Changeset: d19e20576c8b for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/d19e20576c8b
Modified Files:
sql/server/rel_optimizer.c
sql/server/rel_rel.c
sql/server/rel_rel.h
sql/server/rel_unnest.c
sql/test/miscellaneous/Tests/simple_plans.test
Branch: default
Log Message:
Be less restrict pushing down selections under projections.
Push down selections before projections requiring distinct get rewritten into
groupings. Small cleanup
If I get a performance regression I will backout this.
diffs (202 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
@@ -25,7 +25,8 @@
typedef struct global_props {
int cnt[ddl_maxops];
uint8_t
- has_mergetable:1;
+ has_mergetable:1,
+ needs_distinct:1;
} global_props;
static int
@@ -337,6 +338,7 @@ rel_properties(mvc *sql, global_props *g
case op_topn:
case op_sample:
case op_truncate:
+ gp->needs_distinct |= need_distinct(rel);
if (rel->l)
rel_properties(sql, gp, rel->l);
break;
@@ -2593,7 +2595,7 @@ is_fk_column_of_pk(mvc *sql, sql_rel *re
return NULL;
}
-static inline sql_rel *
+static sql_rel *
rel_distinct_project2groupby(visitor *v, sql_rel *rel)
{
sql_rel *l = rel->l;
@@ -2894,7 +2896,7 @@ rel_merge_projects(visitor *v, sql_rel *
prj && prj->op == op_project && !(rel_is_ref(prj)) && !prj->r) {
int all = 1;
- if (project_unsafe(rel,0,0) || project_unsafe(prj,0,0) ||
exps_share_expensive_exp(rel->exps, prj->exps))
+ if (project_unsafe(rel,0) || project_unsafe(prj,0) ||
exps_share_expensive_exp(rel->exps, prj->exps))
return rel;
/* here we need to fix aliases */
@@ -3396,8 +3398,8 @@ rel_merge_union(visitor *v, sql_rel *rel
sql_rel *ref = NULL;
if (is_union(rel->op) &&
- l && is_project(l->op) && !project_unsafe(l,0,0) &&
- r && is_project(r->op) && !project_unsafe(r,0,0) &&
+ l && is_project(l->op) && !project_unsafe(l,0) &&
+ r && is_project(r->op) && !project_unsafe(r,0) &&
(ref = rel_find_ref(l)) != NULL && ref == rel_find_ref(r)) {
/* Find selects and try to merge */
sql_rel *ls = rel_find_select(l);
@@ -4686,8 +4688,8 @@ rel_push_select_down(visitor *v, sql_rel
if (is_select(rel->op) && r && r->op == op_project && !rel_is_ref(r) &&
!is_single(r)){
sql_rel *pl = r->l;
- /* we cannot push through rank (row_number etc) functions or
projects with distinct */
- if (pl && !project_unsafe(r, 1, 1)) {
+ /* we cannot push through window functions (for safety I
disabled projects over DDL too) */
+ if (pl && pl->op != op_ddl && !exps_have_unsafe(r->exps, 1)) {
/* introduce selects under the project (if needed) */
set_processed(pl);
for (n = exps->h; n;) {
@@ -5552,7 +5554,7 @@ rel_push_project_down_union(visitor *v,
sql_rel *ul = u->l;
sql_rel *ur = u->r;
- if (!u || !is_union(u->op) || need_distinct(u) || !u->exps ||
rel_is_ref(u) || project_unsafe(rel,0,0))
+ if (!u || !is_union(u->op) || need_distinct(u) || !u->exps ||
rel_is_ref(u) || project_unsafe(rel,0))
return rel;
/* don't push project down union of single values */
if ((is_project(ul->op) && !ul->l) || (is_project(ur->op) &&
!ur->l))
@@ -6360,8 +6362,8 @@ rel_push_project_up(visitor *v, sql_rel
(is_left(rel->op) && (rel->flag&MERGE_LEFT) /* can't push
projections above merge statments left joins */) ||
(is_select(rel->op) && l->op != op_project) ||
(is_join(rel->op) && ((l->op != op_project && r->op !=
op_project) || is_topn(r->op) || is_sample(r->op))) ||
- ((l->op == op_project && (!l->l || l->r ||
project_unsafe(l,is_select(rel->op),0))) ||
- (is_join(rel->op) && (r->op == op_project && (!r->l || r->r
|| project_unsafe(r,0,0))))))
+ ((l->op == op_project && (!l->l || l->r ||
project_unsafe(l,is_select(rel->op)))) ||
+ (is_join(rel->op) && (r->op == op_project && (!r->l || r->r
|| project_unsafe(r,0))))))
return rel;
if (l->op == op_project && l->l) {
@@ -6687,7 +6689,7 @@ rel_exps_mark_used(sql_allocator *sa, sq
}
/* for count/rank we need atleast one column */
if (!nr && subrel && (is_project(subrel->op) || is_base(subrel->op)) &&
!list_empty(subrel->exps) &&
- (is_simple_project(rel->op) && project_unsafe(rel, 0, 0))) {
+ (is_simple_project(rel->op) && project_unsafe(rel, 0))) {
sql_exp *e = subrel->exps->h->data;
e->used = 1;
}
@@ -9504,7 +9506,6 @@ static sql_rel *
rel_first_level_optimizations(visitor *v, sql_rel *rel)
{
rel = rel_distinct_aggregate_on_unique_values(v, rel);
- rel = rel_distinct_project2groupby(v, rel);
/* rel_simplify_math optimizer requires to clear the hash, so make sure
it runs last in this batch */
if (v->value_based_opt)
rel = rel_simplify_math(v, rel);
@@ -9798,6 +9799,9 @@ optimize_rel(mvc *sql, sql_rel *rel, int
if (gp.cnt[op_topn] || gp.cnt[op_sample])
rel = rel_visitor_topdown(&v, rel,
&rel_push_topn_and_sample_down);
+ if (level <= 0 && gp.needs_distinct && gp.cnt[op_project])
+ rel = rel_visitor_bottomup(&v, rel,
&rel_distinct_project2groupby);
+
if (gp.has_mergetable)
rel = rel_visitor_topdown(&v, rel, &rel_merge_table_rewrite);
diff --git a/sql/server/rel_rel.c b/sql/server/rel_rel.c
--- a/sql/server/rel_rel.c
+++ b/sql/server/rel_rel.c
@@ -25,25 +25,24 @@ rel_set_exps(sql_rel *rel, list *exps)
/* some projections results are order dependend (row_number etc) */
int
-project_unsafe(sql_rel *rel, int allow_identity, int allow_self_reference)
+project_unsafe(sql_rel *rel, int allow_identity)
{
sql_rel *sub = rel->l;
- node *n;
if (need_distinct(rel) || rel->r /* order by */)
return 1;
- if (!rel->exps)
+ if (list_empty(rel->exps))
return 0;
/* projects without sub and projects around ddl's cannot be changed */
- if (!sub || (sub && sub->op == op_ddl))
+ if (!sub || sub->op == op_ddl)
return 1;
- for(n = rel->exps->h; n; n = n->next) {
+ for(node *n = rel->exps->h; n; n = n->next) {
sql_exp *e = n->data, *ne;
/* aggr func in project ! */
if (exp_unsafe(e, allow_identity))
return 1;
- if (!allow_self_reference && (ne = rel_find_exp(rel, e)) && ne
!= e)
+ if ((ne = rel_find_exp(rel, e)) && ne != e)
return 1; /* no self referencing */
}
return 0;
diff --git a/sql/server/rel_rel.h b/sql/server/rel_rel.h
--- a/sql/server/rel_rel.h
+++ b/sql/server/rel_rel.h
@@ -52,7 +52,7 @@
#define is_sql_merge(X) ((X & sql_merge) == sql_merge)
extern void rel_set_exps(sql_rel *rel, list *exps);
-extern int project_unsafe(sql_rel *rel, int allow_identity, int
allow_self_reference);
+extern int project_unsafe(sql_rel *rel, int allow_identity);
extern const char *rel_name( sql_rel *r );
extern sql_rel *rel_distinct(sql_rel *l);
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
@@ -3296,7 +3296,7 @@ rewrite_remove_xp_project(visitor *v, sq
if (rel->op == op_join && list_empty(rel->exps)) {
sql_rel *r = rel->r;
- if (is_simple_project(r->op) && r->l && !project_unsafe(r, 1,
0)) {
+ if (is_simple_project(r->op) && r->l && !project_unsafe(r, 1)) {
sql_rel *rl = r->l;
if (is_simple_project(rl->op) && !rl->l &&
list_length(rl->exps) == 1) {
diff --git a/sql/test/miscellaneous/Tests/simple_plans.test
b/sql/test/miscellaneous/Tests/simple_plans.test
--- a/sql/test/miscellaneous/Tests/simple_plans.test
+++ b/sql/test/miscellaneous/Tests/simple_plans.test
@@ -561,6 +561,32 @@ project (
| ) [ "x"."x", "x"."y" ]
) [ "x"."x", "x"."y" ]
+query T nosort
+plan select x, y from (select a as b, a / 3 as c from t1 union distinct select
a as z, a / 5 as d from t2) x(x,y) where x > 2
+----
+project (
+| distinct union (
+| | project (
+| | | group by (
+| | | | project (
+| | | | | select (
+| | | | | | table("sys"."t1") [ "t1"."a" ] COUNT
+| | | | | ) [ "t1"."a" > int "2" ]
+| | | | ) [ "t1"."a" as "b", "sys"."sql_div"("t1"."a", tinyint "3") as "c" ]
+| | | ) [ "b", "c" ] [ "b", "c" ]
+| | ) [ "b" as "x"."x", "c" as "x"."y" ],
+| | project (
+| | | group by (
+| | | | project (
+| | | | | select (
+| | | | | | table("sys"."t2") [ "t2"."a" ] COUNT
+| | | | | ) [ "t2"."a" > int "2" ]
+| | | | ) [ "t2"."a" as "z", "sys"."sql_div"("t2"."a", tinyint "5") as "d" ]
+| | | ) [ "z", "d" ] [ "z", "d" ]
+| | ) [ "z" as "x"."x", "d" as "x"."y" ]
+| ) [ "x"."x", "x"."y" ]
+) [ "x"."x", "x"."y" ]
+
statement ok
rollback
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