Oracle FAQ | Your Portal to the Oracle Knowledge Grid |
Home -> Community -> Usenet -> c.d.o.server -> Forcing PQ
The software:
Oracle 8.1.7
HP-UX platform
The tables:
Big one (30+ million rows).
Several smaller ones ranging from few 100 rows to a 10's of 1000's of rows
(indexed).
All tables analyzed (estimate 10% on big one).
The query:
Straight forward full tablescan of the big one, using nested loop joins with
the smaller ones.
The result to be stored in a new table (i.e. create table unrecoverable as select). Hints ORDERED and USE_NL are used to force the correct join order. All rows in big table needs to be processed first, thus the FTS, then using nested loops with unique index scans to the smaller tables.
The problem:
The query itself is fast. Okay, relatively fast given the large number of
rows. I can also force it to run in parallel when it is a pure SELECT
count(*) (i.e. no CREATE TABLE). However, when adding the CREATE TABLE, it
ignores the PARALLEL hint in the SELECT and the PARALLEL clause in the
CREATE TABLE.
Have tried ALTER SESSION ENABLE PARALLEL DML. No change. The SQL still runs
serial.
Suggestions?
Thanks.
-- BillyReceived on Thu Aug 08 2002 - 03:40:33 CDT