From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Robert John Shepherd" <robert(at)reviewer(dot)co(dot)uk> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Do Views offer any performance advantage? |
Date: | 2003-04-15 17:26:23 |
Message-ID: | 8832.1050427583@sss.pgh.pa.us |
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Lists: | pgsql-performance |
"Robert John Shepherd" <robert(at)reviewer(dot)co(dot)uk> writes:
> Whilst I often use views for convenience, is there any performance
> advantage at all in using a view rather than running the same query
> directly on the tables themselves?
No, a view is just a macro.
There is probably some minuscule cost difference involved --- you save
parsing and parse analysis of a long query string. On the other hand,
you pay to pull the view definition from the catalogs and merge it into
the given query. I'd not care to hazard a guess on whether the actual
net cost is more or less; but in any case these costs will be swamped
by query planning and execution, if the query is complex.
If you're concerned about reducing parse/plan overhead for repetitive
queries, the prepared-statement facility (new in 7.3) is what to look
at. Views won't do much for you.
regards, tom lane
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