Changeset: 61e78182ddc7 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=61e78182ddc7
Modified Files:
sql/server/rel_optimizer.c
sql/server/rel_unnest.c
Branch: Jun2020
Log Message:
Performance fix for tpcds q41. At rel_join2semijoin, if the single projection
is a grouping column on an under relation, the re-write to semijoin can be
made. Also fixed cardinality for grouping expressions after unnesting
diffs (85 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
@@ -5399,22 +5399,33 @@ rel_remove_empty_join(mvc *sql, sql_rel
return rel;
}
-/* const or groupby without group by exps */
-#define SIMPLE_PROJECTION_FOR_JOIN2SEMI(X) \
- ((X)->card < CARD_AGGR && is_project((X)->op) && list_length((X)->exps)
== 1)
+static inline bool
+find_simple_projection_for_join2semi(sql_rel *rel)
+{
+ if (is_project(rel->op) && list_length(rel->exps) == 1) {
+ if (rel->card < CARD_AGGR) /* const or groupby without group by
exps */
+ return true;
+ sql_exp *found = rel_find_exp(rel->l, rel->exps->h->data); /*
grouping column on inner relation */
+ if (found && found->card <= CARD_AGGR)
+ return true;
+ }
+ return false;
+}
static sql_rel *
-find_candidate_join2semi(sql_rel *rel, bool *swap)
+find_candidate_join2semi(sql_rel *rel, bool *swap)
{
/* generalize possibility : we need the visitor 'step' here */
+ if (rel_is_ref(rel))
+ return NULL;
if (rel->op == op_join && rel->exps) {
sql_rel *l = rel->l, *r = rel->r;
- if (SIMPLE_PROJECTION_FOR_JOIN2SEMI(r)) {
+ if (find_simple_projection_for_join2semi(r)) {
*swap = false;
return rel;
}
- if (SIMPLE_PROJECTION_FOR_JOIN2SEMI(l)) {
+ if (find_simple_projection_for_join2semi(l)) {
*swap = true;
return rel;
}
@@ -5464,7 +5475,7 @@ static sql_rel *
rel_join2semijoin(mvc *sql, sql_rel *rel, int *changes)
{
(void)sql;
- if ((is_simple_project(rel->op) || is_groupby(rel->op) ||
is_select(rel->op)) && rel->l) {
+ if ((is_simple_project(rel->op) || is_groupby(rel->op) ||
(is_select(rel->op) && !rel_is_ref(rel))) && rel->l) {
bool swap = false;
sql_rel *l = rel->l;
sql_rel *c = find_candidate_join2semi(l, &swap);
diff --git a/sql/server/rel_unnest.c b/sql/server/rel_unnest.c
--- a/sql/server/rel_unnest.c
+++ b/sql/server/rel_unnest.c
@@ -1642,6 +1642,20 @@ exp_reset_card(mvc *sql, sql_rel *rel, s
if (!e || !rel || !rel->l)
return e;
+ if (is_groupby(rel->op)) {
+ switch(e->type) {
+ case e_aggr:
+ case e_column:
+ e->card = CARD_AGGR;
+ break;
+ case e_func:
+ case e_convert:
+ case e_cmp:
+ case e_atom:
+ case e_psm:
+ break;
+ }
+ }
if (!is_simple_project(rel->op)) /* only need to fix projections */
return e;
sql_rel *l;
@@ -1657,7 +1671,7 @@ exp_reset_card(mvc *sql, sql_rel *rel, s
case e_aggr: /* should have been corrected by rewrites already */
case e_cmp:
case e_atom:
- default:
+ case e_psm:
break;
}
return e;
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