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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2018-01-12 15:46:37 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2018-01-12 15:46:37 -0500 |
| commit | 680d540502609b422d378a1b8e0c10cac3c60084 (patch) | |
| tree | d8790680d7cb56b0a1d47d39eeaeb493118852c6 /src/backend/optimizer/prep/prepunion.c | |
| parent | 90947674fc984f5639e3b1bf013435a023aa713b (diff) | |
| download | postgresql-680d540502609b422d378a1b8e0c10cac3c60084.tar.gz postgresql-680d540502609b422d378a1b8e0c10cac3c60084.zip | |
Avoid unnecessary failure in SELECT concurrent with ALTER NO INHERIT.
If a query against an inheritance tree runs concurrently with an ALTER
TABLE that's disinheriting one of the tree members, it's possible to get
a "could not find inherited attribute" error because after obtaining lock
on the removed member, make_inh_translation_list sees that its columns
have attinhcount=0 and decides they aren't the columns it's looking for.
An ideal fix, perhaps, would avoid including such a just-removed member
table in the query at all; but there seems no way to accomplish that
without adding expensive catalog rechecks or creating a likelihood of
deadlocks. Instead, let's just drop the check on attinhcount. In this
way, a query that's included a just-disinherited child will still
succeed, which is not a completely unreasonable behavior.
This problem has existed for a long time, so back-patch to all supported
branches. Also add an isolation test verifying related behaviors.
Patch by me; the new isolation test is based on Kyotaro Horiguchi's work.
Discussion: https://postgr.es/m/20170626.174612.23936762.horiguchi.kyotaro@lab.ntt.co.jp
Diffstat (limited to 'src/backend/optimizer/prep/prepunion.c')
| -rw-r--r-- | src/backend/optimizer/prep/prepunion.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c index e8eeabdc889..7ef391ffeb4 100644 --- a/src/backend/optimizer/prep/prepunion.c +++ b/src/backend/optimizer/prep/prepunion.c @@ -1832,7 +1832,7 @@ make_inh_translation_list(Relation oldrelation, Relation newrelation, */ if (old_attno < newnatts && (att = TupleDescAttr(new_tupdesc, old_attno)) != NULL && - !att->attisdropped && att->attinhcount != 0 && + !att->attisdropped && strcmp(attname, NameStr(att->attname)) == 0) new_attno = old_attno; else @@ -1840,7 +1840,7 @@ make_inh_translation_list(Relation oldrelation, Relation newrelation, for (new_attno = 0; new_attno < newnatts; new_attno++) { att = TupleDescAttr(new_tupdesc, new_attno); - if (!att->attisdropped && att->attinhcount != 0 && + if (!att->attisdropped && strcmp(attname, NameStr(att->attname)) == 0) break; } |