From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Proposed fix for bug #14826 (the invalid empty array business) |
Date: | 2017-09-23 20:26:23 |
Message-ID: | 20570.1506198383@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
I poked around among the callers of construct_[md_]array() and found at
least two more besides ts_lexize() that could build zero-element arrays;
one of very ancient standing is in the pg_prepared_statements view.
So I think we've got a clear hazard here that justifies changing the
behavior of the low-level array functions, rather than expecting every
call site to be on its guard about empty arrays. Accordingly, I propose
the attached patch which makes construct_md_array responsible for getting
this right.
In principle we could now remove code from the places that do take care to
call construct_empty_array instead. But I found only one place where it
really seemed worth removing anything, in ExecEvalArrayExpr.
I'm a little bit scared about back-patching this, as it seems at least
possible that some external code could be broken by the change in what
construct_[md_]array could hand back. Given that some of these bugs
have been in place for ~ten years and nobody noticed till now, seems
like it might be good enough to fix them in HEAD only.
Comments?
regards, tom lane
Attachment | Content-Type | Size |
---|---|---|
handle-empty-arrays-correctly-always.patch | text/x-diff | 2.5 KB |
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