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Code review for IS DISTINCT FROM patch. Fix incorrect constant-folding 

logic, dissuade planner from thinking that 'x IS DISTINCT FROM 42' may
be optimized into 'x = 42' (!!), cause dependency on = operator to be
recorded correctly, minor other improvements.
This commit is contained in:
Tom Lane 2002-11-30 21:25:08 +00:00
parent 36c356e799
commit 2b7ec402c4
7 changed files with 70 additions and 115 deletions
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5
src/backend/catalog/dependency.c
View File

@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/dependency.c,v 1.12 2002/09/22 00:37:09 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/catalog/dependency.c,v 1.13 2002/11/30 21:25:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -803,7 +803,8 @@ find_expr_references_walker(Node *node,
{
Expr *expr = (Expr *) node;
if (expr->opType == OP_EXPR)
if (expr->opType == OP_EXPR ||
expr->opType == DISTINCT_EXPR)
{
Oper *oper = (Oper *) expr->oper;

27
src/backend/executor/execQual.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.110 2002/11/25 21:29:35 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.111 2002/11/30 21:25:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1144,7 +1144,7 @@ ExecEvalFunc(Expr *funcClause,
* they are NULL; if either is NULL then the result is already
* known. If neither is NULL, then proceed to evaluate the
* function. Note that this is *always* derived from the equals
* operator, but since we've already evaluated the arguments
* operator, but since we need special processing of the arguments
* we can not simply reuse ExecEvalOper() or ExecEvalFunc().
* ----------------------------------------------------------------
*/
@ -1154,7 +1154,7 @@ ExecEvalDistinct(Expr *opClause,
bool *isNull,
ExprDoneCond *isDone)
{
bool result;
Datum result;
FunctionCachePtr fcache;
FunctionCallInfoData fcinfo;
ExprDoneCond argDone;
@ -1162,10 +1162,7 @@ ExecEvalDistinct(Expr *opClause,
List *argList;
/*
* we extract the oid of the function associated with the op and then
* pass the work onto ExecMakeFunctionResult which evaluates the
* arguments and returns the result of calling the function on the
* evaluated arguments.
* extract info from opClause
*/
op = (Oper *) opClause->oper;
argList = opClause->args;
@ -1181,34 +1178,36 @@ ExecEvalDistinct(Expr *opClause,
econtext->ecxt_per_query_memory);
op->op_fcache = fcache;
}
Assert(fcache->func.fn_retset == FALSE);
Assert(!fcache->func.fn_retset);
/* Need to prep callinfo structure */
MemSet(&fcinfo, 0, sizeof(fcinfo));
fcinfo.flinfo = &(fcache->func);
argDone = ExecEvalFuncArgs(&fcinfo, argList, econtext);
if (argDone != ExprSingleResult)
elog(ERROR, "IS DISTINCT FROM does not support set arguments");
Assert(fcinfo.nargs == 2);
if (fcinfo.argnull[0] && fcinfo.argnull[1])
{
/* Both NULL? Then is not distinct... */
result = FALSE;
result = BoolGetDatum(FALSE);
}
else if (fcinfo.argnull[0] || fcinfo.argnull[1])
{
/* One is NULL? Then is distinct... */
result = TRUE;
/* Only one is NULL? Then is distinct... */
result = BoolGetDatum(TRUE);
}
else
{
fcinfo.isnull = false;
result = FunctionCallInvoke(&fcinfo);
*isNull = fcinfo.isnull;
result = (!DatumGetBool(result));
/* Must invert result of "=" */
result = BoolGetDatum(!DatumGetBool(result));
}
return BoolGetDatum(result);
return result;
}
/* ----------------------------------------------------------------

12
src/backend/optimizer/plan/setrefs.c
View File

@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/setrefs.c,v 1.82 2002/11/19 23:21:59 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/setrefs.c,v 1.83 2002/11/30 21:25:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -575,7 +575,13 @@ fix_opids_walker(Node *node, void *context)
{
if (node == NULL)
return false;
if (is_opclause(node))
replace_opid((Oper *) ((Expr *) node)->oper);
if (IsA(node, Expr))
{
Expr *expr = (Expr *) node;
if (expr->opType == OP_EXPR ||
expr->opType == DISTINCT_EXPR)
replace_opid((Oper *) expr->oper);
}
return expression_tree_walker(node, fix_opids_walker, context);
}

124
src/backend/optimizer/util/clauses.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.113 2002/11/26 03:01:58 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/clauses.c,v 1.114 2002/11/30 21:25:04 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -98,25 +98,19 @@ make_clause(int type, Node *oper, List *args)
*
* Returns t iff the clause is an operator clause:
* (op expr expr) or (op expr).
*
* [historical note: is_clause has the exact functionality and is used
* throughout the code. They're renamed to is_opclause for clarity.
* - ay 10/94.]
*/
bool
is_opclause(Node *clause)
{
return (clause != NULL &&
IsA(clause, Expr) &&
((((Expr *) clause)->opType == OP_EXPR) ||
((Expr *) clause)->opType == DISTINCT_EXPR));
((Expr *) clause)->opType == OP_EXPR);
}
/*
* make_opclause
* Creates a clause given its operator left operand and right
* operand (if it is non-null).
*
* Creates a clause given its operator, left operand, and right
* operand (pass NULL to create single-operand clause).
*/
Expr *
make_opclause(Oper *op, Var *leftop, Var *rightop)
@ -1191,10 +1185,10 @@ eval_const_expressions_mutator(Node *node, void *context)
bool has_nonconst_input = false;
/*
* Check for constant inputs and especially
* constant-NULL inputs.
* We must do our own check for NULLs because
* DISTINCT_EXPR has different results for NULL input
* than the underlying operator does.
*/
Assert(length(args) == 2);
foreach(arg, args)
{
if (IsA(lfirst(arg), Const))
@ -1205,82 +1199,28 @@ eval_const_expressions_mutator(Node *node, void *context)
else
has_nonconst_input = true;
}
/* all nulls? then not distinct */
if (all_null_input)
return MAKEBOOLCONST(false, false);
/* one null? then distinct */
if (has_null_input)
return MAKEBOOLCONST(true, false);
/* all constants? then optimize this out */
/* all constants? then can optimize this out */
if (!has_nonconst_input)
{
Oid result_typeid;
int16 resultTypLen;
bool resultTypByVal;
ExprContext *econtext;
Datum const_val;
bool const_is_null;
/* all nulls? then not distinct */
if (all_null_input)
return MAKEBOOLCONST(false, false);
Oper *oper = (Oper *) expr->oper;
/* one null? then distinct */
if (has_null_input)
return MAKEBOOLCONST(true, false);
replace_opid(oper); /* OK to scribble on input
* to this extent */
result_typeid = oper->opresulttype;
/*
* OK, looks like we can simplify this
* operator/function.
*
* We use the executor's routine ExecEvalExpr() to
* avoid duplication of code and ensure we get the
* same result as the executor would get.
*
* Build a new Expr node containing the
* already-simplified arguments. The only other
* setup needed here is the replace_opid() that we
* already did for the OP_EXPR case.
*/
newexpr = makeNode(Expr);
newexpr->typeOid = expr->typeOid;
newexpr->opType = expr->opType;
newexpr->oper = expr->oper;
newexpr->args = args;
/* Get info needed about result datatype */
get_typlenbyval(result_typeid, &resultTypLen, &resultTypByVal);
/*
* It is OK to pass a dummy econtext because none
* of the ExecEvalExpr() code used in this
* situation will use econtext. That might seem
* fortuitous, but it's not so unreasonable --- a
* constant expression does not depend on context,
* by definition, n'est ce pas?
*/
econtext = MakeExprContext(NULL, CurrentMemoryContext);
const_val = ExecEvalExprSwitchContext((Node *) newexpr, econtext,
&const_is_null, NULL);
/*
* Must copy result out of sub-context used by
* expression eval
*/
if (!const_is_null)
const_val = datumCopy(const_val, resultTypByVal, resultTypLen);
FreeExprContext(econtext);
pfree(newexpr);
/*
* Make the constant result node.
*/
return (Node *) makeConst(result_typeid, resultTypLen,
const_val, const_is_null,
resultTypByVal);
/* otherwise try to evaluate the '=' operator */
newexpr = simplify_op_or_func(expr, args);
if (newexpr) /* successfully simplified it */
return (Node *) newexpr;
}
/*
* else fall out to build new Expr node with simplified
* args
*/
break;
}
case OR_EXPR:
@ -1624,7 +1564,14 @@ simplify_op_or_func(Expr *expr, List *args)
* Note we take the result type from the Oper or Func node, not the
* pg_proc tuple; probably necessary for binary-compatibility cases.
*/
if (expr->opType == OP_EXPR)
if (expr->opType == FUNC_EXPR)
{
Func *func = (Func *) expr->oper;
funcid = func->funcid;
result_typeid = func->funcresulttype;
}
else /* OP_EXPR or DISTINCT_EXPR */
{
Oper *oper = (Oper *) expr->oper;
@ -1632,13 +1579,6 @@ simplify_op_or_func(Expr *expr, List *args)
funcid = oper->opid;
result_typeid = oper->opresulttype;
}
else
{
Func *func = (Func *) expr->oper;
funcid = func->funcid;
result_typeid = func->funcresulttype;
}
/*
* we could use func_volatile() here, but we need several fields out
@ -1693,7 +1633,7 @@ simplify_op_or_func(Expr *expr, List *args)
*
* Build a new Expr node containing the already-simplified arguments. The
* only other setup needed here is the replace_opid() that we already
* did for the OP_EXPR case.
* did for the OP_EXPR/DISTINCT_EXPR case.
*/
newexpr = makeNode(Expr);
newexpr->typeOid = expr->typeOid;

4
src/backend/parser/parse_expr.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.131 2002/11/26 03:01:58 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.132 2002/11/30 21:25:05 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -277,6 +277,8 @@ transformExpr(ParseState *pstate, Node *expr, ConstraintTestValue *domVal)
result = (Node *) make_op(a->name,
lexpr,
rexpr);
if (((Expr *) result)->typeOid != BOOLOID)
elog(ERROR, "IS DISTINCT FROM requires = operator to yield boolean");
((Expr *) result)->opType = DISTINCT_EXPR;
}
break;

10
src/include/nodes/primnodes.h
View File

@ -10,7 +10,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: primnodes.h,v 1.70 2002/11/26 03:01:59 tgl Exp $
* $Id: primnodes.h,v 1.71 2002/11/30 21:25:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -165,6 +165,12 @@ typedef enum CoercionForm
/*
* Expr
*
* Note: DISTINCT_EXPR implements the "x IS DISTINCT FROM y" construct.
* This is similar to an OP_EXPR, except for its handling of NULL inputs.
* The oper field is always an Oper node for the "=" operator for x and y.
* (We use "=", not the more obvious "<>", because more datatypes have "="
* than "<>". This means the executor must invert the operator result.)
*/
typedef enum OpType
{
@ -183,7 +189,7 @@ typedef struct Expr
} Expr;
/*
* Oper - Expr subnode for an OP_EXPR
* Oper - Expr subnode for an OP_EXPR (or DISTINCT_EXPR)
*
* NOTE: in the good old days 'opno' used to be both (or either, or
* neither) the pg_operator oid, and/or the pg_proc oid depending

3
src/pl/plpgsql/src/pl_exec.c
View File

@ -3,7 +3,7 @@
* procedural language
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.70 2002/11/23 03:59:09 momjian Exp $
* $Header: /cvsroot/pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.71 2002/11/30 21:25:08 tgl Exp $
*
* This software is copyrighted by Jan Wieck - Hamburg.
*
@ -3509,6 +3509,7 @@ exec_simple_check_node(Node *node)
switch (expr->opType)
{
case OP_EXPR:
case DISTINCT_EXPR:
case FUNC_EXPR:
case OR_EXPR:
case AND_EXPR: