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authorMarc G. Fournier1996-09-16 05:33:20 +0000
committerMarc G. Fournier1996-09-16 05:33:20 +0000
commit475493130de825caf884d537d193d6b3ff8d0279 (patch)
tree1e23f4b09f62ee7d24723603a0e37491af8c3899
parentc5dd292007c3948a44e085c26205c1242e7ec350 (diff)
|Subject: Postgres patch: Assert attribute type match
| |Here's a patch for Version 2 only. It just adds an Assert to catch some |inconsistencies in the catalog classes. | |-- |Bryan Henderson Phone 408-227-6803 |San Jose, California |
-rw-r--r--src/backend/executor/execQual.c28
-rw-r--r--src/include/access/tupdesc.h21
2 files changed, 32 insertions, 17 deletions
diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index 104c1f2f506..fe2744d1e20 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.1.1.1 1996/07/09 06:21:25 scrappy Exp $
+ * $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.2 1996/09/16 05:33:20 scrappy Exp $
*
*-------------------------------------------------------------------------
*/
@@ -172,8 +172,24 @@ ExecEvalAggreg(Aggreg *agg, ExprContext *econtext, bool *isNull)
*
* Returns a Datum whose value is the value of a range
* variable with respect to given expression context.
- * ----------------------------------------------------------------
- */
+ *
+ *
+ * As an entry condition, we expect that the the datatype the
+ * plan expects to get (as told by our "variable" argument) is in
+ * fact the datatype of the attribute the plan says to fetch (as
+ * seen in the current context, identified by our "econtext"
+ * argument).
+ *
+ * If we fetch a Type A attribute and Caller treats it as if it
+ * were Type B, there will be undefined results (e.g. crash).
+ * One way these might mismatch now is that we're accessing a
+ * catalog class and the type information in the pg_attribute
+ * class does not match the hardcoded pg_attribute information
+ * (in pg_attribute.h) for the class in question.
+ *
+ * We have an Assert to make sure this entry condition is met.
+ *
+ * ---------------------------------------------------------------- */
Datum
ExecEvalVar(Var *variable, ExprContext *econtext, bool *isNull)
{
@@ -211,8 +227,12 @@ ExecEvalVar(Var *variable, ExprContext *econtext, bool *isNull)
heapTuple = slot->val;
tuple_type = slot->ttc_tupleDescriptor;
buffer = slot->ttc_buffer;
-
+
attnum = variable->varattno;
+
+ /* (See prolog for explanation of this Assert) */
+ Assert(attnum < 0 ||
+ variable->vartype == tuple_type->attrs[attnum-1]->atttypid)
/*
* If the attribute number is invalid, then we are supposed to
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index 75945b625d6..b6cb6f447e7 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
- * $Id: tupdesc.h,v 1.1 1996/08/27 21:50:26 scrappy Exp $
+ * $Id: tupdesc.h,v 1.2 1996/09/16 05:33:13 scrappy Exp $
*
*-------------------------------------------------------------------------
*/
@@ -18,21 +18,16 @@
#include "nodes/pg_list.h" /* for List */
#include "catalog/pg_attribute.h"
-/*
- * a TupleDesc is an array of AttributeTupleForms, each of which is a
- * pointer to a AttributeTupleForm
- */
-/* typedef AttributeTupleForm *TupleDesc; */
-
-/* a TupleDesc is a pointer to a structure which includes an array of */
-/* AttributeTupleForms, i.e. pg_attribute information, and the size of */
-/* the array, i.e. the number of attributes */
-/* in short, a TupleDesc completely captures the attribute information */
-/* for a tuple */
typedef struct tupleDesc {
- int natts;
+/*------------------------------------------------------------------------
+ This structure contains all the attribute information (i.e. from Class
+ pg_attribute) for a tuple.
+-------------------------------------------------------------------------*/
+ int natts;
+ /* Number of attributes in the tuple */
AttributeTupleForm *attrs;
+ /* attrs[N] is a pointer to the description of Attribute Number N+1. */
} *TupleDesc;
extern TupleDesc CreateTemplateTupleDesc(int natts);