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:

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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)