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Postpone aggregate checks until after collation is assigned.

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Previously, parseCheckAggregates was run before
assign_query_collations, but this causes problems if any expression
has already had a collation assigned by some transform function (e.g.
transformCaseExpr) before parseCheckAggregates runs. The differing
collations would cause expressions not to be recognized as equal to
the ones in the GROUP BY clause, leading to spurious errors about
unaggregated column references.

The result was that CASE expr WHEN val ... would fail when "expr"
contained a GROUPING() expression or matched one of the group by
expressions, and where collatable types were involved; whereas the
supposedly identical CASE WHEN expr = val ... would succeed.

Backpatch all the way; this appears to have been wrong ever since
collations were introduced.

Per report from Guillaume Lelarge, analysis and patch by me.

Discussion: https://postgr.es/m/CAECtzeVSO_US8C2Khgfv54ZMUOBR4sWq+6_bLrETnWExHT=rFg@mail.gmail.com
Discussion: https://postgr.es/m/87muo0k0c7.fsf@news-spur.riddles.org.uk
This commit is contained in:
Andrew Gierth 2019-01-17 05:33:01 +00:00
parent 6afea53c30
commit e74d8c5085
5 changed files with 75 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
src/backend/parser/analyze.c
View File

@ -451,11 +451,13 @@ transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt)
qry->hasWindowFuncs = pstate->p_hasWindowFuncs;
qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
qry->hasAggs = pstate->p_hasAggs;
if (pstate->p_hasAggs)
parseCheckAggregates(pstate, qry);
assign_query_collations(pstate, qry);
/* this must be done after collations, for reliable comparison of exprs */
if (pstate->p_hasAggs)
parseCheckAggregates(pstate, qry);
return qry;
}
@ -1318,8 +1320,6 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
qry->hasWindowFuncs = pstate->p_hasWindowFuncs;
qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
qry->hasAggs = pstate->p_hasAggs;
if (pstate->p_hasAggs || qry->groupClause || qry->groupingSets || qry->havingQual)
parseCheckAggregates(pstate, qry);
foreach(l, stmt->lockingClause)
{
@ -1329,6 +1329,10 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
assign_query_collations(pstate, qry);
/* this must be done after collations, for reliable comparison of exprs */
if (pstate->p_hasAggs || qry->groupClause || qry->groupingSets || qry->havingQual)
parseCheckAggregates(pstate, qry);
return qry;
}
@ -1790,8 +1794,6 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
qry->hasWindowFuncs = pstate->p_hasWindowFuncs;
qry->hasTargetSRFs = pstate->p_hasTargetSRFs;
qry->hasAggs = pstate->p_hasAggs;
if (pstate->p_hasAggs || qry->groupClause || qry->groupingSets || qry->havingQual)
parseCheckAggregates(pstate, qry);
foreach(l, lockingClause)
{
@ -1801,6 +1803,10 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
assign_query_collations(pstate, qry);
/* this must be done after collations, for reliable comparison of exprs */
if (pstate->p_hasAggs || qry->groupClause || qry->groupingSets || qry->havingQual)
parseCheckAggregates(pstate, qry);
return qry;
}

19
src/test/regress/expected/aggregates.out
View File

@ -2116,3 +2116,22 @@ SELECT min(x ORDER BY y) FROM (VALUES(1, 2)) AS d(x,y);
1
(1 row)
-- check collation-sensitive matching between grouping expressions
select v||'a', case v||'a' when 'aa' then 1 else 0 end, count(*)
from unnest(array['a','b']) u(v)
group by v||'a' order by 1;
?column? | case | count
----------+------+-------
aa | 1 | 1
ba | 0 | 1
(2 rows)
select v||'a', case when v||'a' = 'aa' then 1 else 0 end, count(*)
from unnest(array['a','b']) u(v)
group by v||'a' order by 1;
?column? | case | count
----------+------+-------
aa | 1 | 1
ba | 0 | 1
(2 rows)

25
src/test/regress/expected/groupingsets.out
View File

@ -1540,4 +1540,29 @@ explain (costs off)
-> Seq Scan on tenk1
(12 rows)
-- check collation-sensitive matching between grouping expressions
-- (similar to a check for aggregates, but there are additional code
-- paths for GROUPING, so check again here)
select v||'a', case grouping(v||'a') when 1 then 1 else 0 end, count(*)
from unnest(array[1,1], array['a','b']) u(i,v)
group by rollup(i, v||'a') order by 1,3;
?column? | case | count
----------+------+-------
aa | 0 | 1
ba | 0 | 1
| 1 | 2
| 1 | 2
(4 rows)
select v||'a', case when grouping(v||'a') = 1 then 1 else 0 end, count(*)
from unnest(array[1,1], array['a','b']) u(i,v)
group by rollup(i, v||'a') order by 1,3;
?column? | case | count
----------+------+-------
aa | 0 | 1
ba | 0 | 1
| 1 | 2
| 1 | 2
(4 rows)
-- end

8
src/test/regress/sql/aggregates.sql
View File

@ -935,3 +935,11 @@ SELECT dense_rank(x) WITHIN GROUP (ORDER BY x) FROM (VALUES (1),(1),(2),(2),(3),
-- 2a505161-2727-2473-7c46-591ed108ac52@email.cz
SELECT min(x ORDER BY y) FROM (VALUES(1, NULL)) AS d(x,y);
SELECT min(x ORDER BY y) FROM (VALUES(1, 2)) AS d(x,y);
-- check collation-sensitive matching between grouping expressions
select v||'a', case v||'a' when 'aa' then 1 else 0 end, count(*)
from unnest(array['a','b']) u(v)
group by v||'a' order by 1;
select v||'a', case when v||'a' = 'aa' then 1 else 0 end, count(*)
from unnest(array['a','b']) u(v)
group by v||'a' order by 1;

11
src/test/regress/sql/groupingsets.sql
View File

@ -415,4 +415,15 @@ explain (costs off)
count(*)
from tenk1 group by grouping sets (unique1,twothousand,thousand,hundred,ten,four,two);
-- check collation-sensitive matching between grouping expressions
-- (similar to a check for aggregates, but there are additional code
-- paths for GROUPING, so check again here)
select v||'a', case grouping(v||'a') when 1 then 1 else 0 end, count(*)
from unnest(array[1,1], array['a','b']) u(i,v)
group by rollup(i, v||'a') order by 1,3;
select v||'a', case when grouping(v||'a') = 1 then 1 else 0 end, count(*)
from unnest(array[1,1], array['a','b']) u(i,v)
group by rollup(i, v||'a') order by 1,3;
-- end