Re: BUG #19000: gist index returns inconsistent result with gist_inet_ops

On 28.07.25 04:23, Richard Guo wrote:
> On Mon, Jul 28, 2025 at 5:16 AM PG Bug reporting form
> <noreply@postgresql.org> wrote:
>> CREATE EXTENSION btree_gist;
>>
>> CREATE TABLE t AS SELECT '192.168.1.0/25'::inet AS i;
>>
>> SELECT * FROM t WHERE i << '192.168.1.0/24'::cidr;
>>         i
>> ----------------
>>   192.168.1.0/25
>>
>> CREATE INDEX ON t USING gist(i);
>>
>> SELECT * FROM t WHERE i << '192.168.1.0/24'::cidr;
>>   i
>> ---
>> (0 rows)
> 
> It seems that with gist_inet_ops the index's opfamily does not support
> the '<<' operator correctly.
> 
> With inet_ops, the query works correctly.

The generated index condition is the same for the gist and the btree 
index, namely:

((i > '192.168.1.0/24'::inet) AND (i <= '192.168.1.255'::inet))

If I run the query with the lower bound directly, like

SELECT * FROM t WHERE i > '192.168.1.0/24'::inet;

then I also get no result rows for the gist index, but I do get one for 
the btree index.  (The upper bound works correctly in either case.)

This can be reproduced even in PG17.

My mind is a bit boggled about what the actual meaning of the > operator 
should be in this case, but in any case it seems there might be a 
pre-existing discrepancy in the btree_gist module.