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Make the world safe (more or less) for dropped columns in plpgsql rowtypes.

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This commit is contained in:
Tom Lane
2003-09-25 23:02:12 +00:00
parent a039148cad
commit 2848dc5fea
7 changed files with 259 additions and 196 deletions
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58
src/backend/executor/execQual.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.145 2003/09/25 06:57:59 petere Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.146 2003/09/25 23:02:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -315,23 +315,6 @@ ExecEvalAggref(AggrefExprState *aggref, 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 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.
*
* ---------------------------------------------------------------- */
static Datum
ExecEvalVar(Var *variable, ExprContext *econtext, bool *isNull)
@ -369,11 +352,40 @@ ExecEvalVar(Var *variable, ExprContext *econtext, bool *isNull)
attnum = variable->varattno;
/* (See prolog for explanation of this Assert) */
Assert(attnum <= 0 ||
(attnum - 1 <= tuple_type->natts - 1 &&
tuple_type->attrs[attnum - 1] != NULL &&
variable->vartype == tuple_type->attrs[attnum - 1]->atttypid));
/*
* Some checks that are only applied for user attribute numbers
* (bogus system attnums will be caught inside heap_getattr).
*/
if (attnum > 0)
{
/*
* This assert checks that the attnum is valid.
*/
Assert(attnum <= tuple_type->natts &&
tuple_type->attrs[attnum - 1] != NULL);
/*
* If the attribute's column has been dropped, we force a NULL result.
* This case should not happen in normal use, but it could happen if
* we are executing a plan cached before the column was dropped.
*/
if (tuple_type->attrs[attnum - 1]->attisdropped)
{
*isNull = true;
return (Datum) 0;
}
/*
* This assert checks that the datatype the plan expects to get (as
* told by our "variable" argument) is in fact the datatype of the
* attribute being fetched (as seen in the current context, identified
* by our "econtext" argument). Otherwise crashes are likely.
*
* Note that we can't check dropped columns, since their atttypid
* has been zeroed.
*/
Assert(variable->vartype == tuple_type->attrs[attnum - 1]->atttypid);
}
/*
* If the attribute number is invalid, then we are supposed to return