Exadata上的Oracle数据库。更新运行数小时，并行提示为'；行不通
我们有两个巨大的表，试图更新大约6000万条记录。以前它只需要30分钟就可以更新，现在它需要花费数小时n小时，甚至不超过数据增长的20%。这里有更多的信息。我看到在“单元单块物理读取”“PX Deq:Table Q Normal”事件上有很多等待。我不明白为什么并行提示不起作用。这就是单元单块物理读取的原因吗？或者有没有其他原因导致性能下降，有什么想法 ? 为什么要通过去掉“WHERE EXISTS”子句来提高性能 表1（A）尺寸316 GB 记录计数4563654 表2（B）7GB 记录计数31934956Exadata上的Oracle数据库。更新运行数小时，并行提示为'；行不通,oracle,performance,parallel-processing,updates,exadata,Oracle,Performance,Parallel Processing,Updates,Exadata,我们有两个巨大的表，试图更新大约6000万条记录。以前它只需要30分钟就可以更新，现在它需要花费数小时n小时，甚至不超过数据增长的20%。这里有更多的信息。我看到在“单元单块物理读取”“PX Deq:Table Q Normal”事件上有很多等待。我不明白为什么并行提示不起作用。这就是单元单块物理读取的原因吗？或者有没有其他原因导致性能下降，有什么想法 ? 为什么要通过去掉“WHERE EXISTS”子句来提高性能 表1（A）尺寸316 GB 记录计数4563654 表2（B）7GB 记录计数3
UPDATE /*+ parallel (a, 8) */
table1 a
SET (c_age,
c_age_de,
wa_only_ind) =
(SELECT c_age,
c_age_de,
wa_only_ind
FROM table2 b
WHERE B.ip = A.ip
AND a.c_age IS NULL
AND b.o_type IN ('TYPE12', 'TYPE14'))
WHERE EXISTS
(SELECT 1
FROM table2 b2
WHERE b2.ip = a.ip
AND a.c_age IS NULL
AND b2.o_type IN ('TYPE12', 'TYPE14'));
----------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | E-Rows |E-Bytes| Cost (%CPU)| E-Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib |
----------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | UPDATE STATEMENT | | 17M| 9599M| 5076M (20)|999:59:59 | | | | | |
| 1 | UPDATE | TABLE1 | | | | | | | | | |
| 2 | PX COORDINATOR | | | | | | | | | | |
| 3 | PX SEND QC (RANDOM) | :TQ10002 | 17M| 9599M| 1069K (1)| 04:09:40 | | | Q1,02 | P->S | QC (RAND) |
|* 4 | HASH JOIN RIGHT SEMI BUFFERED| | 17M| 9599M| 1069K (1)| 04:09:40 | | | Q1,02 | PCWP | |
| 5 | PX RECEIVE | | 29M| 476M| 23984 (2)| 00:05:36 | | | Q1,02 | PCWP | |
| 6 | PX SEND HASH | :TQ10000 | 29M| 476M| 23984 (2)| 00:05:36 | | | Q1,00 | P->P | HASH |
| 7 | PX BLOCK ITERATOR | | 29M| 476M| 23984 (2)| 00:05:36 | | | Q1,00 | PCWC | |
|* 8 | TABLE ACCESS STORAGE FULL| TABLE2 | 29M| 476M| 23984 (2)| 00:05:36 | | | Q1,00 | PCWP | |
| 9 | PX RECEIVE | | 57M| 30G| 1045K (1)| 04:04:04 | | | Q1,02 | PCWP | |
| 10 | PX SEND HASH | :TQ10001 | 57M| 30G| 1045K (1)| 04:04:04 | | | Q1,01 | P->P | HASH |
| 11 | PX BLOCK ITERATOR | | 57M| 30G| 1045K (1)| 04:04:04 | 1 | 3 | Q1,01 | PCWC | |
|* 12 | TABLE ACCESS STORAGE FULL| TABLE1 | 57M| 30G| 1045K (1)| 04:04:04 | 1 | 6 | Q1,01 | PCWP | |
|* 13 | FILTER | | | | | | | | | | |
|* 14 | TABLE ACCESS BY INDEX ROWID | TABLE2 | 1 | 210 | 4 (0)| 00:00:01 | | | | | |
|* 15 | INDEX RANGE SCAN | TABLE2_IDX1 | 1 | | 3 (0)| 00:00:01 | | | | | |
----------------------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
4 - access("B2"."IP"="A"."IP")
8 - storage("B2"."O_TYPE"='TYPE1' OR "B2"."O_TYPE"='TYPE12')
filter("B2"."O_TYPE"='TYPE1' OR "B2"."O_TYPE"='TYPE12')
12 - storage("A"."C_AGE" IS NULL)
filter("A"."C_AGE" IS NULL)
13 - filter(:B1 IS NULL)
14 - filter("B"."O_TYPE"='TYPE1' OR "B"."O_TYPE"='TYPE12')
15 - access("B"."IP"=:B1)
SQL_ID dd0ah20057j37
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | E-Rows |E-Bytes| Cost (%CPU)| E-Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib | OMem | 1Mem | O/1/M |
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | UPDATE STATEMENT | | | | 43T(100)| | | | | | | | | |
| 1 | UPDATE | TABLE1 | | | | | | | | | | | | |
| 2 | PX COORDINATOR | | | | | | | | | | | | | |
| 3 | PX SEND QC (RANDOM) | :TQ10002 | 57M| 31G| 65326 (3)| 00:14:16 | | | Q1,02 | P->S | QC (RAND) | | | |
|* 4 | HASH JOIN RIGHT SEMI BUFFERED| | 57M| 31G| 65326 (3)| 00:14:16 | | | Q1,02 | PCWP | | 1537M| 25M| 2/0/0|
| 5 | PX RECEIVE | | 32M| 550M| 2190 (20)| 00:00:29 | | | Q1,02 | PCWP | | | | |
| 6 | PX SEND HASH | :TQ10000 | 32M| 550M| 2190 (20)| 00:00:29 | | | Q1,00 | P->P | HASH | | | |
| 7 | PX BLOCK ITERATOR | | 32M| 550M| 2190 (20)| 00:00:29 | | | Q1,00 | PCWC | | | | |
|* 8 | TABLE ACCESS STORAGE FULL| TABLE2 P1 | 32M| 550M| 2190 (20)| 00:00:29 | | | Q1,00 | PCWP | | 1025K| 1025K| 2/0/0|
| 9 | PX RECEIVE | | 57M| 30G| 63100 (2)| 00:13:47 | | | Q1,02 | PCWP | | | | |
| 10 | PX SEND HASH | :TQ10001 | 57M| 30G| 63100 (2)| 00:13:47 | | | Q1,01 | P->P | HASH | | | |
| 11 | PX BLOCK ITERATOR | | 57M| 30G| 63100 (2)| 00:13:47 | 1 | 3 | Q1,01 | PCWC | | | | |
|* 12 | TABLE ACCESS STORAGE FULL| TABLE1 | 57M| 30G| 63100 (2)| 00:13:47 | 1 | 6 | Q1,01 | PCWP | | 1025K| 1025K| 2/0/0|
|* 13 | FILTER | | | | | | | | | | | | | |
|* 14 | TABLE ACCESS BY INDEX ROWID | TABLE2 | 320K| 113M| 12787 (1)| 00:02:48 | | | | | | | | |
|* 15 | INDEX RANGE SCAN | TABLE2_IDX1 | 128K| | 4 (25)| 00:00:01 | | | | | | 1025K| 1025K| |
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
4 - access("U2"."IP"="I"."IP")
8 - storage(:Z>=:Z AND :Z<=:Z AND (("U2"."OPERATION_TYPE"='TYPE1' OR "U2"."OPERATION_TYPE"='TYPE12')))
filter(("U2"."OPERATION_TYPE"='TYPE1' OR "U2"."OPERATION_TYPE"='TYPE12'))
12 - storage(:Z>=:Z AND :Z<=:Z AND "I"."AGE" IS NULL)
filter("I"."AGE" IS NULL)
13 - filter(:B1 IS NULL)
14 - filter(("U"."OPERATION_TYPE"='TYPE1' OR "U"."OPERATION_TYPE"='TYPE12'))
15 - access("U"."IP"=:B1)
Plan hash value: 1669240984
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | E-Rows |E-Bytes|E-Temp | Cost (%CPU)| E-Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib | OMem | 1Mem | O/1/M |
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | MERGE STATEMENT | | | | | 374K(100)| | | | | | | | | |
| 1 | MERGE | TABLE1 | | | | | | | | | | | | | |
| 2 | PX COORDINATOR | | | | | | | | | | | | | | |
| 3 | PX SEND QC (RANDOM) | :TQ10002 | 413M| 574G| | 374K (2)| 01:21:50 | | | Q1,02 | P->S | QC (RAND) | | | |
| 4 | VIEW | | | | | | | | | Q1,02 | PCWP | | | | |
|* 5 | HASH JOIN BUFFERED | | 413M| 574G| 3583M| 374K (2)| 01:21:50 | | | Q1,02 | PCWP | | 2047M| 100M| |
| 6 | PX RECEIVE | | 32M| 27G| | 2199 (20)| 00:00:29 | | | Q1,02 | PCWP | | | | |
| 7 | PX SEND HASH | :TQ10000 | 32M| 27G| | 2199 (20)| 00:00:29 | | | Q1,00 | P->P | HASH | | | |
| 8 | PX BLOCK ITERATOR | | 32M| 27G| | 2199 (20)| 00:00:29 | | | Q1,00 | PCWC | | | | |
|* 9 | TABLE ACCESS STORAGE FULL| TABLE2 | 32M| 27G| | 2199 (20)| 00:00:29 | | | Q1,00 | PCWP | | 1025K| 1025K| 2/0/0|
| 10 | PX RECEIVE | | 413M| 218G| | 67413 (9)| 00:14:44 | | | Q1,02 | PCWP | | | | |
| 11 | PX SEND HASH | :TQ10001 | 413M| 218G| | 67413 (9)| 00:14:44 | | | Q1,01 | P->P | HASH | | | |
| 12 | PX BLOCK ITERATOR | | 413M| 218G| | 67413 (9)| 00:14:44 | 1 | 3 | Q1,01 | PCWC | | | | |
|* 13 | TABLE ACCESS STORAGE FULL| TABLE1 | 413M| 218G| | 67413 (9)| 00:14:44 | 1 | 6 | Q1,01 | PCWP | | 1025K| 1025K| 2/0/0|
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
5 - access("I"."IP"="U"."IP")
9 - storage(:Z>=:Z AND :Z<=:Z AND (("U"."OPERATION_TYPE"='TYPE1' OR "U"."OPERATION_TYPE"='TYPE12')))
filter(("U"."OPERATION_TYPE"='TYPE1' OR "U"."OPERATION_TYPE"='TYPE12'))
13 - storage(:Z>=:Z AND :Z<=:Z)
----------------------------------------------------------------------------------------------------------------------------------------------------------
|Id |操作|名称| E行| E字节|成本（%CPU）| E时间| Pstart | Pstop | TQ |输入输出| PQ发行版|
----------------------------------------------------------------------------------------------------------------------------------------------------------
|0 |更新语句| 17M | 9599M | 5076M（20）| 999:59:59 | | | | ||
|1 |更新|表1 | | | | | | | ||
|2 | PX协调员| | | | | | | | ||
|3 | PX发送QC（随机）|：TQ10002 | 17M | 9599M | 1069K（1）| 04:09:40 | | | Q1,02 | P->S | QC（兰德）|
|*4 |哈希连接右半缓冲| 17M | 9599M | 1069K（1）| 04:09:40 | | | Q1,02 | PCWP ||
|5 | PX接收| 29M | 476M | 23984（2）| 00:05:36 | Q1,02 | PCWP ||
|6 | PX发送散列：TQ10000 | 29M | 476M | 23984（2）| 00:05:36 | | | Q1,00 | P->P |散列|
|7 | PX块迭代器| 29M | 476M | 23984（2）| 00:05:36 | | | Q1,00 | PCWC ||
|*8 |表访问存储已满|表2 | 29M | 476M | 23984（2）| 00:05:36 | | Q1,00 | PCWP ||
|9 | PX接收| 57M | 30G | 1045K（1）| 04:04:04 | Q1,02 | PCWP ||
|10 | PX发送散列|：TQ10001 | 57M | 30G | 1045K（1）| 04:04:04 | | | Q1,01 | P->P |散列|
|11 | PX块迭代器| 57M | 30G | 1045K（1）| 04:04:04 | 1 | 3 | Q1,01 | PCWC ||
|*12 |表访问存储已满|表1 | 57M | 30G | 1045K（1）| 04:04:04 | 1 | 6 | Q1,01 | PCWP ||
|*13 |过滤器| | | | | | | | ||
|*14 |按索引ROWID访问表|表2 | 1 | 210 | 4（0）| 00:00:01 | | | ||
|*15 |索引范围扫描|表2 | IDX1 | 1 | | 3（0）| 00:00:01 | | | ||
----------------------------------------------------------------------------------------------------------------------------------------------------------
谓词信息（由操作id标识）：
---------------------------------------------------
4-访问（“B2”“IP”=“A”“IP”）
8-存储（“B2”“O_类型”=“TYPE1”或“B2”“O_类型”=“TYPE12”）
过滤器（“B2”。“O_类型”=“TYPE1”或“B2”。“O_类型”=“TYPE12”）
12-存储（“A”。“C_AGE”为空）
过滤器（“A.“C_AGE”为空）
13-过滤器（：B1为空）
14-过滤器（“B”。“O_类型”='TYPE1'或“B”。“O_类型”='TYPE12'）
15-访问（“B”。“IP”=：B1）
SQL_ID dd0ah20057j37
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|Id |操作|名称| E行| E字节|成本（%CPU）| E时间| Pstart | Pstop | TQ |输入输出| PQ分发| OMem | 1Mem | O/1/M|
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|0 |更新语句| | | | | | | | | | | ||
|1 |更新|表1 | | | | | | | | ||
|2 | PX协调员| | | | | | | | | | ||
|3 | PX发送质控（随机）|：TQ10002 | 57M | 31G | 65326（3）| 00:14:16 | | | Q1,02 | P->S |质控（兰德）||
|*4 |散列连接右半缓冲| 57M | 31G | 65326（3）| 00:14:16 | | | | Q1,02 | PCWP | 1537M | 25M | 2/0/0|
|5 | PX接收|
drop table test1 purge;
create table test1(a number not null, b number);
insert into test1 select level, 1 from dual connect by level <= 100000;
begin
dbms_stats.gather_table_stats(user, 'TEST1');
end;
/
alter session disable parallel dml;
explain plan for update /*+ parallel(test1, 8) */ test1 set a = 1 where b <= 1000;
select * from table(dbms_xplan.display);
---------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | TQ |IN-OUT| PQ Distrib |
---------------------------------------------------------------------------------------------------------------
| 0 | UPDATE STATEMENT | | 100K| 781K| 11 (10)| 00:00:01 | | | |
| 1 | UPDATE | TEST1 | | | | | | | |
| 2 | PX COORDINATOR | | | | | | | | |
...
rollback;
alter session enable parallel dml;
explain plan for update /*+ parallel(test1, 8) */ test1 set a = 1 where b <= 1000;
select * from table(dbms_xplan.display);
---------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | TQ |IN-OUT| PQ Distrib |
---------------------------------------------------------------------------------------------------------------
| 0 | UPDATE STATEMENT | | 100K| 781K| 11 (10)| 00:00:01 | | | |
| 1 | PX COORDINATOR | | | | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10000 | 100K| 781K| 11 (10)| 00:00:01 | Q1,00 | P->S | QC (RAND) |
| 3 | UPDATE | TEST1 | | | | | Q1,00 | PCWP | |
...