From: | "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> |
---|---|
To: | "Thomas Lee" <tom(at)vector-seven(dot)com> |
Cc: | <pgsql-patches(at)postgresql(dot)org> |
Subject: | Re: [UPDATED] A GUC variable to replace PGBE_ACTIVITY_SIZE |
Date: | 2008-06-30 10:59:28 |
Message-ID: | 4868BC90.2080209@enterprisedb.com |
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Thread: | |
Lists: | pgsql-patches |
Thomas Lee wrote:
> An updated patch for the track_activity_query_size GUC variable.
Thanks, committed with some changes.
There was one bug: BackendStatusShmemSize() needs to report the memory
needed for the activity string buffers; it's used for sizing the single
fixed size shmem block on postmaster startup. I also fixed the
documentation to refer to the setting with the right name, noted that
it's a startup time option, and changed the wording a bit.
I tested the performance between strcpy and memcpy a little bit. As
expected, strcpy is a lot cheaper if the string is small. I chose
strcpy, since it's very likely that the buffer is over-sized, and even
if it's just the right size to hold typical queries, it's going to be
"<IDLE>" for idle connections.
Another simple optimization occurred to me while looking at this: we
should skip the memcpy/strcpy altogether if the BackendActivity slot is
not in use. That seems like a good bet, you usually don't try to max out
max_connections.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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