From d9cb48786ee84c27dc20e3aed92bb1f1cadf95c3 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 19 Oct 2005 22:30:30 +0000
Subject: [PATCH] Better solution to the problem of labeling whole-row Datums
that are generated from subquery outputs: use the type info stored in the Var
itself. To avoid making ExecEvalVar and slot_getattr more complex and
slower, I split out the whole-row case into a separate ExecEval routine.
---
src/backend/access/common/heaptuple.c | 35 +---------
src/backend/executor/execQual.c | 92 +++++++++++++++++++++++++--
2 files changed, 87 insertions(+), 40 deletions(-)
diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index fc0a85d2ddd..5551f744bb2 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -16,7 +16,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.101 2005/10/19 18:18:32 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.102 2005/10/19 22:30:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -27,7 +27,6 @@
#include "access/tuptoaster.h"
#include "catalog/pg_type.h"
#include "executor/tuptable.h"
-#include "utils/typcache.h"
/* ----------------------------------------------------------------
@@ -595,38 +594,6 @@ heap_getsysattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
case TableOidAttributeNumber:
result = ObjectIdGetDatum(tup->t_tableOid);
break;
-
- /*
- * If the attribute number is 0, then we are supposed to return
- * the entire tuple as a row-type Datum. (Using zero for this
- * purpose is unclean since it risks confusion with "invalid attr"
- * result codes, but it's not worth changing now.)
- *
- * We have to make a copy of the tuple so we can safely insert the
- * Datum overhead fields, which are not set in on-disk tuples.
- *
- * It's possible that the passed tupleDesc is a record type that
- * hasn't been "blessed" yet, so cover that case.
- */
- case InvalidAttrNumber:
- {
- HeapTupleHeader dtup;
-
- if (tupleDesc->tdtypeid == RECORDOID &&
- tupleDesc->tdtypmod < 0)
- assign_record_type_typmod(tupleDesc);
-
- dtup = (HeapTupleHeader) palloc(tup->t_len);
- memcpy((char *) dtup, (char *) tup->t_data, tup->t_len);
-
- HeapTupleHeaderSetDatumLength(dtup, tup->t_len);
- HeapTupleHeaderSetTypeId(dtup, tupleDesc->tdtypeid);
- HeapTupleHeaderSetTypMod(dtup, tupleDesc->tdtypmod);
-
- result = PointerGetDatum(dtup);
- }
- break;
-
default:
elog(ERROR, "invalid attnum: %d", attnum);
result = 0; /* keep compiler quiet */
diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index 5a270469061..4ee9a4ca622 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.182 2005/10/19 18:18:33 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.183 2005/10/19 22:30:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -64,6 +64,8 @@ static Datum ExecEvalAggref(AggrefExprState *aggref,
bool *isNull, ExprDoneCond *isDone);
static Datum ExecEvalVar(ExprState *exprstate, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
+static Datum ExecEvalWholeRowVar(ExprState *exprstate, ExprContext *econtext,
+ bool *isNull, ExprDoneCond *isDone);
static Datum ExecEvalConst(ExprState *exprstate, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
static Datum ExecEvalParam(ExprState *exprstate, ExprContext *econtext,
@@ -448,9 +450,9 @@ ExecEvalVar(ExprState *exprstate, ExprContext *econtext,
/*
* Get the slot and attribute number we want
*
- * The asserts check that references to system attributes only appear at the
- * level of a relation scan; at higher levels, system attributes must be
- * treated as ordinary variables (since we no longer have access to the
+ * The asserts check that references to system attributes only appear at
+ * the level of a relation scan; at higher levels, system attributes must
+ * be treated as ordinary variables (since we no longer have access to the
* original tuple).
*/
attnum = variable->varattno;
@@ -505,6 +507,77 @@ ExecEvalVar(ExprState *exprstate, ExprContext *econtext,
return slot_getattr(slot, attnum, isNull);
}
+/* ----------------------------------------------------------------
+ * ExecEvalWholeRowVar
+ *
+ * Returns a Datum for a whole-row variable.
+ *
+ * This could be folded into ExecEvalVar, but we make it a separate
+ * routine so as not to slow down ExecEvalVar with tests for this
+ * uncommon case.
+ * ----------------------------------------------------------------
+ */
+static Datum
+ExecEvalWholeRowVar(ExprState *exprstate, ExprContext *econtext,
+ bool *isNull, ExprDoneCond *isDone)
+{
+ Var *variable = (Var *) exprstate->expr;
+ TupleTableSlot *slot;
+ HeapTuple tuple;
+ TupleDesc tupleDesc;
+ HeapTupleHeader dtuple;
+
+ if (isDone)
+ *isDone = ExprSingleResult;
+ *isNull = false;
+
+ Assert(variable->varattno == InvalidAttrNumber);
+
+ /*
+ * Whole-row Vars can only appear at the level of a relation scan,
+ * never in a join.
+ */
+ Assert(variable->varno != INNER);
+ Assert(variable->varno != OUTER);
+ slot = econtext->ecxt_scantuple;
+
+ tuple = slot->tts_tuple;
+ tupleDesc = slot->tts_tupleDescriptor;
+
+ /*
+ * We have to make a copy of the tuple so we can safely insert the
+ * Datum overhead fields, which are not set in on-disk tuples.
+ */
+ dtuple = (HeapTupleHeader) palloc(tuple->t_len);
+ memcpy((char *) dtuple, (char *) tuple->t_data, tuple->t_len);
+
+ HeapTupleHeaderSetDatumLength(dtuple, tuple->t_len);
+
+ /*
+ * If the Var identifies a named composite type, label the tuple
+ * with that type; otherwise use what is in the tupleDesc.
+ *
+ * It's likely that the slot's tupleDesc is a record type; if so,
+ * make sure it's been "blessed", so that the Datum can be interpreted
+ * later.
+ */
+ if (variable->vartype != RECORDOID)
+ {
+ HeapTupleHeaderSetTypeId(dtuple, variable->vartype);
+ HeapTupleHeaderSetTypMod(dtuple, variable->vartypmod);
+ }
+ else
+ {
+ if (tupleDesc->tdtypeid == RECORDOID &&
+ tupleDesc->tdtypmod < 0)
+ assign_record_type_typmod(tupleDesc);
+ HeapTupleHeaderSetTypeId(dtuple, tupleDesc->tdtypeid);
+ HeapTupleHeaderSetTypMod(dtuple, tupleDesc->tdtypmod);
+ }
+
+ return PointerGetDatum(dtuple);
+}
+
/* ----------------------------------------------------------------
* ExecEvalConst
*
@@ -2841,8 +2914,15 @@ ExecInitExpr(Expr *node, PlanState *parent)
switch (nodeTag(node))
{
case T_Var:
- state = (ExprState *) makeNode(ExprState);
- state->evalfunc = ExecEvalVar;
+ {
+ Var *var = (Var *) node;
+
+ state = (ExprState *) makeNode(ExprState);
+ if (var->varattno != InvalidAttrNumber)
+ state->evalfunc = ExecEvalVar;
+ else
+ state->evalfunc = ExecEvalWholeRowVar;
+ }
break;
case T_Const:
state = (ExprState *) makeNode(ExprState);
--
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