Changeset: 5d684f0e58ef for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=5d684f0e58ef
Modified Files:
sql/backends/monet5/rel_bin.c
Branch: in-value-list
Log Message:
Add naive cornercase handling for not-in-predicates with nulls.
diffs (55 lines):
diff --git a/sql/backends/monet5/rel_bin.c b/sql/backends/monet5/rel_bin.c
--- a/sql/backends/monet5/rel_bin.c
+++ b/sql/backends/monet5/rel_bin.c
@@ -290,6 +290,17 @@ distinct_value_list(backend *be, stmt *l
return stmt_project(be, ext, list);
}
+static sql_exp* in_value_list_contains_null(mvc* sql, list *vals) {
+ for(node* n = vals->h; n; n = n->next) {
+ sql_exp *e = n->data;
+
+ if (exp_is_null(sql, e))
+ return e;
+ }
+
+ return NULL;
+}
+
static stmt * stmt_selectnonil( backend *be, stmt *col, stmt *s );
static stmt *
@@ -332,10 +343,29 @@ handle_in_exps(backend *be, sql_exp *ce,
s = stmt_result(be, s, 0);
if (!in) {
- stmt* oid_c;
- oid_c = stmt_mirror(be, c);
- // TODO: Somehow stmt_tdiff only allows BAT[oid]
arguments hence the mirror op.
- s = stmt_tdiff(be, oid_c, s);
+ sql_exp* null_value;
+ if ((null_value = in_value_list_contains_null(be->mvc,
nl))) {
+ // CORNER CASE ALERT:
+ // In case of a not-in-expression with the
associated in-value-list containing a null value,
+ // the entire in-predicate is forced to always
return false, i.e. an empty candidate list.
+ // This is similar to postgres behavior.
+ // TODO: However I do not think this behavior
is in accordance with SQL standard 2003.
+
+ // Ugly trick to return empty candidate list,
because for all x it holds that: (x == null) == false.
+ //list* singleton_bat = sa_list(sql->sa);
+ // list_append(singleton_bat, null_value);
+ stmt* null_value_stmt;
+ null_value_stmt = exp_bin(be, null_value, left,
right, grp, ext, cnt, NULL);
+ s = stmt_uselect(be, c, null_value_stmt,
cmp_equal, NULL, 0);
+ return s;
+ }
+ else {
+ // BACK TO HAPPY FLOW:
+ stmt* oid_c;
+ // TODO: Somehow stmt_tdiff only allows
BAT[oid] arguments hence the mirror op.
+ oid_c = stmt_mirror(be, c);
+ s = stmt_tdiff(be, oid_c, s);
+ }
}
if (sel) {
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