| From: | Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com> |
|---|---|
| To: | Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, bashtanov(at)imap(dot)cc |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: [patch] bit XOR aggregate functions |
| Date: | 2021-03-03 14:30:15 |
| Message-ID: | ca112cc2-37e0-6f0b-5f0e-5d5fcadafd9d@enterprisedb.com |
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| Lists: | pgsql-hackers |
On 10.02.21 06:42, Kyotaro Horiguchi wrote:
> We already had CREATE AGGREATE at the time, so BIT_XOR can be thought
> as it falls into the same category with BIT_AND and BIT_OR, that is,
> we may have BIT_XOR as an intrinsic aggregation?
I think the use of BIT_XOR is quite separate from BIT_AND and BIT_OR.
The latter give you an "all" or "any" result of the bits set. BIT_XOR
will return 1 or true if an odd number of inputs are 1 or true, which
isn't useful by itself. But it can be used as a checksum, so it seems
pretty reasonable to me to add it. Perhaps the use case could be
pointed out in the documentation.
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