Changeset: ae77acc88af6 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/ae77acc88af6
Modified Files:
sql/server/rel_optimize_proj.c
Branch: optimizer-testing
Log Message:
WIP group-by CSE with alias instead of project injection and push down
diffs (75 lines):
diff --git a/sql/server/rel_optimize_proj.c b/sql/server/rel_optimize_proj.c
--- a/sql/server/rel_optimize_proj.c
+++ b/sql/server/rel_optimize_proj.c
@@ -1703,46 +1703,39 @@ rel_groupby_cse(visitor *v, sql_rel *rel
{
if (is_groupby(rel->op) && !list_empty(rel->r)) {
sql_rel *l = rel->l;
- int needed = 0;
-
- for (node *n=((list*)rel->r)->h; n ; n = n->next) {
- sql_exp *e = n->data;
- e->used = 0; /* we need to use this flag, clean it
first */
- }
+
+ /* for every group expression e1 */
for (node *n=((list*)rel->r)->h; n ; n = n->next) {
sql_exp *e1 = n->data;
+ /* it's good to examine the same expression in the
subrelation e.g. in case it's an alias */
/* TODO maybe cover more cases? Here I only look at the
left relation */
- sql_exp *e3 = e1->type == e_column ?
exps_find_exp(l->exps, e1) : NULL;
-
+ sql_exp *e1_sub = e1->type == e_column ?
exps_find_exp(l->exps, e1) : NULL;
+
+ /* for every other group expression */
for (node *m=n->next; m; m = m->next) {
sql_exp *e2 = m->data;
- sql_exp *e4 = e2->type == e_column ?
exps_find_exp(l->exps, e2) : NULL;
-
- if (exp_match_exp(e1, e2) || exp_refers(e1, e2)
|| (e3 && e4 && (exp_match_exp(e3, e4) || exp_refers(e3, e4)))) {
- e2->used = 1; /* flag it as being
removed */
- needed = 1;
+ sql_exp *e2_sub = e2->type == e_column ?
exps_find_exp(l->exps, e2) : NULL;
+
+ /* check if the experssion are the same */
+ if (exp_match_exp(e1, e2) || exp_refers(e1, e2)
|| (e1_sub && e2_sub && (exp_match_exp(e1_sub, e2_sub) || exp_refers(e1_sub,
e2_sub)))) {
+
+ /* TODO: return checks!! */
+ sql_exp *e2_in_exps = rel_find_exp(rel,
e2);
+ node *e2_exps_node =
list_find(rel->exps, e2_in_exps, NULL);
+
+ sql_exp* e2_as_e1_alias =
exp_copy(v->sql, e1);
+ /* XXX: should we use e1 or e1_in_exps
for the alias source ???? */
+ exp_setalias(e2_as_e1_alias, e2->l,
e2->r);
+ list_append_before(rel->exps,
e2_exps_node, e2_as_e1_alias);
+
+ list_remove_node(rel->exps, NULL,
e2_exps_node);
+
+ node *e2_r_node = list_find(rel->r, e2,
NULL);
+ list_remove_node(rel->r, NULL,
e2_r_node);
+ v->changes++;
}
}
}
-
- if (!needed)
- return rel;
-
- if (!is_simple_project(l->op) || !list_empty(l->r) ||
rel_is_ref(l) || need_distinct(l))
- rel->l = l = rel_project(v->sql->sa, l,
rel_projections(v->sql, l, NULL, 1, 1));
-
- for (node *n=((list*)rel->r)->h; n ; ) {
- node *next = n->next;
- sql_exp *e = n->data;
-
- if (e->used) { /* remove unecessary grouping columns */
- e->used = 0;
- list_append(l->exps, e);
- list_remove_node(rel->r, NULL, n);
- v->changes++;
- }
- n = next;
- }
}
return rel;
}
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