Re: Hot Standby, release candidate?

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Hot Standby, release candidate?
Date: 2009-12-14 23:23:36
Message-ID: 1260833017.1955.2674.camel@ebony
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On Mon, 2009-12-14 at 16:39 -0500, Tom Lane wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> > What is the best way of restricting the hash table to a maximum size?
>
> There is nothing in dynahash that will enforce a maximum size against
> calling code that's not cooperating; and I'll resist any attempt to
> add such a thing, because it would create a serialization point across
> the whole hashtable.

No problem, just checking with you where you'd like stuff put.

> If you know that you need at most N entries in the hash table, you can
> preallocate that many at startup (note the second arg to ShmemInitHash)
> and be safe. If your calling code might go past that, you'll need to
> fix the calling code.

It's easy enough to count em on the way in and count em on the way out.

--
Simon Riggs www.2ndQuadrant.com

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