解析一个通过添加本地分区索引提高SQL性能的案例
今天接到同事求助，说有一个select query，在Oracle上要跑一分多钟，他希望能在5s内出结果，以下就是解决这个问题的方法，需要的朋友可以参考下 该sql如下： 复制代码 代码如下: Select /*+ parallel(src, 8) */ distinct src.systemname as systemname ,
今天接到同事求助，说有一个select query，在Oracle上要跑一分多钟，他希望能在5s内出结果，以下就是解决这个问题的方法，需要的朋友可以参考下
该sql如下：
复制代码 代码如下:
Select /*+ parallel(src, 8) */ distinct
src.systemname as systemname
, src.databasename as databasename
, src.tablename as tablename
, src.username as username
from meta_dbql_table_usage_exp_hst src
inner join DR_QRY_LOG_EXP_HST rl on
src.acctstringdate = rl.acctstringdate
and src.queryid = rl.queryid
And Src.Systemname = Rl.Systemname
and src.acctstringdate > sysdate - 30
And Rl.Acctstringdate > Sysdate - 30
inner join meta_dr_qry_log_tgt_all_hst tgt on
upper(tgt.systemname) = upper('MOZART')
And Upper(tgt.Databasename) = Upper('GDW_TABLES')
And Upper(tgt.Tablename) = Upper('SSA_SLNG_LSTG_MTRC_SD')
AND src.acctstringdate = tgt.acctstringdate
and rl.statement_id = tgt.statement_id
and rl.systemname = tgt.systemname
And Tgt.Acctstringdate > Sysdate - 30
And Not(
Upper(Tgt.Systemname)=Upper(src.systemname)
And
Upper(Tgt.Databasename) = Upper(Src.Databasename)
And
Upper(Tgt.Tablename) = Upper(Src.Tablename)
)
And tgt.Systemname is not null
And tgt.Databasename Is Not Null
And tgt.tablename is not null
SQL的简单分析
总 得来看，这个SQL就是三个表 (meta_dbql_table_usage_exp_hst，DR_QRY_LOG_EXP_HST，meta_dr_qry_log_tgt_all_hst） 的INNER JOIN，这三个表数据量都在百万级别，且都是分区表（以acctstringdate为分区键），执行计划如下：
复制代码 代码如下:
------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost | Pstart| Pstop |
------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 159 | 8654 | | |
| 1 | PX COORDINATOR | | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10002 | 1 | 159 | 8654 | | |
| 3 | SORT UNIQUE | | 1 | 159 | 8654 | | |
| 4 | PX RECEIVE | | 1 | 36 | 3 | | |
| 5 | PX SEND HASH | :TQ10001 | 1 | 36 | 3 | | |
|* 6 | TABLE ACCESS BY LOCAL INDEX ROWID| DR_QRY_LOG_EXP_HST | 1 | 36 | 3 | | |
| 7 | NESTED LOOPS | | 1 | 159 | 8633 | | |
| 8 | NESTED LOOPS | | 8959 | 1076K| 4900 | | |
| 9 | BUFFER SORT | | | | | | |
| 10 | PX RECEIVE | | | | | | |
| 11 | PX SEND BROADCAST | :TQ10000 | | | | | |
| 12 | PARTITION RANGE ITERATOR | | 1 | 56 | 4746 | KEY | 14 |
|* 13 | TABLE ACCESS FULL | META_DR_QRY_LOG_TGT_ALL_HST | 1 | 56 | 4746 | KEY | 14 |
| 14 | PX BLOCK ITERATOR | | 8959 | 586K| 154 | KEY | KEY |
|* 15 | TABLE ACCESS FULL | META_DBQL_TABLE_USAGE_EXP_HST | 8959 | 586K| 154 | KEY | KEY |
| 16 | PARTITION RANGE ITERATOR | | 1 | | 2 | KEY | KEY |
|* 17 | INDEX RANGE SCAN | DR_QRY_LOG_EXP_HST_IDX | 1 | | 2 | KEY | KEY |
------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
6 - filter("RL"."STATEMENT_ID"="TGT"."STATEMENT_ID" AND "RL"."SYSTEMNAME"="TGT"."SYSTEMNAME" AND "SRC"."SYSTEMNAME"="RL"."SYSTEMNAME")
13 - filter(UPPER("TGT"."SYSTEMNAME")='MOZART' AND UPPER("TGT"."DATABASENAME")='GDW_TABLES' AND
UPPER("TGT"."TABLENAME")='SSA_SLNG_LSTG_MTRC_SD' AND "TGT"."ACCTSTRINGDATE">SYSDATE@!-30 AND "TGT"."SYSTEMNAME" IS NOT NULL
"TGT"."DATABASENAME" IS NOT NULL AND "TGT"."TABLENAME" IS NOT NULL)
15 - filter("SRC"."ACCTSTRINGDATE"="TGT"."ACCTSTRINGDATE" AND (UPPER("TGT"."SYSTEMNAME")UPPER("SRC"."SYSTEMNAME") OR
UPPER("TGT"."DATABASENAME")UPPER("SRC"."DATABASENAME") OR UPPER("TGT"."TABLENAME")UPPER("SRC"."TABLENAME")) AND
"SRC"."ACCTSTRINGDATE">SYSDATE@!-30)
17 - access("SRC"."QUERYID"="RL"."QUERYID" AND "SRC"."ACCTSTRINGDATE"="RL"."ACCTSTRINGDATE")
filter("RL"."ACCTSTRINGDATE">SYSDATE@!-30)