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ç¼å表éç¨ lease æºå¶ä¿è¯ä»å个 TiDB Server ç¼å读åè·ä» TiKV 读åæ°æ®çä¸è´æ§ã
lease 代表ç§çº¦ï¼å¨å¯¹åºç lease å¨æå ï¼å°¤å ¶æ¯ WRITE æä½ï¼åªå¨ WRITE lease å å 许ï¼ä¸è´æ§éè¿ä»¥ä¸æ¹å¼ç¡®ä¿ï¼
- å¨ READ lease å ï¼ä¸å 许æ´æ¹æä½ï¼é£ä¹è·å READ lease å ç snapshot ä»ç¼åä¸è¯»åå¯ä»¥ä¿è¯ä¸è´æ§
- å¨ WRITE lease å ï¼
- 读å WRITE lease å ç snapshot ä» TiKV 读å
- åæä½ï¼äºå¡æ交ï¼ä¼æ£æ¥äºå¡ commit ts è¦æ±å¨ WRITE lease èå´å ï¼é£ä¹ä¿è¯äºæ§ç¼ååºäº snapshot ä¾ç¶ä¸è´
lease 说æ
mysql> select tb.TABLE_SCHEMA, tb.TABLE_NAME, cache.* from mysql.table_cache_meta as cache inner join information_schema.TABLES as tb on cache.tid = tb.TIDB_TABLE_ID;
+--------------+------------+-----+-----------+--------------------+--------------------+
| TABLE_SCHEMA | TABLE_NAME | tid | lock_type | lease | oldReadLease |
+--------------+------------+-----+-----------+--------------------+--------------------+
| sbtest1 | sbtest1 | 650 | WRITE | 432986910940987392 | 432986909630267392 |
+--------------+------------+-----+-----------+--------------------+--------------------+
1 row in set (0.00 sec)
table_cache_meta å个åä¿¡æ¯ï¼
- lock_typeï¼ç¼å表 lease çéç±»åï¼æ以ä¸å ç§ï¼
- NONEï¼æ²¡æéï¼ä¸è¬åªæå¨æ°å»ºçç¼å表ä¼ææ¤ç±»å
- READï¼è¯»éï¼å¨ lease å ï¼ä¸è½è¿è¡è¡¨æ´æ°æä½
- INTENDï¼åæä½çæåéï¼æ¢å å¼éç±»åãå¦æå½åéç±»å为读éæ¶ï¼éè¦è¿è¡åæä½ï¼æ·»å INTEND é»æ¢è¯»æä½å»¶é¿ leaseï¼ä½¿å¾åæä½è½é¡ºå©è·ååéãINTEND ç±»åæ¶ oldReadLease åçæï¼ä»£è¡¨ READ lease çæ¶é´ï¼å°æåå¼å§å 许åæä½ï¼lease å代表ææåé¢è·åç WRITE lease çæ¶é´ã
- WRITEï¼åéï¼å¨ lease å å¯ä»¥è¿è¡è¡¨æ´æ°æä½
- leaseï¼éå°ææ¶é´ï¼æ¯ tso ç±»åï¼ä»£è¡¨å½å lock_type çæææï¼å¦æ lease è¿æï¼éå°ä¼æ æ
- oldReadLeaseï¼åªæå INTEND éçæ¶åæä¼æ´æ°æ¤åï¼ä»£è¡¨è¯»æä½çç»ææ¶é´ï¼å°æåå¯ä»¥æ§è¡åæä½
读æä½
- ä¼å éæ© Point_GetãBatch_Point_Get ç®å
- å ¶æ¬¡ UnionScan ç®å
ç®åçæ¬ 6.0.0 对äºç®åçæ¥è¯¢ï¼å½å¯ä»¥éè¿ä¸»é®æè å¯ä¸ç´¢å¼æ£ç´¢æ°æ®æ¶åï¼æ¾ç¤ºèµ° Point_GetãBatch_Point_Get çæ§è¡è®¡åï¼æç¼åæ°æ®å¯ç¨ï¼ç´æ¥è¯»ç¼åï¼ã
å ¶ä»æ¥è¯¢ä¼çæ带æ UnionScan ç®åçæ§è¡è®¡åï¼é对ç¼å表çæç UnionScan ç®åï¼å°è£ äºä¸å±çæ§è¡é»è¾ï¼
- å¦æç¼åæ°æ®å¯ç¨ï¼éè¿ tidb server ç¼åæ°æ®æ¥è¯¢
- ç¼åæ°æ®ä¸å¯ç¨ï¼è®¿é® tikv æ¥è¯¢æ°æ®ï¼æ®éçå¿«ç §è¯»ï¼
éè¿ trace å½ä»¤æ¥ç UnionScan ç®åä¸æ¯èµ°çç¼åè¿æ¯å¸¸è§ tikv å¿«ç §æ¥ã
以 sbtest1 表åæµè¯ï¼è¡¨ç»æå¦ä¸(CACHED ON 说æå½åæ¯ç¼å表)ï¼
mysql> show create table sbtest1\G
*************************** 1. row ***************************
Table: sbtest1
Create Table: CREATE TABLE `sbtest1` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`k` int(11) NOT NULL DEFAULT '0',
`c` char(120) NOT NULL DEFAULT '',
`pad` char(60) NOT NULL DEFAULT '',
PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */,
KEY `k_1` (`k`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin AUTO_INCREMENT=469041 /* CACHED ON */
1 row in set (0.00 sec)
举ä¾1ï¼éè¿ä¸»é®æ¥è¯¢ï¼èµ° Point_Get ç®å
mysql> explain select * from sbtest1 where id = 10000;
+-------------+---------+------+---------------+---------------+
| id | estRows | task | access object | operator info |
+-------------+---------+------+---------------+---------------+
| Point_Get_1 | 1.00 | root | table:sbtest1 | handle:10000 |
+-------------+---------+------+---------------+---------------+
1 row in set (0.00 sec)
举ä¾2ï¼å ¶ä»ä¼èµ°ç¼å表é»è¾ï¼èµ° UnionScan ç®å
mysql> explain select * from sbtest1 where k = 10000;
+----------------------------------+---------+-----------+-----------------------------+---------------------------------------+
| id | estRows | task | access object | operator info |
+----------------------------------+---------+-----------+-----------------------------+---------------------------------------+
| UnionScan_6 | 1.97 | root | | eq(sbtest1.sbtest1.k, 10000) |
| ââIndexLookUp_12 | 1.97 | root | | |
| ââIndexRangeScan_10(Build) | 1.97 | cop[tikv] | table:sbtest1, index:k_1(k) | range:[10000,10000], keep order:false |
| ââTableRowIDScan_11(Probe) | 1.97 | cop[tikv] | table:sbtest1 | keep order:false |
+----------------------------------+---------+-----------+-----------------------------+---------------------------------------+
4 rows in set (0.00 sec)
举ä¾3ï¼çå¾ ç¼åè¿æï¼éè¿ trace å½ä»¤æ¥çå°æ§è¡ä» tikv æ¥è¯¢æ°æ®
mysql> trace select * from sbtest1 where k = 10000;
+-------------------------------------------------------------------------+-----------------+------------+
| operation | startTS | duration |
+-------------------------------------------------------------------------+-----------------+------------+
| trace | 13:06:40.722793 | 1.753585ms |
| ââsession.ExecuteStmt | 13:06:40.722798 | 314.799µs |
| â ââexecutor.Compile | 13:06:40.722806 | 177.778µs |
| â ââsession.runStmt | 13:06:40.723000 | 94.216µs |
| â ââUnionScanExec.Open | 13:06:40.723038 | 26.677µs |
| â ââbuildMemIndexLookUpReader | 13:06:40.723046 | 1.454µs |
| â ââmemIndexLookUpReader.getMemRows | 13:06:40.723054 | 4.785µs |
| ââ*executor.UnionScanExec.Next | 13:06:40.723122 | 1.39117ms |
| â ââ*executor.IndexLookUpExecutor.Next | 13:06:40.723125 | 1.367836ms |
| â â ââdistsql.Select | 13:06:40.723161 | 26.253µs |
| â â â ââregionRequest.SendReqCtx | 13:06:40.723237 | 698.852µs |
| â â â âârpcClient.SendRequest, region ID: 1372, type: Cop | 13:06:40.723256 | 634.524µs |
| â â ââdistsql.Select | 13:06:40.724022 | 15.073µs |
| â â â ââregionRequest.SendReqCtx | 13:06:40.724089 | 331.329µs |
| â â â âârpcClient.SendRequest, region ID: 1372, type: Cop | 13:06:40.724104 | 286.651µs |
| â â ââ*executor.TableReaderExecutor.Next | 13:06:40.724072 | 378.053µs |
| â â ââ*executor.TableReaderExecutor.Next | 13:06:40.724464 | 4.925µs |
| â ââ*executor.IndexLookUpExecutor.Next | 13:06:40.724508 | 835ns |
| ââ*executor.UnionScanExec.Next | 13:06:40.724521 | 7.952µs |
| ââ*executor.IndexLookUpExecutor.Next | 13:06:40.724525 | 474ns |
+-------------------------------------------------------------------------+-----------------+------------+
20 rows in set (0.01 sec)
举ä¾4ï¼ç¼åæ°æ®ææï¼éè¿ trace å½ä»¤æ¥çå°æ§è¡ä»ç¼åä¸æ¥è¯¢æ°æ®ï¼ä¸ç¨è®¿é® tikv.
mysql> trace select * from sbtest1 where k = 10000;
+-------------------------------------------------+-----------------+------------+
| operation | startTS | duration |
+-------------------------------------------------+-----------------+------------+
| trace | 13:06:43.415779 | 474.048µs |
| ââsession.ExecuteStmt | 13:06:43.415783 | 434.126µs |
| â ââexecutor.Compile | 13:06:43.415791 | 258.235µs |
| â ââsession.runStmt | 13:06:43.416065 | 126.674µs |
| â ââUnionScanExec.Open | 13:06:43.416105 | 55.186µs |
| â ââbuildMemIndexLookUpReader | 13:06:43.416109 | 1.624µs |
| â ââmemIndexLookUpReader.getMemRows | 13:06:43.416117 | 36.707µs |
| â ââmemTableReader.getMemRows | 13:06:43.416135 | 14.088µs |
| ââ*executor.UnionScanExec.Next | 13:06:43.416225 | 3.651µs |
| ââ*executor.UnionScanExec.Next | 13:06:43.416234 | 1.31µs |
+-------------------------------------------------+-----------------+------------+
10 rows in set (0.00 sec)
åæä½
å½æ°æ®éå¤§äº 64MB æ¶åï¼ç¦æ¢å¯¹è¡¨ç INSERTãUPDATEï¼å 许 DELETEã
对ç¼å表è¿è¡ DML æä½æ¶ï¼TiDB Server è¦è·å表ç WRITE leaseï¼ä»£è¡¨å¨è¿ä¸ªç§çº¦å ï¼å¯ä»¥è¿è¡è¡¨çåæä½ï¼å¦æè¦æ¥è¯¢çæ°æ®ç snapshot å¨ç§çº¦å ï¼é£å°±ä¸è½ç´æ¥ä½¿ç¨ç¼åçæ°æ®ï¼å 为 TiKV æ°æ®å¯è½å·²ç»æ´æ°ï¼é æç¼åæ°æ®ä¸ä¸è´ï¼è¿æ¶åéè¦ç´æ¥æ¥è¯¢ TiKV è·åä¸è´çæ°æ®ã
å¨ WRITE lease å ï¼è¯»æ¥è¯¢éå为è·æ®é表ä¸æ ·çä» TiKV 读åã
ä½¿ç¨ sysbench åæµ select æ¥è¯¢è¿ç¨ä¸ï¼å¯¹è¡¨æ§è¡ä¸ä¸ª dml æä½ï¼è¡¨ç WRITE lease æé´ï¼ç¼å失æï¼ä» tikv æ¥è¯¢æ°æ®ï¼è¡¨ç°åºåæµ tps åºç°ä¸éï¼latency åé¿çæ æ¯ï¼å½ dml æ§è¡ç»æï¼è¡¨éæ°åå° READ lease æ¶ï¼tps åååå°ä¹åçæ°å¼ã
[ 16s ] thds: 32 tps: 63156.73 qps: 63156.73 (r/w/o: 63156.73/0.00/0.00) lat (ms,95%): 0.78 err/s: 0.00 reconn/s: 0.00
[ 17s ] thds: 32 tps: 63100.18 qps: 63100.18 (r/w/o: 63100.18/0.00/0.00) lat (ms,95%): 0.78 err/s: 0.00 reconn/s: 0.00
[ 18s ] thds: 32 tps: 62388.72 qps: 62388.72 (r/w/o: 62388.72/0.00/0.00) lat (ms,95%): 0.80 err/s: 0.00 reconn/s: 0.00
[ 19s ] thds: 32 tps: 62373.22 qps: 62373.22 (r/w/o: 62373.22/0.00/0.00) lat (ms,95%): 0.81 err/s: 0.00 reconn/s: 0.00
[ 20s ] thds: 32 tps: 32795.91 qps: 32795.91 (r/w/o: 32795.91/0.00/0.00) lat (ms,95%): 1.86 err/s: 0.00 reconn/s: 0.00
[ 21s ] thds: 32 tps: 31120.99 qps: 31120.99 (r/w/o: 31120.99/0.00/0.00) lat (ms,95%): 1.89 err/s: 0.00 reconn/s: 0.00
[ 22s ] thds: 32 tps: 31001.04 qps: 31001.04 (r/w/o: 31001.04/0.00/0.00) lat (ms,95%): 1.89 err/s: 0.00 reconn/s: 0.00
[ 23s ] thds: 32 tps: 30879.05 qps: 30879.05 (r/w/o: 30879.05/0.00/0.00) lat (ms,95%): 1.96 err/s: 0.00 reconn/s: 0.00
[ 24s ] thds: 32 tps: 28217.93 qps: 28217.93 (r/w/o: 28217.93/0.00/0.00) lat (ms,95%): 2.07 err/s: 0.00 reconn/s: 0.00
[ 25s ] thds: 32 tps: 52939.06 qps: 52939.06 (r/w/o: 52939.06/0.00/0.00) lat (ms,95%): 1.14 err/s: 0.00 reconn/s: 0.00
[ 26s ] thds: 32 tps: 61600.98 qps: 61600.98 (r/w/o: 61600.98/0.00/0.00) lat (ms,95%): 0.81 err/s: 0.00 reconn/s: 0.00
[ 27s ] thds: 32 tps: 60956.91 qps: 60956.91 (r/w/o: 60956.91/0.00/0.00) lat (ms,95%): 0.83 err/s: 0.00 reconn/s: 0.00
[ 28s ] thds: 32 tps: 63911.26 qps: 63911.26 (r/w/o: 63911.26/0.00/0.00) lat (ms,95%): 0.78 err/s: 0.00 reconn/s: 0.00
[ 29s ] thds: 32 tps: 63052.79 qps: 63052.79 (r/w/o: 63052.79/0.00/0.00) lat (ms,95%): 0.78 err/s: 0.00 reconn/s: 0.00
ç±äºè¦å è·å WRITE leaseï¼ä¹å°±æ¯å¨ DML æ¶åï¼è¦çå¾ è·å lease åæè½è¿è¡äºå¡æ交ï¼æ以对äºç¼å表ï¼æ§è¡æ´æ¹å¯è½èæ¶è¾é¿ï¼æ£å¸¸çå¾ è·å lease çæ¶é´å¨ 0 ~ tidb_table_cache_lease çèå´ï¼ä¹å°±æ¯ INTEND lock çæææ¶é´ï¼çå¾ READ lease è¿æã
å¨ DML äºå¡ commit é¶æ®µå°è¯è·å WRITE leaseï¼ä¹å°±æ¯å¨æ交æ¶å»¶æ¶è¾å¤§ã
mysql> begin;
Query OK, 0 rows affected (0.00 sec)
mysql> delete from sbtest1 where id = 100;
Query OK, 1 row affected (0.00 sec)
mysql> commit;
Query OK, 0 rows affected (5.32 sec)
è¿é commit è¯å¥èæ¶ 5.32 ç§ï¼å 为å¨æ交é¶æ®µçå¾ è·å WRITE lease èæ¶è¾é¿ã
ååæµè¯
ä½¿ç¨ sysbench 对ç¼å表å表è¿è¡ç¨³å®æ§ååæµè¯ï¼åæµçº¿ç¨æ°åºå®ä¸º 32ï¼æ¯ä¸ªåæµè¡¨çè¡æ°ä¼åï¼ä» 50 ~ 204800 éå¢ï¼è¡¨ç»æå¦ä¸ï¼
mysql> show create table sbtest1\G
*************************** 1. row ***************************
Table: sbtest1
Create Table: CREATE TABLE `sbtest1` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`k` int(11) NOT NULL DEFAULT '0',
`c` char(120) NOT NULL DEFAULT '',
`pad` char(60) NOT NULL DEFAULT '',
PRIMARY KEY (`id`) /*T![clustered_index] CLUSTERED */,
KEY `k_1` (`k`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin AUTO_INCREMENT=106519 /* CACHED ON */
1 row in set (0.00 sec)
sysbench åæµè¯å¥å¦ä¸ï¼
SELECT c FROM sbtest1 WHERE k = sb_rand(1, oltp_table_size);
åæµç»æ(count æ¯è¡¨çæ°æ®è¡æ°ï¼ï¼
count tps qps latency
50 54516.24 54516.24 1.27ms
100 54934.17 54934.17 1.25ms
200 54061.46 54061.46 1.30ms
400 53859.76 53859.76 1.32ms
800 53083.76 53083.76 1.34ms
1600 53464.69 53464.69 1.34ms
3200 53157.89 53157.89 1.32ms
6400 53531.27 53531.27 1.27ms
12800 56076.71 56076.71 1.06ms
25600 58441.74 58441.74 0.95ms
51200 59734.40 59734.40 0.87ms
102400 61787.46 61787.46 0.78ms
204800 64656.75 64656.75 0.72ms
åæµè¿ç¨ä¸é´æ°æ®ï¼
[ 50s ] thds: 32 tps: 62284.70 qps: 62284.70 (r/w/o: 62284.70/0.00/0.00) lat (ms,95%): 0.77 err/s: 0.00 reconn/s: 0.00
[ 51s ] thds: 32 tps: 62437.31 qps: 62437.31 (r/w/o: 62437.31/0.00/0.00) lat (ms,95%): 0.78 err/s: 0.00 reconn/s: 0.00
[ 52s ] thds: 32 tps: 62268.66 qps: 62268.66 (r/w/o: 62268.66/0.00/0.00) lat (ms,95%): 0.77 err/s: 0.00 reconn/s: 0.00
[ 53s ] thds: 32 tps: 62325.43 qps: 62325.43 (r/w/o: 62325.43/0.00/0.00) lat (ms,95%): 0.78 err/s: 0.00 reconn/s: 0.00
[ 54s ] thds: 32 tps: 62224.41 qps: 62224.41 (r/w/o: 62224.41/0.00/0.00) lat (ms,95%): 0.81 err/s: 0.00 reconn/s: 0.00
[ 55s ] thds: 32 tps: 62159.53 qps: 62159.53 (r/w/o: 62159.53/0.00/0.00) lat (ms,95%): 0.81 err/s: 0.00 reconn/s: 0.00
[ 56s ] thds: 32 tps: 61839.63 qps: 61839.63 (r/w/o: 61839.63/0.00/0.00) lat (ms,95%): 0.81 err/s: 0.00 reconn/s: 0.00
[ 57s ] thds: 32 tps: 59084.72 qps: 59084.72 (r/w/o: 59084.72/0.00/0.00) lat (ms,95%): 0.81 err/s: 0.00 reconn/s: 0.00
[ 58s ] thds: 32 tps: 62009.57 qps: 62009.57 (r/w/o: 62009.57/0.00/0.00) lat (ms,95%): 0.81 err/s: 0.00 reconn/s: 0.00
[ 59s ] thds: 32 tps: 60203.24 qps: 60203.24 (r/w/o: 60203.24/0.00/0.00) lat (ms,95%): 0.77 err/s: 0.00 reconn/s: 0.00
[ 60s ] thds: 32 tps: 62814.70 qps: 62814.70 (r/w/o: 62814.70/0.00/0.00) lat (ms,95%): 0.78 err/s: 0.00 reconn/s: 0.00
[ 61s ] thds: 32 tps: 59874.28 qps: 59874.28 (r/w/o: 59874.28/0.00/0.00) lat (ms,95%): 0.80 err/s: 0.00 reconn/s: 0.00
[ 62s ] thds: 32 tps: 62260.65 qps: 62260.65 (r/w/o: 62260.65/0.00/0.00) lat (ms,95%): 0.80 err/s: 0.00 reconn/s: 0.00
[ 63s ] thds: 32 tps: 61401.04 qps: 61401.04 (r/w/o: 61401.04/0.00/0.00) lat (ms,95%): 0.87 err/s: 0.00 reconn/s: 0.00
[ 64s ] thds: 32 tps: 62067.33 qps: 62067.33 (r/w/o: 62067.33/0.00/0.00) lat (ms,95%): 0.78 err/s: 0.00 reconn/s: 0.00
[ 65s ] thds: 32 tps: 62575.07 qps: 62575.07 (r/w/o: 62575.07/0.00/0.00) lat (ms,95%): 0.80 err/s: 0.00 reconn/s: 0.00
[ 66s ] thds: 32 tps: 62451.52 qps: 62451.52 (r/w/o: 62451.52/0.00/0.00) lat (ms,95%): 0.78 err/s: 0.00 reconn/s: 0.00
[ 67s ] thds: 32 tps: 62328.75 qps: 62328.75 (r/w/o: 62328.75/0.00/0.00) lat (ms,95%): 0.80 err/s: 0.00 reconn/s: 0.00
[ 68s ] thds: 32 tps: 62482.39 qps: 62482.39 (r/w/o: 62482.39/0.00/0.00) lat (ms,95%): 0.84 err/s: 0.00 reconn/s: 0.00
[ 69s ] thds: 32 tps: 62094.58 qps: 62094.58 (r/w/o: 62094.58/0.00/0.00) lat (ms,95%): 0.81 err/s: 0.00 reconn/s:
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- ç¼å表éç¨äºè¡¨æ°æ®éå°ãæ¥è¯¢å¤ãåæå°æ DML çåºæ¯
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- å½æ DML æ¶ï¼ç¼å读åéå°æ®éç TiKV snapshot 读ï¼è¿æ¶å读 Latency å¢å¤§ãTPS éä½
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- å¦æç¼åå è½½è¾æ ¢ï¼å¯ä»¥éå½å»¶é¿ tidb_table_cache_lease å¼ï¼å¢å¤§å¯è½ä¼å¯¼è´ DML äºå¡æ交é»å¡æ´ä¹ ï¼å¯¹äºæå° DML çç¼å表åºæ¯ï¼å»ºè®®éå½è°å¤§ tidb_table_cache_lease å¼