Fix BRIN minmax-multi distance for inet type
The distance calculation ignored the mask, unlike the inet comparator,
which resulted in negative distance in some cases. Fixed by applying the
mask in brin_minmax_multi_distance_inet. I've considered simply calling
inetmi() to calculate the delta, but that does not consider mask either.
Discussion:
@@ -2297,6 +2297,9 @@ brin_minmax_multi_distance_inet(PG_FUNCTION_ARGS)
inet *ipa = PG_GETARG_INET_PP(0);
inet *ipb = PG_GETARG_INET_PP(1);
+ int lena,
+ lenb;
+
/*
* If the addresses are from different families, consider them to be in
* maximal possible distance (which is 1.0).
@@ -2304,24 +2307,64 @@ brin_minmax_multi_distance_inet(PG_FUNCTION_ARGS)
if (ip_family(ipa) != ip_family(ipb))
PG_RETURN_FLOAT8(1.0);
- /* ipv4 or ipv6 */
- if (ip_family(ipa) == PGSQL_AF_INET)
- len = 4;
- else
- len = 16; /* NS_IN6ADDRSZ */
+ addra = (unsigned char *) palloc(ip_addrsize(ipa));
+ memcpy(addra, ip_addr(ipa), ip_addrsize(ipa));
+
+ addrb = (unsigned char *) palloc(ip_addrsize(ipb));
+ memcpy(addrb, ip_addr(ipb), ip_addrsize(ipb));
+
+ /*
+ * The length is calculated from the mask length, because we sort the
+ * addresses by first address in the range, so A.B.C.D/24 < A.B.C.1
+ * (the first range starts at A.B.C.0, which is before A.B.C.1). We
+ * don't want to produce negative delta in this case, so we just cut
+ * the extra bytes.
+ *
+ * XXX Maybe this should be a bit more careful and cut the bits, not
+ * just whole bytes.
+ */
+ lena = ip_bits(ipa);
+ lenb = ip_bits(ipb);
+
+ len = ip_addrsize(ipa);
+
+ /* apply the network mask to both addresses */
+ for (i = 0; i < len; i++)
+ {
+ unsigned char mask;
+ int nbits;
- addra = ip_addr(ipa);
- addrb = ip_addr(ipb);
+ nbits = lena - (i * 8);
+ if (nbits < 8)
+ {
+ mask = (0xFF << (8 - nbits));
+ addra[i] = (addra[i] & mask);
+ }
+ nbits = lenb - (i * 8);
+ if (nbits < 8)
+ {
+ mask = (0xFF << (8 - nbits));
+ addrb[i] = (addrb[i] & mask);
+ }
+ }
+
+ /* Calculate the difference between the addresses. */
delta = 0;
for (i = len - 1; i >= 0; i--)
{
- delta += (float8) addrb[i] - (float8) addra[i];
+ unsigned char a = addra[i];
+ unsigned char b = addrb[i];
+
+ delta += (float8) b - (float8) a;
delta /= 256;
}
Assert((delta >= 0) && (delta <= 1));
+ pfree(addra);
+ pfree(addrb);
+
PG_RETURN_FLOAT8(delta);
}
