| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Jan Wieck <JanWieck(at)Yahoo(dot)com>, btober(at)seaworthysys(dot)com, scrawford(at)pinpointresearch(dot)com, kleptog(at)svana(dot)org, m_tessier(at)sympatico(dot)ca, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: How many fields in a table are too many |
| Date: | 2003-06-28 18:43:07 |
| Message-ID: | 24818.1056825787@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> However, I am not sure how useful NOT NULL is in practice because there
> are lots of columns that don't specify NOT NULL but have mostly nulls or
> mostly non-nulls, which kills our caching --- what I was hoping to do
> some day was to cache the null bitmask and offsets of the previous tuple
> and use those if the new tuple has the same null bitmask as the previous
> tuple.
We already cache fairly effectively in cases where there are no nulls.
I'm not sure it's worth trying to do something with the idea that two
adjacent tuples might have nulls in the same places.
regards, tom lane
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