | jnkinsea0 | xdb | 0 | 24 | 72 | 15 | 5000 | 0 | 1 | rds1ur80kcv8g3t6p3ol_seq_test_wnjg_0007_iiab | 10 | 10 |
+------+----------------------------+------------------------------------------------+--------------------------------------------------+----------------------------------------------------------------------------------+-----------+-------+------+------+------+--------------+----------+--------------+---------------+----------------------------------------------+-------------+--------------+
重要列详解：
- SCHEMA：数据库名；
- GROUP：数据库分组名。分组的目标是管理多组数据完全相同的数据库，比如通过 RDS（MySQL）进行数据复制后的主备数据库。主要用来解决读写分离、主备切换的问题；
- URL：底层RDS（MySQL）的连接信息；
- TYPE：底层存储类型。
- READ_WEIGHT ：读权重。在主实例的读压力比较大的时候，可以通过读写分离功能将读流量进行分流，减轻RDS主实例的压力。PolarDB-X会自动识别读写流量，引导写流量进入RDS主实例，读流量则按配置的权重流向所有RDS实例；
- WRITE_WEIGHT：写权重。
SHOW NODE
查看物理库的读写次数（历史累计数据）、读写权重（历史累计数据）。
SHOW NODE;
+------+--------------------------------------------------+-------------------+------------------+---------------------+--------------------+
| ID | NAME | MASTER_READ_COUNT | SLAVE_READ_COUNT | MASTER_READ_PERCENT | SLAVE_READ_PERCENT |
+------+--------------------------------------------------+-------------------+------------------+---------------------+--------------------+
| 0 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0000_RDS | 12 | 0 | 100% | 0% |
| 1 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0001_RDS | 0 | 0 | 0% | 0% |
| 2 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0002_RDS | 0 | 0 | 0% | 0% |
| 3 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0003_RDS | 0 | 0 | 0% | 0% |
| 4 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0004_RDS | 0 | 0 | 0% | 0% |
| 5 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0005_RDS | 0 | 0 | 0% | 0% |
| 6 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0006_RDS | 0 | 0 | 0% | 0% |
| 7 | SEQ_TEST_1487767780814RGKKSEQ_TEST_WNJG_0007_RDS | 0 | 0 | 0% | 0% |
+------+--------------------------------------------------+-------------------+------------------+---------------------+--------------------+
8 rows in set (0.01 sec)
重要列详解：
- MASTER_COUNT：RDS主实例处理的读写查询次数（历史累计数据）；
- SLAVE_COUNT：RDS备实例处理的只读查询次数（历史累计数据）；
- MASTER_PERCENT：RDS主实例处理的读写查询占比（注意该列显示的是累计的实际数据占比，并不是用户配置的百分比）；
- SLAVE_PERCENT：RDS备实例处理的读写查询占比（注意该列显示的是累计的实际数据占比，并不是用户配置的百分比）。
慢SQL相关
执行时间超过1秒的SQL语句是慢SQL，逻辑慢SQL是指应用发送到PolarDB-X的慢SQL。
语法
SHOW [FULL] SLOW [WHERE expr] [limit expr]
- SHOW SLOW：查看自PolarDB-X启动或者上次执行CLEAR SLOW以来最慢的100条逻辑慢SQL；
- SHOW FULL SLOW：查看实例启动以来记录的所有逻辑慢SQL（持久化到PolarDB-X的内置数据库中），该记录数默认为100条。
SHOW [FULL] PHYSICAL_SLOW [WHERE expr] [limit expr]
- SHOW PHYSICAL_SLOW：查看自PolarDB-X启动或者上次执行CLEAR SLOW 以来最慢的100条物理慢SQL（注意，这里记录的是最慢的100个，缓存在PolarDB-X系统中，当实例重启或者执行CLEAR SLOW时会丢失）;
- SHOW FULL PHYSICAL_SLOW：查看实例启动以来记录的所有物理慢SQL（持久化到PolarDB-X的内置数据库中）。该记录数默认为100条。
统计信息
SHOW [FULL] STATS
查看整体的统计信息，这些信息都是瞬时值。
SHOW STATS;
+------+---------+----------+-------------------+------------------+------------------------+--------------------+--------+------------+--------------+---------------+----------------+---------------+---------------+--------------+
| QPS | RDS_QPS | SLOW_QPS | PHYSICAL_SLOW_QPS | ERROR_PER_SECOND | MERGE_QUERY_PER_SECOND | ACTIVE_CONNECTIONS | RT(MS) | RDS_RT(MS) | NET_IN(KB/S) | NET_OUT(KB/S) | THREAD_RUNNING | DDL_JOB_COUNT | BACKFILL_ROWS | CHECKED_ROWS |
+------+---------+----------+-------------------+------------------+------------------------+--------------------+--------+------------+--------------+---------------+----------------+---------------+---------------+--------------+
| 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 1 | 0.00 | 0.00 | 0.00 | 0.00 | 1 | 0 | 0 | 0 |
+------+---------+----------+-------------------+------------------+------------------------+--------------------+--------+------------+--------------+---------------+----------------+---------------+---------------+--------------+
show full stats;
+------+---------+----------+-------------------+------------------+----------------------+------------------------+--------------------+------------------------------+--------+------------+--------------+---------------+----------------+----------------------+-----------------+----------------------------+-----------------------+------------------------------+-------------------------+--------------------------+---------------------+-------+---------+-------------+------------+
| QPS | RDS_QPS | SLOW_QPS | PHYSICAL_SLOW_QPS | ERROR_PER_SECOND | VIOLATION_PER_SECOND | MERGE_QUERY_PER_SECOND | ACTIVE_CONNECTIONS | CONNECTION_CREATE_PER_SECOND | RT(MS) | RDS_RT(MS) | NET_IN(KB/S) | NET_OUT(KB/S) | THREAD_RUNNING | HINT_USED_PER_SECOND | HINT_USED_COUNT | AGGREGATE_QUERY_PER_SECOND | AGGREGATE_QUERY_COUNT | TEMP_TABLE_CREATE_PER_SECOND | TEMP_TABLE_CREATE_COUNT | MULTI_DB_JOIN_PER_SECOND | MULTI_DB_JOIN_COUNT | CPU | FREEMEM | FULLGCCOUNT | FULLGCTIME |
+------+---------+----------+-------------------+------------------+----------------------+------------------------+--------------------+------------------------------+--------+------------+--------------+---------------+----------------+----------------------+-----------------+----------------------------+-----------------------+------------------------------+-------------------------+--------------------------+---------------------+-------+---------+-------------+------------+
| 1.63 | 1.68 | 0.03 | 0.03 | 0.02 | 0.00 | 0.00 | 6 | 0.01 | 157.13 | 51.14 | 134.33 | 1.21 | 1 | 0.00 | 54 | 0.00 | 663 | 0.00 | 512 | 0.00 | 516 | 0.09% | 6.96% | 76446 | 21326906 |
+------+---------+----------+-------------------+------------------+----------------------+------------------------+--------------------+------------------------------+--------+------------+--------------+---------------+----------------+----------------------+-----------------+----------------------------+-----------------------+------------------------------+-------------------------+--------------------------+---------------------+-------+---------+-------------+------------+
1 row in set (0.01 sec)
重要列说明：
- QPS：应用到PolarDB-X的QPS，通常称为逻辑QPS；
- RDS_QPS：PolarDB-X到RDS的QPS，通常称为物理QPS；
- ERROR_PER_SECOND：每秒的错误数，包含SQL语法错误，主键冲突，系统错误，连通性错误等各类错误总和；
- VIOLATION_PER_SECOND：每秒的主键或者唯一键冲突；
- MERGE_QUERY_PER_SECOND：通过分库分表，从多表中进行的查询；
- ACTIVE_CONNECTIONS：正在使用的连接；
- CONNECTION_CREATE_PER_SECOND：每秒创建的连接数；
- RT(MS)：应用到PolarDB-X的响应时间，通常称为逻辑RT（响应时间）；
- RDS_RT(MS)：PolarDB-X到RDS/MySQL的响应时间，通常称为物理RT；
- NET_IN(KB/S)：PolarDB-X收到的网络流量；
- NET_OUT(KB/S)：PolarDB-X输出的网络流量；
- THREAD_RUNNING：正在运行的线程数；
- HINT_USED_PER_SECOND：每秒带HINT的查询的数量；
- HINT_USED_COUNT：启动到现在带HINT的查询总量；
- AGGREGATE_QUERY_PER_SECOND：每秒聚合查询的频次；
- AGGREGATE_QUERY_COUNT：聚合查询总数（历史累计数据）；
- TEMP_TABLE_CREATE_PER_SECOND：每秒创建的临时表的数量；
- TEMP_TABLE_CREATE_COUNT：启动到现在创建的临时表总数量；
- MULTI_DB_JOIN_PER_SECOND：每秒跨库JOIN的数量；
- MULTI_DB_JOIN_COUNT：启动到现在跨库JOIN的总量。
SHOW DB STATUS
用于查看物理库容量/性能信息，所有返回值为实时信息。 容量信息通过MySQL系统表获得，与真实容量情况可能有差异。
SHOW DB STATUS;
+------+---------------------------+--------------------+-------------------+------------+--------+----------------+
| ID | NAME | CONNECTION_STRING | PHYSICAL_DB | SIZE_IN_MB | RATIO | THREAD_RUNNING |
+------+---------------------------+--------------------+-------------------+------------+--------+----------------+
| 1 | drds_db_1516187088365daui | 100.100.64.1:59077 | TOTAL | 13.109375 | 100% | 3 |
| 2 | drds_db_1516187088365daui | 100.100.64.1:59077 | drds_db_xzip_0000 | 1.578125 | 12.04% | |
| 3 | drds_db_1516187088365daui | 100.100.64.1:59077 | drds_db_xzip_0001 | 1.4375 | 10.97% | |
| 4 | drds_db_1516187088365daui | 100.100.64.1:59077 | drds_db_xzip_0002 | 1.4375 | 10.97% | |
| 5 | drds_db_1516187088365daui | 100.100.64.1:59077 | drds_db_xzip_0003 | 1.4375 | 10.97% | |
| 6 | drds_db_1516187088365daui | 100.100.64.1:59077 | drds_db_xzip_0004 | 1.734375 | 13.23% | |
| 7 | drds_db_1516187088365daui | 100.100.64.1:59077 | drds_db_xzip_0005 | 1.734375 | 13.23% | |
| 8 | drds_db_1516187088365daui | 100.100.64.1:59077 | drds_db_xzip_0006 | 2.015625 | 15.38% | |
| 9 | drds_db_1516187088365daui | 100.100.64.1:59077 | drds_db_xzip_0007 | 1.734375 | 13.23% | |
+------+---------------------------+--------------------+-------------------+------------+--------+----------------+
重要列说明：
- NAME：代表一个PolarDB-X DB，此处显示的是PolarDB-X内部标记，与PolarDB-X DB名称不同；
- CONNECTION_STRING：分库的连接信息；
- PHYSICAL_DB：分库名称，TOTAL行代表一个PolarDB-X DB中所有分库容量的总和；
- SIZE_IN_MB：分库中数据占用的空间，单位为MB；
- RATIO：单个分库数据量在当前PolarDB-X DB总数据量中的占比；
- THREAD_RUNNING：物理数据库实例当前正在执行的线程情况，含义与MySQL语句SHOW GLOBAL STATUS返回值的含义相同
SHOW TABLE STATUS
获取表的信息，该指令聚合了底层各个物理分表的数据。
SHOW TABLE STATUS;
+---------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+--------------------+----------+----------------+---------+
| NAME | ENGINE | VERSION | ROW_FORMAT | ROWS | AVG_ROW_LENGTH | DATA_LENGTH | MAX_DATA_LENGTH | INDEX_LENGTH | DATA_FREE | AUTO_INCREMENT | CREATE_TIME | UPDATE_TIME | CHECK_TIME | COLLATION | CHECKSUM | CREATE_OPTIONS | COMMENT |
+---------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+--------------------+----------+----------------+---------+
| sbtest1 | InnoDB | 10 | Dynamic | 0 | 0 | 1310720 | 0 | 0 | 0 | 0 | 2021-07-20 15:39:37 | NULL | NULL | utf8mb4_general_ci | NULL | | |
| t1 | InnoDB | 10 | Dynamic | 0 | 0 | 2621440 | 0 | 2621440 | 0 | 200000 | 2021-07-26 20:11:15 | NULL | NULL | utf8mb4_general_ci | NULL | | |
+---------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+--------------------+----------+----------------+---------+
重要列详解：
- NAME：表名称；
- ENGINE：表的存储引擎；
- VERSION：表的存储引擎的版本；
- ROW_FORMAT ：行格式，主要是Dynamic、Fixed、Compressed这三种格式。动态（Dynamic）行的行长度可变，例如VARCHAR或BLOB类型字段；固定（Fixed）行是指行长度不变，例如CHAR和INTEGER类型字段；
- ROWS：表中的行数；
- AVG_ROW_LENGTH：平均每行包括的字节数；
- DATA_LENGTH：整个表的数据量（单位：字节）；
- MAX_DATA_LENGTH：表可以容纳的最大数据量；
- INDEX_LENGTH：索引占用磁盘的空间大小 ；
- CREATE_TIME：表的创建时间；
- UPDATE_TIME：表的最近更新时间；
- COLLATION：表的默认字符集和字符排序规则；
- CREATE_OPTIONS：指表创建时的其他所有选项。
查看具体TABLE的状态可以使用 like 关键字
mysql> SHOW TABLE STATUS like test_table;
+------------+--------+---------+------------+---------+----------------+-------------+-----------------+--------------+-----------+----------------+-----------------------+-----------------------+------------+-----------------+----------+----------------+---------+
| NAME | ENGINE | VERSION | ROW_FORMAT | ROWS | AVG_ROW_LENGTH | DATA_LENGTH | MAX_DATA_LENGTH | INDEX_LENGTH | DATA_FREE | AUTO_INCREMENT | CREATE_TIME | UPDATE_TIME | CHECK_TIME | COLLATION | CHECKSUM | CREATE_OPTIONS | COMMENT |
+------------+--------+---------+------------+---------+----------------+-------------+-----------------+--------------+-----------+----------------+-----------------------+-----------------------+------------+-----------------+----------+----------------+---------+
| test_table | InnoDB | 10 | Dynamic | 5701365 | 2133 | 12166168576 | 0 | 1966866432 | 7340032 | 0 | 2022-01-05 04:42:18.0 | 2023-06-07 18:00:04.0 | NULL | utf8_general_ci | NULL | | 日志表 |
+------------+--------+---------+------------+---------+----------------+-------------+-----------------+--------------+-----------+----------------+-----------------------+-----------------------+------------+-----------------+----------+----------------+---------+
1 row in set (0.21 sec)
SHOW TABLE INFO [name]
获取各个分表的数据量信息。
SHOW TABLE INFO SBTEST1;
+----+--------------+-----------------+------------+
| ID | GROUP_NAME | TABLE_NAME | SIZE_IN_MB |
+----+--------------+-----------------+------------+
| 0 | test1_000000 | sbtest1_wo5k_00 | 0.01562500 |
| 1 | test1_000000 | sbtest1_wo5k_01 | 0.01562500 |
| 2 | test1_000005 | sbtest1_wo5k_10 | 0.01562500 |
| 3 | test1_000005 | sbtest1_wo5k_11 | 0.01562500 |
| 4 | test1_000010 | sbtest1_wo5k_20 | 0.01562500 |
| 5 | test1_000010 | sbtest1_wo5k_21 | 0.01562500 |
| 6 | test1_000015 | sbtest1_wo5k_30 | 0.01562500 |
| 7 | test1_000015 | sbtest1_wo5k_31 | 0.01562500 |
| 8 | test1_000020 | sbtest1_wo5k_40 | 0.01562500 |
| 9 | test1_000020 | sbtest1_wo5k_41 | 0.01562500 |
| 10 | test1_000025 | sbtest1_wo5k_50 | 0.01562500 |
| 11 | test1_000025 | sbtest1_wo5k_51 | 0.01562500 |
| 12 | test1_000030 | sbtest1_wo5k_60 | 0.01562500 |
| 13 | test1_000030 | sbtest1_wo5k_61 | 0.01562500 |
| 14 | test1_000035 | sbtest1_wo5k_70 | 0.01562500 |
| 15 | test1_000035 | sbtest1_wo5k_71 | 0.01562500 |
+----+--------------+-----------------+------------+
分析数据分布不均衡
当数据分布不均匀，大部分数据集中在一两个节点时，将导致节点负载过高、查询缓慢，甚至造成节点故障
分库级别的数据倾斜
show db status
索引触发全表代价
- rds索引命中范围超过80%
- drds索引命中范围超过60%
底层优化逻辑都会触发自动执行全表扫描的。