Changeset: 2a09928588da for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=2a09928588da
Modified Files:
sql/server/rel_rewriter.c
sql/test/miscellaneous/Tests/deallocate.stable.out
Branch: default
Log Message:
Small optimization needed for properties branch, if a select or inner join is
not going to output tuples, replace the inner relations with a dummy projection
diffs (57 lines):
diff --git a/sql/server/rel_rewriter.c b/sql/server/rel_rewriter.c
--- a/sql/server/rel_rewriter.c
+++ b/sql/server/rel_rewriter.c
@@ -176,8 +176,31 @@ rewrite_simplify(visitor *v, sql_rel *re
if (!rel)
return rel;
- if ((is_select(rel->op) || is_join(rel->op) || is_semi(rel->op)) &&
!list_empty(rel->exps))
+ if ((is_select(rel->op) || is_join(rel->op) || is_semi(rel->op)) &&
!list_empty(rel->exps)) {
rel->exps = exps_simplify_exp(v, rel->exps);
+ /* At a select or inner join relation if the single expression
is false, eliminate the inner relations with a dummy projection */
+ if (list_length(rel->exps) == 1 &&
exp_is_false(rel->exps->h->data)) {
+ if ((is_select(rel->op) || (is_innerjoin(rel->op) &&
!rel_is_ref(rel->r))) && rel->card > CARD_ATOM && !rel_is_ref(rel->l)) {
+ list *nexps = sa_list(v->sql->sa), *toconvert =
rel_projections(v->sql, rel->l, NULL, 1, 1);
+ if (is_innerjoin(rel->op))
+ toconvert = list_merge(toconvert,
rel_projections(v->sql, rel->r, NULL, 1, 1), NULL);
+
+ for (node *n = toconvert->h ; n ; n = n->next) {
+ sql_exp *e = n->data, *a =
exp_atom(v->sql->sa, atom_general(v->sql->sa, exp_subtype(e), NULL));
+ exp_prop_alias(v->sql->sa, a, e);
+ list_append(nexps, a);
+ }
+ rel_destroy(rel->l);
+ if (is_innerjoin(rel->op)) {
+ rel_destroy(rel->r);
+ rel->r = NULL;
+ rel->op = op_select;
+ }
+ rel->l = rel_project(v->sql->sa, NULL, nexps);
+ rel->card = CARD_ATOM;
+ }
+ }
+ }
return rel;
}
diff --git a/sql/test/miscellaneous/Tests/deallocate.stable.out
b/sql/test/miscellaneous/Tests/deallocate.stable.out
--- a/sql/test/miscellaneous/Tests/deallocate.stable.out
+++ b/sql/test/miscellaneous/Tests/deallocate.stable.out
@@ -87,7 +87,7 @@ stdout of test 'deallocate` in directory
[ "prepare select \"system\" or ? from sys._tables where false;", 0,
0, "boolean", 1, 0, NULL, "%1", "%1" ]
[ "prepare select \"system\" or ? from sys._tables where false;", 1,
1, "boolean", 1, 0, NULL, NULL, NULL ]
#EXEC 3(false);
-% sys.%1 # table_name
+% .%1 # table_name
% %1 # name
% boolean # type
% 5 # length
@@ -124,7 +124,7 @@ stdout of test 'deallocate` in directory
[ "boolean", 1, 0, "", "%1", "%1" ]
[ "boolean", 1, 0, NULL, NULL, NULL ]
#execute 15(false);
-% sys.%1 # table_name
+% .%1 # table_name
% %1 # name
% boolean # type
% 5 # length
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