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Standardize on the assumption that the arguments of a RowExpr correspond

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to the physical layout of the rowtype, ie, there are dummy arguments
corresponding to any dropped columns in the rowtype.  We formerly had a
couple of places that did it this way and several others that did not.
Fixes Gaetano Mendola's "cache lookup failed for type 0" bug of 5-Aug.
This commit is contained in:
Tom Lane
2004-08-17 18:47:09 +00:00
parent 388ffad040
commit fcaad7e2c1
8 changed files with 236 additions and 60 deletions
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61
src/backend/optimizer/util/clauses.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.177 2004/08/02 01:30:43 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.178 2004/08/17 18:47:08 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@@ -40,6 +40,7 @@
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/syscache.h"
#include "utils/typcache.h"
typedef struct
@@ -1054,6 +1055,33 @@ set_coercionform_dontcare_walker(Node *node, void *context)
context);
}
/*
* Helper for eval_const_expressions: check that datatype of an attribute
* is still what it was when the expression was parsed. This is needed to
* guard against improper simplification after ALTER COLUMN TYPE. (XXX we
* may well need to make similar checks elsewhere?)
*/
static bool
rowtype_field_matches(Oid rowtypeid, int fieldnum,
Oid expectedtype, int32 expectedtypmod)
{
TupleDesc tupdesc;
Form_pg_attribute attr;
/* No issue for RECORD, since there is no way to ALTER such a type */
if (rowtypeid == RECORDOID)
return true;
tupdesc = lookup_rowtype_tupdesc(rowtypeid, -1);
if (fieldnum <= 0 || fieldnum > tupdesc->natts)
return false;
attr = tupdesc->attrs[fieldnum - 1];
if (attr->attisdropped ||
attr->atttypid != expectedtype ||
attr->atttypmod != expectedtypmod)
return false;
return true;
}
/*--------------------
* eval_const_expressions
@@ -1630,6 +1658,10 @@ eval_const_expressions_mutator(Node *node,
* parser, because ParseComplexProjection short-circuits it. But
* it can arise while simplifying functions.) Also, we can
* optimize field selection from a RowExpr construct.
*
* We must however check that the declared type of the field is
* still the same as when the FieldSelect was created --- this
* can change if someone did ALTER COLUMN TYPE on the rowtype.
*/
FieldSelect *fselect = (FieldSelect *) node;
FieldSelect *newfselect;
@@ -1640,11 +1672,15 @@ eval_const_expressions_mutator(Node *node,
if (arg && IsA(arg, Var) &&
((Var *) arg)->varattno == InvalidAttrNumber)
{
return (Node *) makeVar(((Var *) arg)->varno,
fselect->fieldnum,
fselect->resulttype,
fselect->resulttypmod,
((Var *) arg)->varlevelsup);
if (rowtype_field_matches(((Var *) arg)->vartype,
fselect->fieldnum,
fselect->resulttype,
fselect->resulttypmod))
return (Node *) makeVar(((Var *) arg)->varno,
fselect->fieldnum,
fselect->resulttype,
fselect->resulttypmod,
((Var *) arg)->varlevelsup);
}
if (arg && IsA(arg, RowExpr))
{
@@ -1652,7 +1688,18 @@ eval_const_expressions_mutator(Node *node,
if (fselect->fieldnum > 0 &&
fselect->fieldnum <= list_length(rowexpr->args))
return (Node *) list_nth(rowexpr->args, fselect->fieldnum - 1);
{
Node *fld = (Node *) list_nth(rowexpr->args,
fselect->fieldnum - 1);
if (rowtype_field_matches(rowexpr->row_typeid,
fselect->fieldnum,
fselect->resulttype,
fselect->resulttypmod) &&
fselect->resulttype == exprType(fld) &&
fselect->resulttypmod == exprTypmod(fld))
return fld;
}
}
newfselect = makeNode(FieldSelect);
newfselect->arg = (Expr *) arg;