If there are not a large number of distinct values of obj_id, try a SKIP_SCAN hint. Otherwise, the secondary index should work, make sure it's actually used via explain. Finally, you might try the ROW_TIMESTAMP feature if it fits your use case.
> On Feb 22, 2017, at 11:30 PM, NaHeon Kim <[email protected]> wrote: > > Hi all, > I've seen performance problem when selecting rows within date range. > > My table schema is: > > CREATE TABLE MY_TABLE ( > OBJ_ID varchar(20) not null, > CREATE_DT timestamp not null, > KEYWORD varchar(100) not null, > COUNT integer, > CONSTRAINT PK PRIMARY KEY (OBJ_ID,CREATE_DT,KEYWORD) > ); > > MY_TABLE has almost 5,200,000 rows, > CREATE_DT has about 6 months range. > > And executed query: > > SELECT KEYWORD, SUM(COUNT) > FROM MY_TABLE > WHERE CREATE_DT > to_timestamp('2016-03-01 00:00') > AND CREATE_DT < to_timestamp('2016-04-01 00:00') > GROUP BY KEYWORD; > > It tooks 46 seconds, too slow than expected, cause CREATE_DT is one of row > key. > I created a secondary index on CREATE_DT but there's no improvement. > > Query plan looks weird: > CLIENT 2-CHUNK 0 ROWS 0 BYTES PARALLEL 2-WAY FULL SCAN OVER NEWS_KEYWORD_COUNT > SERVER FILTER BY (CREATE_DT > TIMESTAMP '2017-03-01 00:00:00.000' AND > CREATE_DT < TIMESTAMP '2017-04-01 00:00:00.000') > SERVER AGGREGATE INTO DISTINCT ROWS BY [KEYWORD] > CLIENT MERGE SORT > CLIENT 100 ROW LIMIT > > BUT If CREATE_DT comes first of row key, plan says range scan will be done. > > Any suggestion? : ) > > Thanks, > NaHeon >
