From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Ryan Bradetich" <rbradetich(at)gmail(dot)com> |
Cc: | "Gregory Stark" <stark(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Question regarding the database page layout. |
Date: | 2008-09-02 15:07:52 |
Message-ID: | 14022.1220368072@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
"Ryan Bradetich" <rbradetich(at)gmail(dot)com> writes:
> The patch concept is fairly simple.
> 1. Add a new boolean local variable: require_max_align
> (initialized to false).
This really can't possibly work, because you'd need to propagate
knowledge of the tuple's alignment requirement all over the place.
In particular, how would code *reading* the tuple know where the
data starts? Also, I don't think you get (very much of) the actual
benefit unless the code that inserts tuples into disk pages knows
to do something different in the int-align case.
It's conceivable that we could make this work if we wanted to dedicate
an infomask bit to showing whether the tuple needs int or double
alignment. I don't really think it's worth the trouble though.
regards, tom lane
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