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Fix bug with whole-row references to append subplans.

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ExecEvalWholeRowVar incorrectly supposed that it could "bless" the source
TupleTableSlot just once per query.  But if the input is coming from an
Append (or, perhaps, other cases?) more than one slot might be returned
over the query run.  This led to "record type has not been registered"
errors when a composite datum was extracted from a non-blessed slot.

This bug has been there a long time; I guess it escaped notice because when
dealing with subqueries the planner tends to expand whole-row Vars into
RowExprs, which don't have the same problem.  It is possible to trigger
the problem in all active branches, though, as illustrated by the added
regression test.
This commit is contained in:
Tom Lane 2014-07-11 19:12:51 -04:00
parent 2865d5952d
commit cd8ba91a05
3 changed files with 47 additions and 14 deletions
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33
src/backend/executor/execQual.c
View File

@ -704,7 +704,6 @@ ExecEvalWholeRowVar(WholeRowVarExprState *wrvstate, ExprContext *econtext,
{
Var *variable = (Var *) wrvstate->xprstate.expr;
TupleTableSlot *slot;
TupleDesc slot_tupdesc;
bool needslow = false;
if (isDone)
@ -794,25 +793,14 @@ ExecEvalWholeRowVar(WholeRowVarExprState *wrvstate, ExprContext *econtext,
if (wrvstate->wrv_junkFilter != NULL)
slot = ExecFilterJunk(wrvstate->wrv_junkFilter, slot);
slot_tupdesc = slot->tts_tupleDescriptor;
/*
* If it's a RECORD Var, we'll use the slot's type ID info. It's likely
* that the slot's type is also RECORD; if so, make sure it's been
* "blessed", so that the Datum can be interpreted later.
*
* If the Var identifies a named composite type, we must check that the
* actual tuple type is compatible with it.
*/
if (variable->vartype == RECORDOID)
{
if (slot_tupdesc->tdtypeid == RECORDOID &&
slot_tupdesc->tdtypmod < 0)
assign_record_type_typmod(slot_tupdesc);
}
else
if (variable->vartype != RECORDOID)
{
TupleDesc var_tupdesc;
TupleDesc slot_tupdesc;
int i;
/*
@ -829,6 +817,8 @@ ExecEvalWholeRowVar(WholeRowVarExprState *wrvstate, ExprContext *econtext,
*/
var_tupdesc = lookup_rowtype_tupdesc(variable->vartype, -1);
slot_tupdesc = slot->tts_tupleDescriptor;
if (var_tupdesc->natts != slot_tupdesc->natts)
ereport(ERROR,
(errcode(ERRCODE_DATATYPE_MISMATCH),
@ -886,6 +876,7 @@ ExecEvalWholeRowFast(WholeRowVarExprState *wrvstate, ExprContext *econtext,
{
Var *variable = (Var *) wrvstate->xprstate.expr;
TupleTableSlot *slot;
TupleDesc slot_tupdesc;
HeapTupleHeader dtuple;
if (isDone)
@ -913,6 +904,20 @@ ExecEvalWholeRowFast(WholeRowVarExprState *wrvstate, ExprContext *econtext,
if (wrvstate->wrv_junkFilter != NULL)
slot = ExecFilterJunk(wrvstate->wrv_junkFilter, slot);
/*
* If it's a RECORD Var, we'll use the slot's type ID info. It's likely
* that the slot's type is also RECORD; if so, make sure it's been
* "blessed", so that the Datum can be interpreted later. (Note: we must
* do this here, not in ExecEvalWholeRowVar, because some plan trees may
* return different slots at different times. We have to be ready to
* bless additional slots during the run.)
*/
slot_tupdesc = slot->tts_tupleDescriptor;
if (variable->vartype == RECORDOID &&
slot_tupdesc->tdtypeid == RECORDOID &&
slot_tupdesc->tdtypmod < 0)
assign_record_type_typmod(slot_tupdesc);
/*
* Copy the slot tuple and make sure any toasted fields get detoasted.
*/

18
src/test/regress/expected/subselect.out
View File

@ -765,3 +765,21 @@ select * from int4_tbl o where (f1, f1) in
(1 row)
reset enable_hashjoin;
--
-- check for over-optimization of whole-row Var referencing an Append plan
--
select (select q from
(select 1,2,3 where f1 > 0
union all
select 4,5,6.0 where f1 <= 0
) q )
from int4_tbl;
?column?
-----------
(4,5,6.0)
(1,2,3)
(4,5,6.0)
(1,2,3)
(4,5,6.0)
(5 rows)

10
src/test/regress/sql/subselect.sql
View File

@ -427,3 +427,13 @@ select * from int4_tbl o where (f1, f1) in
select * from int4_tbl o where (f1, f1) in
(select f1, generate_series(1,2) / 10 g from int4_tbl i group by f1);
reset enable_hashjoin;
--
-- check for over-optimization of whole-row Var referencing an Append plan
--
select (select q from
(select 1,2,3 where f1 > 0
union all
select 4,5,6.0 where f1 <= 0
) q )
from int4_tbl;