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a477bfc1df
eval_const_expressions sometimes produced RelabelType nodes that were useless because they just relabeled an expression to the same exposed type it already had. This is worth avoiding because it can cause two equivalent expressions to not be equal(), preventing recognition of useful optimizations. In the test case added here, an unpatched planner fails to notice that the "sqli = constant" clause renders a sort step unnecessary, because one code path produces an extra RelabelType and another doesn't. Fix by ensuring that eval_const_expressions_mutator's T_RelabelType case will not add in an unnecessary RelabelType. Also save some code by sharing a subroutine with the effectively-equivalent cases for CollateExpr and CoerceToDomain. (CollateExpr had no bug, and I think that the case couldn't arise with CoerceToDomain, but it seems prudent to do the same check for all three cases.) Back-patch to v12. In principle this has been wrong all along, but I haven't seen a case where it causes visible misbehavior before v12, so refrain from changing stable branches unnecessarily. Per investigation of a report from Eric Gillum. Discussion: https://postgr.es/m/CAMmjdmvAZsUEskHYj=KT9sTukVVCiCSoe_PBKOXsncFeAUDPCQ@mail.gmail.com
271 lines
8.7 KiB
SQL
271 lines
8.7 KiB
SQL
--
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-- Tests for the planner's "equivalence class" mechanism
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--
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-- One thing that's not tested well during normal querying is the logic
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-- for handling "broken" ECs. This is because an EC can only become broken
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-- if its underlying btree operator family doesn't include a complete set
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-- of cross-type equality operators. There are not (and should not be)
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-- any such families built into Postgres; so we have to hack things up
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-- to create one. We do this by making two alias types that are really
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-- int8 (so we need no new C code) and adding only some operators for them
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-- into the standard integer_ops opfamily.
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create type int8alias1;
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create function int8alias1in(cstring) returns int8alias1
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strict immutable language internal as 'int8in';
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create function int8alias1out(int8alias1) returns cstring
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strict immutable language internal as 'int8out';
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create type int8alias1 (
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input = int8alias1in,
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output = int8alias1out,
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like = int8
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);
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create type int8alias2;
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create function int8alias2in(cstring) returns int8alias2
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strict immutable language internal as 'int8in';
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create function int8alias2out(int8alias2) returns cstring
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strict immutable language internal as 'int8out';
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create type int8alias2 (
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input = int8alias2in,
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output = int8alias2out,
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like = int8
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);
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create cast (int8 as int8alias1) without function;
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create cast (int8 as int8alias2) without function;
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create cast (int8alias1 as int8) without function;
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create cast (int8alias2 as int8) without function;
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create function int8alias1eq(int8alias1, int8alias1) returns bool
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strict immutable language internal as 'int8eq';
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create operator = (
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procedure = int8alias1eq,
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leftarg = int8alias1, rightarg = int8alias1,
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commutator = =,
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restrict = eqsel, join = eqjoinsel,
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merges
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);
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alter operator family integer_ops using btree add
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operator 3 = (int8alias1, int8alias1);
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create function int8alias2eq(int8alias2, int8alias2) returns bool
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strict immutable language internal as 'int8eq';
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create operator = (
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procedure = int8alias2eq,
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leftarg = int8alias2, rightarg = int8alias2,
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commutator = =,
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restrict = eqsel, join = eqjoinsel,
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merges
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);
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alter operator family integer_ops using btree add
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operator 3 = (int8alias2, int8alias2);
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create function int8alias1eq(int8, int8alias1) returns bool
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strict immutable language internal as 'int8eq';
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create operator = (
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procedure = int8alias1eq,
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leftarg = int8, rightarg = int8alias1,
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restrict = eqsel, join = eqjoinsel,
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merges
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);
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alter operator family integer_ops using btree add
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operator 3 = (int8, int8alias1);
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create function int8alias1eq(int8alias1, int8alias2) returns bool
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strict immutable language internal as 'int8eq';
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create operator = (
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procedure = int8alias1eq,
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leftarg = int8alias1, rightarg = int8alias2,
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restrict = eqsel, join = eqjoinsel,
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merges
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);
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alter operator family integer_ops using btree add
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operator 3 = (int8alias1, int8alias2);
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create function int8alias1lt(int8alias1, int8alias1) returns bool
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strict immutable language internal as 'int8lt';
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create operator < (
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procedure = int8alias1lt,
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leftarg = int8alias1, rightarg = int8alias1
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);
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alter operator family integer_ops using btree add
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operator 1 < (int8alias1, int8alias1);
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create function int8alias1cmp(int8, int8alias1) returns int
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strict immutable language internal as 'btint8cmp';
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alter operator family integer_ops using btree add
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function 1 int8alias1cmp (int8, int8alias1);
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create table ec0 (ff int8 primary key, f1 int8, f2 int8);
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create table ec1 (ff int8 primary key, f1 int8alias1, f2 int8alias2);
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create table ec2 (xf int8 primary key, x1 int8alias1, x2 int8alias2);
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-- for the moment we only want to look at nestloop plans
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set enable_hashjoin = off;
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set enable_mergejoin = off;
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--
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-- Note that for cases where there's a missing operator, we don't care so
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-- much whether the plan is ideal as that we don't fail or generate an
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-- outright incorrect plan.
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--
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explain (costs off)
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select * from ec0 where ff = f1 and f1 = '42'::int8;
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explain (costs off)
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select * from ec0 where ff = f1 and f1 = '42'::int8alias1;
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explain (costs off)
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select * from ec1 where ff = f1 and f1 = '42'::int8alias1;
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explain (costs off)
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select * from ec1 where ff = f1 and f1 = '42'::int8alias2;
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explain (costs off)
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select * from ec1, ec2 where ff = x1 and ff = '42'::int8;
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explain (costs off)
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select * from ec1, ec2 where ff = x1 and ff = '42'::int8alias1;
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explain (costs off)
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select * from ec1, ec2 where ff = x1 and '42'::int8 = x1;
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explain (costs off)
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select * from ec1, ec2 where ff = x1 and x1 = '42'::int8alias1;
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explain (costs off)
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select * from ec1, ec2 where ff = x1 and x1 = '42'::int8alias2;
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create unique index ec1_expr1 on ec1((ff + 1));
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create unique index ec1_expr2 on ec1((ff + 2 + 1));
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create unique index ec1_expr3 on ec1((ff + 3 + 1));
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create unique index ec1_expr4 on ec1((ff + 4));
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explain (costs off)
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select * from ec1,
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(select ff + 1 as x from
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(select ff + 2 as ff from ec1
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union all
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select ff + 3 as ff from ec1) ss0
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union all
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select ff + 4 as x from ec1) as ss1
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where ss1.x = ec1.f1 and ec1.ff = 42::int8;
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explain (costs off)
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select * from ec1,
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(select ff + 1 as x from
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(select ff + 2 as ff from ec1
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union all
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select ff + 3 as ff from ec1) ss0
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union all
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select ff + 4 as x from ec1) as ss1
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where ss1.x = ec1.f1 and ec1.ff = 42::int8 and ec1.ff = ec1.f1;
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explain (costs off)
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select * from ec1,
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(select ff + 1 as x from
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(select ff + 2 as ff from ec1
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union all
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select ff + 3 as ff from ec1) ss0
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union all
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select ff + 4 as x from ec1) as ss1,
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(select ff + 1 as x from
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(select ff + 2 as ff from ec1
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union all
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select ff + 3 as ff from ec1) ss0
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union all
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select ff + 4 as x from ec1) as ss2
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where ss1.x = ec1.f1 and ss1.x = ss2.x and ec1.ff = 42::int8;
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-- let's try that as a mergejoin
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set enable_mergejoin = on;
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set enable_nestloop = off;
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explain (costs off)
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select * from ec1,
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(select ff + 1 as x from
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(select ff + 2 as ff from ec1
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union all
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select ff + 3 as ff from ec1) ss0
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union all
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select ff + 4 as x from ec1) as ss1,
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(select ff + 1 as x from
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(select ff + 2 as ff from ec1
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union all
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select ff + 3 as ff from ec1) ss0
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union all
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select ff + 4 as x from ec1) as ss2
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where ss1.x = ec1.f1 and ss1.x = ss2.x and ec1.ff = 42::int8;
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-- check partially indexed scan
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set enable_nestloop = on;
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set enable_mergejoin = off;
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drop index ec1_expr3;
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explain (costs off)
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select * from ec1,
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(select ff + 1 as x from
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(select ff + 2 as ff from ec1
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union all
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select ff + 3 as ff from ec1) ss0
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union all
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select ff + 4 as x from ec1) as ss1
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where ss1.x = ec1.f1 and ec1.ff = 42::int8;
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-- let's try that as a mergejoin
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set enable_mergejoin = on;
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set enable_nestloop = off;
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explain (costs off)
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select * from ec1,
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(select ff + 1 as x from
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(select ff + 2 as ff from ec1
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union all
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select ff + 3 as ff from ec1) ss0
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union all
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select ff + 4 as x from ec1) as ss1
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where ss1.x = ec1.f1 and ec1.ff = 42::int8;
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-- check effects of row-level security
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set enable_nestloop = on;
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set enable_mergejoin = off;
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alter table ec1 enable row level security;
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create policy p1 on ec1 using (f1 < '5'::int8alias1);
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create user regress_user_ectest;
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grant select on ec0 to regress_user_ectest;
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grant select on ec1 to regress_user_ectest;
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-- without any RLS, we'll treat {a.ff, b.ff, 43} as an EquivalenceClass
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explain (costs off)
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select * from ec0 a, ec1 b
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where a.ff = b.ff and a.ff = 43::bigint::int8alias1;
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set session authorization regress_user_ectest;
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-- with RLS active, the non-leakproof a.ff = 43 clause is not treated
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-- as a suitable source for an EquivalenceClass; currently, this is true
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-- even though the RLS clause has nothing to do directly with the EC
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explain (costs off)
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select * from ec0 a, ec1 b
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where a.ff = b.ff and a.ff = 43::bigint::int8alias1;
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reset session authorization;
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revoke select on ec0 from regress_user_ectest;
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revoke select on ec1 from regress_user_ectest;
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drop user regress_user_ectest;
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-- check that X=X is converted to X IS NOT NULL when appropriate
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explain (costs off)
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select * from tenk1 where unique1 = unique1 and unique2 = unique2;
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-- this could be converted, but isn't at present
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explain (costs off)
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select * from tenk1 where unique1 = unique1 or unique2 = unique2;
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-- check that we recognize equivalence with dummy domains in the way
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create temp table undername (f1 name, f2 int);
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create temp view overview as
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select f1::information_schema.sql_identifier as sqli, f2 from undername;
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explain (costs off) -- this should not require a sort
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select * from overview where sqli = 'foo' order by sqli;
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