Hi, Ross,
This has been running for about 4 hours now. I got an SQL trace file, and
looked at the execution plans. So here's the deal. There's an interesting
join condition "...where A.col1=B.col1.....". However, A has a few hundred
distinct values in that column, none of them being NULL, and B, which has a
few hundred thousand rows, has ALL NULLs in the corresponding column, and
that column is not indexed, too. That's the query where it sits for a couple
of hours. Guess what the optimizer is doing (8i)? I think internal effects
are secondary in this scenario. It is the production (including the
database) designed by the company named DELTEK, so nobody can change the
code. Anyway, I reported my findings...
Thank you very much for your help, it's always appreciated.
Best,
Sergey

 -----Original Message-----
Sent:   Friday, January 25, 2002 12:56 PM
To:     Multiple recipients of list ORACLE-L
Subject:        RE: Session_wait

This is a busy little beaver...how long you say this runs?

opened cursors cumulative                                              1072
session logical reads                                              77233609
db block gets                                                       2642119
consistent gets                                                    74591490
physical reads                                                       148822
db block changes                                                    3005410
consistent changes                                                      141
no work - consistent read gets                                     72058049
table scans (short tables)                                           210918
table scans (long tables)                                                36
table scan rows gotten                                            798264962
table scan blocks gotten                                           71788386
table fetch by rowid                                                1074164
leaf node splits                                                       4018
execute count                                                         74445
bytes sent via SQL*Net to client                                      59650
bytes received via SQL*Net from client                                84233
SQL*Net roundtrips to/from client                                       342
buffer is not pinned count                                         73513922

I see some updates (or inserts) and heavy reads...at first glance, 
though, you don't appear to be I/O throttled but likely have inefficiencies
in buffer cache. Pin some small tables? Reexamine access paths for
fts, even if on "small" tables (generally defined to be around
5% in blocks of buffer cache size?)and consider seeking out
and destroying  nested loops joins in favor of hash joins. There's
more CPU, but less buffer cache splashing around....don't forget to
review init.ora settings for hash, buffer pools, and query planning. 
(...be happy to do a flyover of those as well, if you like.) 

That's about all i can get in a one minute glance, but there are alot of
people on the list who'll see more. Look to them for longer posts with
more explanation. 

Good Luck!

- Ross
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Author: Mohan, Ross
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