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help / color / mirror / Atom feedFrom: John Naylor <[email protected]>
To: Robert Haas <[email protected]>
Cc: Lukas Fittl <[email protected]>
Cc: Jacob Champion <[email protected]>
Cc: Dian Fay <[email protected]>
Cc: Matheus Alcantara <[email protected]>
Cc: Jakub Wartak <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Subject: Re: pg_plan_advice
Date: Tue, 13 Jan 2026 18:38:51 +0700
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On Tue, Jan 13, 2026 at 12:14 AM Robert Haas <[email protected]> wrote:
> Here's v9. Changes:
This is perhaps the least interesting part of 0005, but since I
committed this API, I thought I'd chime in:
+ /* alias_name may not be NULL */
+ sp_len = fasthash_accum_cstring(&hs, key.alias_name);
+
+ /* partition_name and plan_name, however, can be NULL */
+ if (key.partition_name != NULL)
+ sp_len += fasthash_accum_cstring(&hs, key.partition_name);
+ if (key.plan_name != NULL)
+ sp_len += fasthash_accum_cstring(&hs, key.plan_name);
It looks like it would be helpful if fasthash_accum_cstring just
returned zero when given a NULL string, as in the attached. We could
also do something like add a large number to the hash, but I'm not
sure that's necessary.
+ /*
+ * hashfn_unstable.h recommends using string length as tweak. It's not
+ * clear to me what to do if there are multiple strings, so for now I'm
+ * just using the total of all of the lengths.
+ */
+ return fasthash_final32(&hs, sp_len);
Sounds reasonable, so the patch also documents that.
--
John Naylor
Amazon Web Services
Attachments:
[application/octet-stream] fasthash-zero-len.patch.nocfbot (1.1K, 2-fasthash-zero-len.patch.nocfbot)
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To: [email protected]
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Subject: Re: pg_plan_advice
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