From: Andrew Dunstan <andrew@dunslane.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Filip Rembiałkowski <filip.rembialkowski@gmail.com>
Cc: Pgsql Hackers <pgsql-hackers@postgresql.org>
Subject: Re: proposal: make NOTIFY list de-duplication optional
Date: Sat, 6 Feb 2016 12:50:59 -0500
Message-ID: <56B63283.4050508@dunslane.net> (raw)
In-Reply-To: <7647.1454723392@sss.pgh.pa.us>
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On 02/05/2016 08:49 PM, Tom Lane wrote:
> Yeah, I agree that a GUC for this is quite unappetizing.
Agreed.
>
> One idea would be to build a hashtable to aid with duplicate detection
> (perhaps only once the pending-notify list gets long).
>
> Another thought is that it's already the case that duplicate detection is
> something of a "best effort" activity; note for example the comment in
> AsyncExistsPendingNotify pointing out that we don't collapse duplicates
> across subtransactions. Would it be acceptable to relax the standards
> a bit further? For example, if we only checked for duplicates among the
> last N notification list entries (for N say around 100), we'd probably
> cover just about all the useful cases, and the runtime would stay linear.
> The data structure isn't tremendously conducive to that, but it could be
> done.
>
>
I like the hashtable idea if it can be made workable.
cheers
andrew
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Cc: andrew@dunslane.net, tgl@sss.pgh.pa.us, robertmhaas@gmail.com, filip.rembialkowski@gmail.com
Subject: Re: proposal: make NOTIFY list de-duplication optional
In-Reply-To: <56B63283.4050508@dunslane.net>
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