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，该sql如下： select /*+ parallel(s
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，该sql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
;