sql半联接优化

Question

there are two tables

t1 { id, name, ...}

t2 { t1_id , date_time, parameter, value, ...}

t1 and t2 are oracle partitioned table. t2 is large.

i want to fetch t1 which matches a time range from t2 :

select id, name, ... from t1 partition(t1_partition_name) 
where t1.id in( select distinct t1_id from t2 partition(t2_partition_name) 
             where date_time > to_date('20120627 00','YYYYMMDD HH24') 
                   and date_time <to_date('20120627 12','YYYYMMDD HH24')
          )

the sub query would return about 10K t1_id. it is really slow, any suggestion?

Answer 1

You could try:

SELECT id, name, ... 
  FROM t1 partition(t1_partition_name) aa
 WHERE EXISTS (
     SELECT * 
       FROM t2 partition(t2_partition_name) ex
      WHERE ex.t1_id = aa.id
        AND ex.date_time > to_date('20120627 00','YYYYMMDD HH24') 
        AND ex.date_time <to_date('20120627 12','YYYYMMDD HH24' )
     )
  ;

BTW I Don't know anything about Oracle's partition sub-syntax. I expect that the partition(tx_partition_name) can be removed completely, since the DBMS should already know this. It also collides with the "PARTITION BY" phrase.