bool keepplan);
static void exec_simple_check_plan(PLpgSQL_execstate *estate, PLpgSQL_expr *expr);
static void exec_save_simple_expr(PLpgSQL_expr *expr, CachedPlan *cplan);
-static void exec_check_rw_parameter(PLpgSQL_expr *expr, int target_dno);
-static bool contains_target_param(Node *node, int *target_dno);
+static void exec_check_rw_parameter(PLpgSQL_expr *expr);
static bool exec_eval_simple_expr(PLpgSQL_execstate *estate,
PLpgSQL_expr *expr,
Datum *result,
/* Check to see if it's a simple expression */
exec_simple_check_plan(estate, expr);
-
- /*
- * Mark expression as not using a read-write param. exec_assign_value has
- * to take steps to override this if appropriate; that seems cleaner than
- * adding parameters to all other callers.
- */
- expr->rwparam = -1;
}
int32 valtypmod;
/*
- * If first time through, create a plan for this expression, and then see
- * if we can pass the target variable as a read-write parameter to the
- * expression. (This is a bit messy, but it seems cleaner than modifying
- * the API of exec_eval_expr for the purpose.)
+ * If first time through, create a plan for this expression.
*/
if (expr->plan == NULL)
{
- exec_prepare_plan(estate, expr, 0, true);
+ /*
+ * Mark the expression as being an assignment source, if target is a
+ * simple variable. (This is a bit messy, but it seems cleaner than
+ * modifying the API of exec_prepare_plan for the purpose. We need to
+ * stash the target dno into the expr anyway, so that it will be
+ * available if we have to replan.)
+ */
if (target->dtype == PLPGSQL_DTYPE_VAR)
- exec_check_rw_parameter(expr, target->dno);
+ expr->target_param = target->dno;
+ else
+ expr->target_param = -1; /* should be that already */
+
+ exec_prepare_plan(estate, expr, 0, true);
}
value = exec_eval_expr(estate, expr, &isnull, &valtype, &valtypmod);
ReleaseCachedPlan(cplan, true);
/* Mark expression as non-simple, and fail */
expr->expr_simple_expr = NULL;
+ expr->expr_rw_param = NULL;
return false;
}
/* Extract desired scalar expression from cached plan */
exec_save_simple_expr(expr, cplan);
-
- /* better recheck r/w safety, as it could change due to inlining */
- if (expr->rwparam >= 0)
- exec_check_rw_parameter(expr, expr->rwparam);
}
/*
prm->pflags = PARAM_FLAG_CONST;
/*
- * If it's a read/write expanded datum, convert reference to read-only,
- * unless it's safe to pass as read-write.
+ * If it's a read/write expanded datum, convert reference to read-only.
+ * (There's little point in trying to optimize read/write parameters,
+ * given the cases in which this function is used.)
*/
- if (dno != expr->rwparam)
- {
- if (datum->dtype == PLPGSQL_DTYPE_VAR)
- prm->value = MakeExpandedObjectReadOnly(prm->value,
- prm->isnull,
- ((PLpgSQL_var *) datum)->datatype->typlen);
- else if (datum->dtype == PLPGSQL_DTYPE_REC)
- prm->value = MakeExpandedObjectReadOnly(prm->value,
- prm->isnull,
- -1);
- }
+ if (datum->dtype == PLPGSQL_DTYPE_VAR)
+ prm->value = MakeExpandedObjectReadOnly(prm->value,
+ prm->isnull,
+ ((PLpgSQL_var *) datum)->datatype->typlen);
+ else if (datum->dtype == PLPGSQL_DTYPE_REC)
+ prm->value = MakeExpandedObjectReadOnly(prm->value,
+ prm->isnull,
+ -1);
return prm;
}
*/
if (datum->dtype == PLPGSQL_DTYPE_VAR)
{
- if (dno != expr->rwparam &&
+ if (param != expr->expr_rw_param &&
((PLpgSQL_var *) datum)->datatype->typlen == -1)
scratch.d.cparam.paramfunc = plpgsql_param_eval_var_ro;
else
scratch.d.cparam.paramfunc = plpgsql_param_eval_recfield;
else if (datum->dtype == PLPGSQL_DTYPE_PROMISE)
{
- if (dno != expr->rwparam &&
+ if (param != expr->expr_rw_param &&
((PLpgSQL_var *) datum)->datatype->typlen == -1)
scratch.d.cparam.paramfunc = plpgsql_param_eval_generic_ro;
else
scratch.d.cparam.paramfunc = plpgsql_param_eval_generic;
}
else if (datum->dtype == PLPGSQL_DTYPE_REC &&
- dno != expr->rwparam)
+ param != expr->expr_rw_param)
scratch.d.cparam.paramfunc = plpgsql_param_eval_generic_ro;
else
scratch.d.cparam.paramfunc = plpgsql_param_eval_generic;
* Initialize to "not simple".
*/
expr->expr_simple_expr = NULL;
+ expr->expr_rw_param = NULL;
/*
* Check the analyzed-and-rewritten form of the query to see if we will be
expr->expr_simple_typmod = exprTypmod((Node *) tle_expr);
/* We also want to remember if it is immutable or not */
expr->expr_simple_mutable = contain_mutable_functions((Node *) tle_expr);
+
+ /*
+ * Lastly, check to see if there's a possibility of optimizing a
+ * read/write parameter.
+ */
+ exec_check_rw_parameter(expr);
}
/*
* value as a read/write pointer and let the function modify the value
* in-place.
*
- * This function checks for a safe expression, and sets expr->rwparam to the
- * dno of the target variable (x) if safe, or -1 if not safe.
+ * This function checks for a safe expression, and sets expr->expr_rw_param
+ * to the address of any Param within the expression that can be passed as
+ * read/write (there can be only one); or to NULL when there is no safe Param.
+ *
+ * Note that this mechanism intentionally applies the safety labeling to just
+ * one Param; the expression could contain other Params referencing the target
+ * variable, but those must still be treated as read-only.
+ *
+ * Also note that we only apply this optimization within simple expressions.
+ * There's no point in it for non-simple expressions, because the
+ * exec_run_select code path will flatten any expanded result anyway.
+ * Also, it's safe to assume that an expr_simple_expr tree won't get copied
+ * somewhere before it gets compiled, so that looking for pointer equality
+ * to expr_rw_param will work for matching the target Param. That'd be much
+ * shakier in the general case.
*/
static void
-exec_check_rw_parameter(PLpgSQL_expr *expr, int target_dno)
+exec_check_rw_parameter(PLpgSQL_expr *expr)
{
+ int target_dno;
Oid funcid;
List *fargs;
ListCell *lc;
/* Assume unsafe */
- expr->rwparam = -1;
+ expr->expr_rw_param = NULL;
- /*
- * If the expression isn't simple, there's no point in trying to optimize
- * (because the exec_run_select code path will flatten any expanded result
- * anyway). Even without that, this seems like a good safety restriction.
- */
- if (expr->expr_simple_expr == NULL)
+ /* Done if expression isn't an assignment source */
+ target_dno = expr->target_param;
+ if (target_dno < 0)
return;
/*
if (!bms_is_member(target_dno, expr->paramnos))
return;
+ /* Shouldn't be here for non-simple expression */
+ Assert(expr->expr_simple_expr != NULL);
+
/*
* Top level of expression must be a simple FuncExpr, OpExpr, or
- * SubscriptingRef.
+ * SubscriptingRef, else we can't optimize.
*/
if (IsA(expr->expr_simple_expr, FuncExpr))
{
F_ARRAY_SUBSCRIPT_HANDLER)
return;
- /* refexpr can be a simple Param, otherwise must not contain target */
- if (!(sbsref->refexpr && IsA(sbsref->refexpr, Param)) &&
- contains_target_param((Node *) sbsref->refexpr, &target_dno))
- return;
+ /* We can optimize the refexpr if it's the target, otherwise not */
+ if (sbsref->refexpr && IsA(sbsref->refexpr, Param))
+ {
+ Param *param = (Param *) sbsref->refexpr;
- /* the other subexpressions must not contain target */
- if (contains_target_param((Node *) sbsref->refupperindexpr,
- &target_dno) ||
- contains_target_param((Node *) sbsref->reflowerindexpr,
- &target_dno) ||
- contains_target_param((Node *) sbsref->refassgnexpr,
- &target_dno))
- return;
+ if (param->paramkind == PARAM_EXTERN &&
+ param->paramid == target_dno + 1)
+ {
+ /* Found the Param we want to pass as read/write */
+ expr->expr_rw_param = param;
+ return;
+ }
+ }
- /* OK, we can pass target as a read-write parameter */
- expr->rwparam = target_dno;
return;
}
else
return;
/*
- * The target variable (in the form of a Param) must only appear as a
- * direct argument of the top-level function.
+ * The target variable (in the form of a Param) must appear as a direct
+ * argument of the top-level function. References further down in the
+ * tree can't be optimized; but on the other hand, they don't invalidate
+ * optimizing the top-level call, since that will be executed last.
*/
foreach(lc, fargs)
{
Node *arg = (Node *) lfirst(lc);
- /* A Param is OK, whether it's the target variable or not */
if (arg && IsA(arg, Param))
- continue;
- /* Otherwise, argument expression must not reference target */
- if (contains_target_param(arg, &target_dno))
- return;
- }
-
- /* OK, we can pass target as a read-write parameter */
- expr->rwparam = target_dno;
-}
-
-/*
- * Recursively check for a Param referencing the target variable
- */
-static bool
-contains_target_param(Node *node, int *target_dno)
-{
- if (node == NULL)
- return false;
- if (IsA(node, Param))
- {
- Param *param = (Param *) node;
+ {
+ Param *param = (Param *) arg;
- if (param->paramkind == PARAM_EXTERN &&
- param->paramid == *target_dno + 1)
- return true;
- return false;
+ if (param->paramkind == PARAM_EXTERN &&
+ param->paramid == target_dno + 1)
+ {
+ /* Found the Param we want to pass as read/write */
+ expr->expr_rw_param = param;
+ return;
+ }
+ }
}
- return expression_tree_walker(node, contains_target_param,
- (void *) target_dno);
}
/* ----------
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