From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
Cc: | pgsql-committers(at)postgresql(dot)org |
Subject: | Re: pgsql: Pull up isReset flag from AllocSetContext to MemoryContext struc |
Date: | 2011-05-22 18:18:06 |
Message-ID: | 26356.1306088286@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-committers |
Heikki Linnakangas <heikki(dot)linnakangas(at)iki(dot)fi> writes:
> Pull up isReset flag from AllocSetContext to MemoryContext struct. This
> avoids the overhead of one function call when calling MemoryContextReset(),
> and it seems like the isReset optimization would be applicable to any new
> memory context we might invent in the future anyway.
> This buys back the overhead I just added in previous patch to always call
> MemoryContextReset() in ExecScan, even when there's no quals or projections.
Do you actually have any measurements that prove that? This seems like
a rather ugly destruction of a modularity boundary in return for a
hypothetical performance gain. I'm also concerned that you've probably
added cycles on net to MemoryContextAlloc (where it's no longer possible
to tail-call AllocSetAlloc), which could very easily cost more cycles on
most workloads than could ever be saved by making MemoryContextReset a
shade faster.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2011-05-22 19:17:15 | pgsql: Make plpgsql provide the typmods for its variables to the main p |
Previous Message | Peter Eisentraut | 2011-05-22 17:07:43 | pgsql: Put documentation of backslash commands back in alphabetical ord |