Re: Re: [COMMITTERS] pgsql: Remove O(N^2) performance issue with multiple SAVEPOINTs. - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Re: [COMMITTERS] pgsql: Remove O(N^2) performance issue with multiple SAVEPOINTs.
Date
Msg-id 16113.1311267413@sss.pgh.pa.us
Whole thread Raw
In response to Re: [COMMITTERS] pgsql: Remove O(N^2) performance issue with multiple SAVEPOINTs.  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Responses Re: Re: [COMMITTERS] pgsql: Remove O(N^2) performance issue with multiple SAVEPOINTs.
List pgsql-hackers
Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
> Instead of leaving the locks dangling to an already-destroyed resource 
> owner, how about assigning all locks directly to the top-level resource 
> owner in one sweep? That'd still be much better than the old way of 
> recursively reassigning them up the subtransaction tree, one level at a 
> time.

I haven't actually read the patch, but the reason for pushing them up
only one level at a time is that if an intermediate-level subtransaction
aborts, the locks taken by its child subtransactions have to be released
at that time.  It sure sounds like this patch broke that.
        regards, tom lane


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