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Teach datum_image_eq() about cstring datums. 

Bring datum_image_eq() in line with datumIsEqual() by adding support for
comparing cstring datums.

An upcoming patch that adds deduplication to the nbtree AM will use
datum_image_eq().  datum_image_eq() will need to work with all datatypes
that can be used as the storage type of a B-Tree index column, including
cstring.  (cstring is used as the storage type for columns of type
"name" as a space-saving optimization.)

Discussion: https://postgr.es/m/CAH2-Wzn3Ee49Gmxb7V1VJ3-AC8fWn-Fr8pfWQebHe8rYRxt5OQ@mail.gmail.com
This commit is contained in:
Peter Geoghegan 2019-11-12 11:25:34 -08:00
parent 7a0574b50e
commit 8c951687f5
1 changed files with 16 additions and 3 deletions
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19
src/backend/utils/adt/datum.c
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@ -263,6 +263,8 @@ datumIsEqual(Datum value1, Datum value2, bool typByVal, int typLen)
bool
datum_image_eq(Datum value1, Datum value2, bool typByVal, int typLen)
{
Size len1,
len2;
bool result = true;
if (typByVal)
@ -277,9 +279,6 @@ datum_image_eq(Datum value1, Datum value2, bool typByVal, int typLen)
}
else if (typLen == -1)
{
Size len1,
len2;
len1 = toast_raw_datum_size(value1);
len2 = toast_raw_datum_size(value2);
/* No need to de-toast if lengths don't match. */
@ -304,6 +303,20 @@ datum_image_eq(Datum value1, Datum value2, bool typByVal, int typLen)
pfree(arg2val);
}
}
else if (typLen == -2)
{
char *s1,
*s2;
/* Compare cstring datums */
s1 = DatumGetCString(value1);
s2 = DatumGetCString(value2);
len1 = strlen(s1) + 1;
len2 = strlen(s2) + 1;
if (len1 != len2)
return false;
result = (memcmp(s1, s2, len1) == 0);
}
else
elog(ERROR, "unexpected typLen: %d", typLen);