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Properly initialize SortSupport for ORDER BY rechecks in nodeIndexscan.c.
Fix still another bug in commit 35fcb1b3d
: it failed to fully initialize
the SortSupport states it introduced to allow the executor to re-check
ORDER BY expressions containing distance operators. That led to a null
pointer dereference if the sortsupport code tried to use ssup_cxt. The
problem only manifests in narrow cases, explaining the lack of previous
field reports. It requires a GiST-indexable distance operator that lacks
SortSupport and is on a pass-by-ref data type, which among core+contrib
seems to be only btree_gist's interval opclass; and it requires the scan
to be done as an IndexScan not an IndexOnlyScan, which explains how
btree_gist's regression test didn't catch it. Per bug #14134 from
Jihyun Yu.
Peter Geoghegan
Report: <20160511154904.2603.43889@wrigleys.postgresql.org>
This commit is contained in:
@ -967,9 +967,20 @@ ExecInitIndexScan(IndexScan *node, EState *estate, int eflags)
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Oid orderbyop = lfirst_oid(lco);
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Node *orderbyexpr = (Node *) lfirst(lcx);
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Oid orderbyType = exprType(orderbyexpr);
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Oid orderbyColl = exprCollation(orderbyexpr);
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SortSupport orderbysort = &indexstate->iss_SortSupport[i];
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/* Initialize sort support */
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orderbysort->ssup_cxt = CurrentMemoryContext;
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orderbysort->ssup_collation = orderbyColl;
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/* See cmp_orderbyvals() comments on NULLS LAST */
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orderbysort->ssup_nulls_first = false;
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/* ssup_attno is unused here and elsewhere */
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orderbysort->ssup_attno = 0;
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/* No abbreviation */
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orderbysort->abbreviate = false;
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PrepareSortSupportFromOrderingOp(orderbyop, orderbysort);
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PrepareSortSupportFromOrderingOp(orderbyop,
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&indexstate->iss_SortSupport[i]);
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get_typlenbyval(orderbyType,
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&indexstate->iss_OrderByTypLens[i],
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&indexstate->iss_OrderByTypByVals[i]);
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