Analyze Table Compute Statistics but slowed down performance ??

Please help investigate my problem :-

Oracle 7.3.4 running on SCO UNIX with 1GB memory and a lot of free disk space.

Aims at improving performance, I have done the following:-
(1) drop the database and recreate and import back the data (aims at
defragmentation)
(2) increased the db_block_buffer
(3) collect statistics from utlbstat & utlestat and found that

	db_block_buffer hit ratio = 95%
	librarycache hit ratio = 99.7%
	percent memory sorts = 99.88%

After one week, I have
(5) performed the command "Analyze table ... compute statistics;" for
all the tables in the database. The optimizer_mode is CHOOSE.

However, the same posting job as point (4) ran for almost 6 hours to complete! It caused the system slowed down dramatically.

I have checked the hit ratio of db buffer and library cache and percent memory sorts are almost the same as point (3) above.

Please tell me why it happens and how to trace the problem. Thanks a lot!

Phoebe Received on Thu Jun 01 2000 - 00:00:00 CDT