10BC0 Preserve AND/OR flatness while extracting restriction OR clauses. · postgrespro/postgres_cluster@1b4cc49 · GitHub
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Preserve AND/OR flatness while extracting restriction OR clauses.
The code I added in commit f343a88 was careless about preserving AND/OR flatness: it could create a structure with an OR node directly underneath another one. That breaks an assumption that's fairly important for planning efficiency, not to mention triggering various Asserts (as reported by Benjamin Smith). Add a trifle more logic to handle the case properly.
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‎src/backend/optimizer/util/orclauses.c‎

Lines changed: 10 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -178,6 +178,7 @@ extract_or_clause(RestrictInfo *or_rinfo, RelOptInfo *rel)
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{
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Node *orarg = (Node *) lfirst(lc);
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List *subclauses = NIL;
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Node *subclause;
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/* OR arguments should be ANDs or sub-RestrictInfos */
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if (and_clause(orarg))
@@ -226,9 +227,16 @@ extract_or_clause(RestrictInfo *or_rinfo, RelOptInfo *rel)
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/*
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* OK, add subclause(s) to the result OR. If we found more than one,
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* we need an AND node.
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* we need an AND node. But if we found only one, and it is itself an
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* OR node, add its subclauses to the result instead; this is needed
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* to preserve AND/OR flatness (ie, no OR directly underneath OR).
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*/
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clauselist = lappend(clauselist, make_ands_explicit(subclauses));
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subclause = (Node *) make_ands_explicit(subclauses);
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if (or_clause(subclause))
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clauselist = list_concat(clauselist,
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list_copy(((BoolExpr *) subclause)->args));
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else
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clauselist = lappend(clauselist, subclause);
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}
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/*

‎src/test/regress/expected/join.out‎

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Original file line numberDiff line numberDiff line change
@@ -2827,6 +2827,33 @@ select * from tenk1 a join tenk1 b on
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Index Cond: (unique2 = 3)
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(12 rows)
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explain (costs off)
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select * from tenk1 a join tenk1 b on
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(a.unique1 = 1 and b.unique1 = 2) or
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((a.unique2 = 3 or a.unique2 = 7) and b.hundred = 4);
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QUERY PLAN
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----------------------------------------------------------------------------------------------------------------------
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Nested Loop
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Join Filter: (((a.unique1 = 1) AND (b.unique1 = 2)) OR (((a.unique2 = 3) OR (a.unique2 = 7)) AND (b.hundred = 4)))
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-> Bitmap Heap Scan on tenk1 b
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Recheck Cond: ((unique1 = 2) OR (hundred = 4))
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-> BitmapOr
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-> Bitmap Index Scan on tenk1_unique1
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Index Cond: (unique1 = 2)
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-> Bitmap Index Scan on tenk1_hundred
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Index Cond: (hundred = 4)
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-> Materialize
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-> Bitmap Heap Scan on tenk1 a
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Recheck Cond: ((unique1 = 1) OR (unique2 = 3) OR (unique2 = 7))
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-> BitmapOr
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-> Bitmap Index Scan on tenk1_unique1
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Index Cond: (unique1 = 1)
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-> Bitmap Index Scan on tenk1_unique2
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Index Cond: (unique2 = 3)
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-> Bitmap Index Scan on tenk1_unique2
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Index Cond: (unique2 = 7)
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(19 rows)
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--
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-- test placement of movable quals in a parameterized join tree
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--

‎src/test/regress/sql/join.sql‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -774,6 +774,10 @@ select * from tenk1 a join tenk1 b on
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explain (costs off)
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select * from tenk1 a join tenk1 b on
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(a.unique1 = 1 and b.unique1 = 2) or (a.unique2 = 3 and b.ten = 4);
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explain (costs off)
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select * from tenk1 a join tenk1 b on
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(a.unique1 = 1 and b.unique1 = 2) or
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((a.unique2 = 3 or a.unique2 = 7) and b.hundred = 4);
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--
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-- test placement of movable quals in a parameterized join tree

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