From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Dann Corbit" <DCorbit(at)connx(dot)com> |
Cc: | "Steve Crawford" <scrawford(at)pinpointresearch(dot)com>, pgsql-performance(at)postgreSQL(dot)org, pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: Terrible performance on wide selects |
Date: | 2003-01-23 00:30:04 |
Message-ID: | 25725.1043281804@sss.pgh.pa.us |
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Lists: | pgsql-hackers pgsql-performance |
"Dann Corbit" <DCorbit(at)connx(dot)com> writes:
> For the disk case, why not have the start of the record contain an array
> of offsets to the start of the data for each column? It would only be
> necessary to have a list for variable fields.
No, you'd need an entry for *every* column (or at least, every one to
the right of the first variable-width column or NULL). That's a lot of
overhead, especially in comparison to datatypes like bool or int4 ...
regards, tom lane
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