diff options
Diffstat (limited to 'src/backend/utils/adt/varlena.c')
| -rw-r--r-- | src/backend/utils/adt/varlena.c | 27 |
1 files changed, 10 insertions, 17 deletions
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c index 11b442a5941..2c398cd9e5c 100644 --- a/src/backend/utils/adt/varlena.c +++ b/src/backend/utils/adt/varlena.c @@ -1671,14 +1671,13 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid) * * Even apart from the risk of broken locales, it's possible that * there are platforms where the use of abbreviated keys should be - * disabled at compile time. Having only 4 byte datums could make - * worst-case performance drastically more likely, for example. - * Moreover, macOS's strxfrm() implementation is known to not - * effectively concentrate a significant amount of entropy from the - * original string in earlier transformed blobs. It's possible that - * other supported platforms are similarly encumbered. So, if we ever - * get past disabling this categorically, we may still want or need to - * disable it for particular platforms. + * disabled at compile time. For example, macOS's strxfrm() + * implementation is known to not effectively concentrate a + * significant amount of entropy from the original string in earlier + * transformed blobs. It's possible that other supported platforms + * are similarly encumbered. So, if we ever get past disabling this + * categorically, we may still want or need to disable it for + * particular platforms. */ if (!pg_strxfrm_enabled(locale)) abbreviate = false; @@ -2132,18 +2131,12 @@ varstr_abbrev_convert(Datum original, SortSupport ssup) addHyperLogLog(&sss->full_card, hash); /* Hash abbreviated key */ -#if SIZEOF_DATUM == 8 { - uint32 lohalf, - hihalf; + uint32 tmp; - lohalf = (uint32) res; - hihalf = (uint32) (res >> 32); - hash = DatumGetUInt32(hash_uint32(lohalf ^ hihalf)); + tmp = DatumGetUInt32(res) ^ (uint32) (DatumGetUInt64(res) >> 32); + hash = DatumGetUInt32(hash_uint32(tmp)); } -#else /* SIZEOF_DATUM != 8 */ - hash = DatumGetUInt32(hash_uint32((uint32) res)); -#endif addHyperLogLog(&sss->abbr_card, hash); |