Changeset: 56459e18d59d for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/56459e18d59d
Modified Files:
sql/server/rel_optimizer.c
Branch: Jul2021
Log Message:
Make a distinct projection selectable for a semijoin only if a single column is
projected
diffs (24 lines):
diff --git a/sql/server/rel_optimizer.c b/sql/server/rel_optimizer.c
--- a/sql/server/rel_optimizer.c
+++ b/sql/server/rel_optimizer.c
@@ -5321,15 +5321,16 @@ find_projection_for_join2semi(sql_rel *r
sql_exp *found = NULL;
bool underjoin = false;
- /* if just one groupby column is projected, it
will be distinct */
- if ((is_groupby(rel->op) && list_length(rel->r)
== 1 && exps_find_exp(rel->r, e)) || need_distinct(rel) || find_prop(e->p,
PROP_HASHCOL))
+ /* if just one groupby column is projected or
the relation needs distinct values and one column is projected or is a primary
key, it will be distinct */
+ if ((is_groupby(rel->op) && list_length(rel->r)
== 1 && exps_find_exp(rel->r, e)) ||
+ (is_simple_project(rel->op) &&
need_distinct(rel) && list_length(rel->exps) == 1) || find_prop(e->p,
PROP_HASHCOL))
return true;
if ((found =
rel_find_exp_and_corresponding_rel(rel->l, e, &res, &underjoin)) && !underjoin)
{ /* grouping column on inner relation */
- if (find_prop(found->p, PROP_HASHCOL))
/* primary key always unique */
+ if ((is_simple_project(res->op) &&
need_distinct(res) && list_length(res->exps) == 1) || find_prop(found->p,
PROP_HASHCOL))
return true;
if (found->type == e_column &&
found->card <= CARD_AGGR) {
- if (!(is_groupby(res->op) ||
need_distinct(res)) && list_length(res->exps) != 1)
+ if (!is_groupby(res->op) &&
list_length(res->exps) != 1)
return false;
for (node *n = res->exps->h ; n
; n = n->next) { /* must be the single column in the group by expression list */
sql_exp *e = n->data;
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