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Grab the low-hanging fruit from forcing sizeof(Datum) to 8.

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Remove conditionally-compiled code for smaller Datum widths,
and simplify comments that describe cases no longer of interest.

I also fixed up a few more places that were not using
DatumGetIntXX where they should, and made some cosmetic
adjustments such as using sizeof(int64) not sizeof(Datum)
in places where that fit better with the surrounding code.

One thing I remembered while preparing this part is that SP-GiST
stores pass-by-value prefix keys as Datums, so that the on-disk
representation depends on sizeof(Datum).  That's even more
unfortunate than the existing commentary makes it out to be,
because now there is a hazard that the change of sizeof(Datum)
will break SP-GiST indexes on 32-bit machines.  It appears that
there are no existing SP-GiST opclasses that are actually
affected; and if there are some that I didn't find, the number
of installations that are using them on 32-bit machines is
doubtless tiny.  So I'm proceeding on the assumption that we
can get away with this, but it's something to worry about.

(gininsert.c looks like it has a similar problem, but it's okay
because the "tuples" it's constructing are just transient data
within the tuplesort step.  That's pretty poorly documented
though, so I added some comments.)

Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Discussion: https://postgr.es/m/1749799.1752797397@sss.pgh.pa.us
This commit is contained in:
Tom Lane
2025-08-13 17:11:54 -04:00
parent 2a600a93c7
commit 6aebedc384
17 changed files with 72 additions and 284 deletions
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4
src/include/utils/sortsupport.h
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@@ -262,7 +262,6 @@ ApplyUnsignedSortComparator(Datum datum1, bool isNull1,
return compare;
}
#if SIZEOF_DATUM >= 8
static inline int
ApplySignedSortComparator(Datum datum1, bool isNull1,
Datum datum2, bool isNull2,
@@ -296,7 +295,6 @@ ApplySignedSortComparator(Datum datum1, bool isNull1,
return compare;
}
#endif
static inline int
ApplyInt32SortComparator(Datum datum1, bool isNull1,
@@ -376,9 +374,7 @@ ApplySortAbbrevFullComparator(Datum datum1, bool isNull1,
* are eligible for faster sorting.
*/
extern int ssup_datum_unsigned_cmp(Datum x, Datum y, SortSupport ssup);
#if SIZEOF_DATUM >= 8
extern int ssup_datum_signed_cmp(Datum x, Datum y, SortSupport ssup);
#endif
extern int ssup_datum_int32_cmp(Datum x, Datum y, SortSupport ssup);
/* Other functions in utils/sort/sortsupport.c */