Thanks... interesting... no, no global statistics on the index.
Yes, can get them gathered.
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx <oracle-l-bounce@xxxxxxxxxxxxx> on behalf
of Andy Sayer <andysayer@xxxxxxxxx>
Sent: Tuesday, April 17, 2018 11:55:16 AM
To: oracle-l-freelists
Subject: Re: Crazy dynamic sampling?
I’ve experienced this before, the global statistics of the indexes in question
were missing.
It is certainly buggy looking behaviour for the dynamic sampling to do full
index scans, if you trace the execution you will see (or rather I saw in my
case) that the dynamic sampling queries were hinting for full index scans. I
didn’t get as far as looking on MOS but I suspect there will be something there.
Are you able to gather/set the statistics at a global level?
Anecdotally, it happened to me while inserting into a table over a DB link, one
of the recursive queries during the parse was a select * from table@remote,
which was pretty strange. Don’t think the issue is limited to this though.
Hope that helps.
Andrew