Are you on 12.1.0.2 ?
On Tue, Apr 17, 2018 at 3:49 PM, Dominic Brooks <dombrooks@xxxxxxxxxxx>
wrote:
In addition to invisible indexes not being so invisible, I hash
partitioned some global PK indexes to reduce insert hot block contention.
These two things – invisible local indexes with some unusable
subpartitions and hash partitioned PK indexes - are the only things which
changed.
I’ve now got a few handfuls of statements which, in addition to some of
them doing table expansion thanks to the not-so-invisible invisible
indexes, are doing crazy long hard parsing – like 30 to 40 minutes. And
that causes knock-on effects to other sessions in the same workflow for the
same sql / objects with “cursor: pin S wait on X” and “library cache lock”
The likely culprit is dynamic sampling. I can see the sessions doing lots
of IO against different table partitions as part of the hard parse.
Otherwise the health of the database is no less healthy than it was before
and the SQL is the same SQL as it was before.
Whilst I wait for an optimizer trace file and some other dumps/traces, any
wild theories as to why just hash partitioning a global PK might cause this?
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*From:* Dominic Brooks <dombrooks@xxxxxxxxxxx>
*Sent:* Tuesday, April 10, 2018 11:09:03 AM
*To:* oracle-l@xxxxxxxxxxxxx
*Subject:* Re: Invisible indexes and table expansion
Probably just covered by bug 16544878.
Sent from my iPhone
On 10 Apr 2018, at 10:50, Dominic Brooks <dombrooks@xxxxxxxxxxx> wrote:reproduce. And it’s difficult for me to get an optimiser trace file in the
Just working through a problem, gathering evidence and trying to
environment.
table expansion - VW_TE_2.
In an 11.2.0.4 environment, I’ve got a whole bunch of queries now using
partitions as usable - something which table expansion was designed to help
Recent change was to add three local indexes, each with a subset of
with.
to cause table expansion - but then can’t be used.
But they are invisible indexes.
So my theory is the invisibility is limited - ie they are visible enough
Anyone looked into something similar?
Cheers
Dominic
Sent from my iPhone
