虽然基于少数表格生成报告，其中一些表格非常庞大（超过10亿条记录）而另一些表格非常小（100条记录），但需要17分钟。但是我在where子句中添加了一个条件，它开始运行1个多小时。
table1有10亿条记录，添加条件为＆＃34; line_ind（＆＃39; Y＆＃39;，＆＃39; *＆＃39;）＆＃34;。 问题是当CBO可以从连接的结果集进行搜索时，为什么CBO会进行全表扫描。有序提示似乎没有帮助，因此想知道如何使这个选择运行更快。
这是表格的记录计数
table1(a) 1,234,432,435
table2(b) 1,234,432,435
table3(c) 900
table4(d) 602,364,856
table5(e) 80
table6(f) 50
table7(g) 264,938,373
table8(h) 14,827
SELECT DISTINCT c_cd,
ci_nbr,
c.s_id1,
d.d_cd,
SUM (CASE WHEN (D_CD = 'MAILED') THEN 1 ELSE 0 END) AS MAILED
FROM table1 a
LEFT OUTER JOIN table2 b ON (a.o_id = b.o_id AND a.co_sid = b.co_sid)
INNER JOIN table3 c
ON c.c_sid = a.c_sid AND c.c_cd IN ('CC364', 'CC552')
INNER JOIN table4 c ON a.sc_sid = c.sc_sid
INNER JOIN table5 d ON d.d_SID = b.d_SID
INNER JOIN table6 e ON e.cc_sid = b.cc_sid
INNER JOIN table7 f ON f.ci_sid = b.ci_sid
INNER JOIN table8 g ON g.dt_sid = a.dt_sid
GROUP BY dt_cd,
c_nbr,
c.s_id1,
d.d_cd
where dt_cd in ('c6543-010114','c5653-010514') and line_ind in ('Y', '*') and c_nbr='728246'
解释计划
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | E-Rows |E-Bytes| Cost (%CPU)| E-Time | Pstart| Pstop | TQ |IN-OUT| PQ Distrib |
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 811 | 296K| 304K (3)| 01:11:02 | | | | | |
| 1 | PX COORDINATOR | | | | | | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10009 | 811 | 296K| 304K (3)| 01:11:02 | | | Q1,09 | P->S | QC (RAND) |
| 3 | HASH GROUP BY | | 811 | 296K| 304K (3)| 01:11:02 | | | Q1,09 | PCWP | |
| 4 | PX RECEIVE | | 811 | 296K| 304K (3)| 01:11:02 | | | Q1,09 | PCWP | |
| 5 | PX SEND HASH | :TQ10008 | 811 | 296K| 304K (3)| 01:11:02 | | | Q1,08 | P->P | HASH |
| 6 | HASH GROUP BY | | 811 | 296K| 304K (3)| 01:11:02 | | | Q1,08 | PCWP | |
|* 7 | HASH JOIN | | 811 | 296K| 304K (3)| 01:11:02 | | | Q1,08 | PCWP | |
| 8 | PX RECEIVE | | 802 | 278K| 277K (4)| 01:04:39 | | | Q1,08 | PCWP | |
| 9 | PX SEND BROADCAST | :TQ10007 | 802 | 278K| 277K (4)| 01:04:39 | | | Q1,07 | P->P | BROADCAST |
|* 10 | HASH JOIN | | 802 | 278K| 277K (4)| 01:04:39 | | | Q1,07 | PCWP | |
| 11 | PX RECEIVE | | 802 | 177K| 225K (4)| 00:52:44 | | | Q1,07 | PCWP | |
| 12 | PX SEND BROADCAST | :TQ10006 | 802 | 177K| 225K (4)| 00:52:44 | | | Q1,06 | P->P | BROADCAST |
|* 13 | HASH JOIN BUFFERED | | 802 | 177K| 225K (4)| 00:52:44 | | | Q1,06 | PCWP | |
| 14 | PX RECEIVE | | 96 | 4800 | 2 (0)| 00:00:01 | | | Q1,06 | PCWP | |
| 15 | PX SEND BROADCAST | :TQ10004 | 96 | 4800 | 2 (0)| 00:00:01 | | | Q1,04 | P->P | BROADCAST |
| 16 | PX BLOCK ITERATOR | | 96 | 4800 | 2 (0)| 00:00:01 | | | Q1,04 | PCWC | |
| 17 | TABLE ACCESS STORAGE FULL | TABLE5 | 96 | 4800 | 2 (0)| 00:00:01 | | | Q1,04 | PCWP | |
|* 18 | HASH JOIN | | 802 | 138K| 225K (4)| 00:52:44 | | | Q1,06 | PCWP | |
| 19 | BUFFER SORT | | | | | | | | Q1,06 | PCWC | |
| 20 | PX RECEIVE | | 51 | 561 | 5 (0)| 00:00:01 | | | Q1,06 | PCWP | |
| 21 | PX SEND HASH | :TQ10000 | 51 | 561 | 5 (0)| 00:00:01 | | | | S->P | HASH |
| 22 | TABLE ACCESS STORAGE FULL | TABLE6 | 51 | 561 | 5 (0)| 00:00:01 | | | | | |
| 23 | PX RECEIVE | | 802 | 130K| 225K (4)| 00:52:44 | | | Q1,06 | PCWP | |
| 24 | PX SEND HASH | :TQ10005 | 802 | 130K| 225K (4)| 00:52:44 | | | Q1,05 | P->P | HASH |
|* 25 | HASH JOIN | | 802 | 130K| 225K (4)| 00:52:44 | | | Q1,05 | PCWP | |
| 26 | PX RECEIVE | | 802 | 101K| 104K (5)| 00:24:25 | | | Q1,05 | PCWP | |
| 27 | PX SEND BROADCAST | :TQ10003 | 802 | 101K| 104K (5)| 00:24:25 | | | Q1,03 | P->P | BROADCAST |
|* 28 | HASH JOIN | | 802 | 101K| 104K (5)| 00:24:25 | | | Q1,03 | PCWP | |
| 29 | PX RECEIVE | | 2 | 24 | 17 (0)| 00:00:01 | | | Q1,03 | PCWP | |
| 30 | PX SEND BROADCAST | :TQ10001 | 2 | 24 | 17 (0)| 00:00:01 | | | Q1,01 | P->P | BROADCAST |
| 31 | PX BLOCK ITERATOR | | 2 | 24 | 17 (0)| 00:00:01 | | | Q1,01 | PCWC | |
|* 32 | TABLE ACCESS STORAGE FULL | TABLE3 | 2 | 24 | 17 (0)| 00:00:01 | | | Q1,01 | PCWP | |
|* 33 | HASH JOIN | | 68190 | 7857K| 104K (5)| 00:24:25 | | | Q1,03 | PCWP | |
| 34 | PX RECEIVE | | 2 | 34 | 276 (0)| 00:00:04 | | | Q1,03 | PCWP | |
| 35 | PX SEND BROADCAST | :TQ10002 | 2 | 34 | 276 (0)| 00:00:04 | | | Q1,02 | P->P | BROADCAST |
| 36 | PX BLOCK ITERATOR | | 2 | 34 | 276 (0)| 00:00:04 | | | Q1,02 | PCWC | |
|* 37 | TABLE ACCESS STORAGE FULL| TABLE8 | 2 | 34 | 276 (0)| 00:00:04 | | | Q1,02 | PCWP | |
| 38 | PX BLOCK ITERATOR | | 22M| 2177M| 104K (5)| 00:24:21 | 1 |1048575| Q1,03 | PCWC | |
|* 39 | TABLE ACCESS STORAGE FULL | TABLE1 | 22M| 2177M| 104K (5)| 00:24:21 | 1 |1048575| Q1,03 | PCWP | |
| 40 | PX BLOCK ITERATOR | | 969M| 32G| 121K (3)| 00:28:15 | 1 |1048575| Q1,05 | PCWC | |
|* 41 | TABLE ACCESS STORAGE FULL | TABLE2 | 969M| 32G| 121K (3)| 00:28:15 | 1 |1048575| Q1,05 | PCWP | |
| 42 | PX BLOCK ITERATOR | | 398M| 47G| 50955 (1)| 00:11:54 | | | Q1,07 | PCWC | |
| 43 | TABLE ACCESS STORAGE FULL | TABLE7 | 398M| 47G| 50955 (1)| 00:11:54 | | | Q1,07 | PCWP | |
| 44 | PX BLOCK ITERATOR | | 589M| 10G| 27170 (2)| 00:06:21 | 1 | 13 | Q1,08 | PCWC | |
| 45 | TABLE ACCESS STORAGE FULL | TABLE4 | 589M| 10G| 27170 (2)| 00:06:21 | 1 | 13 | Q1,08 | PCWP | |
答案 0 :(得分：0)
获取两个查询的10053条跟踪。这是Oracle的优化程序跟踪。你会明白为什么oracle会选择不同的计划，你不能错过它。
我认为此链接可以帮助您https://blogs.oracle.com/optimizer/entry/how_do_i_capture_a如果您愿意，可以谷歌获取10053上的其他教程。