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Implemented condition pushdown into derived tables / views

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with window functions (mdev-10855).

This patch just modified the function pushdown_cond_for_derived()
to support this feature.
Some test cases demonstrating this optimization were added to
derived_cond_pushdown.test.
This commit is contained in:
Igor Babaev
2017-08-12 19:58:16 -07:00
parent c9981fbee2
commit 61bbabb202
6 changed files with 584 additions and 14 deletions
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42
sql/sql_derived.cc
View File

@ -1243,15 +1243,51 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived)
st_select_lex *save_curr_select= thd->lex->current_select;
for (; sl; sl= sl->next_select())
{
Item *extracted_cond_copy;
if (!sl->cond_pushdown_is_allowed())
continue;
thd->lex->current_select= sl;
if (sl->have_window_funcs())
{
if (sl->join->group_list || sl->join->implicit_grouping)
continue;
if (!(sl->window_specs.elements == 1 &&
sl->window_specs.head()->partition_list))
continue;
extracted_cond_copy= !sl->next_select() ?
extracted_cond :
extracted_cond->build_clone(thd, thd->mem_root);
if (!extracted_cond_copy)
continue;
Item *cond_over_partition_fields;
ORDER *grouping_list= sl->window_specs.head()->partition_list->first;
sl->collect_grouping_fields(thd, grouping_list);
sl->check_cond_extraction_for_grouping_fields(extracted_cond_copy,
derived);
cond_over_partition_fields=
sl->build_cond_for_grouping_fields(thd, extracted_cond_copy, true);
if (cond_over_partition_fields)
cond_over_partition_fields= cond_over_partition_fields->transform(thd,
&Item::derived_grouping_field_transformer_for_where,
(uchar*) sl);
if (cond_over_partition_fields)
{
cond_over_partition_fields->walk(
&Item::cleanup_excluding_const_fields_processor, 0, 0);
sl->cond_pushed_into_where= cond_over_partition_fields;
}
continue;
}
/*
For each select of the unit except the last one
create a clone of extracted_cond
*/
Item *extracted_cond_copy= !sl->next_select() ? extracted_cond :
extracted_cond->build_clone(thd, thd->mem_root);
extracted_cond_copy= !sl->next_select() ?
extracted_cond :
extracted_cond->build_clone(thd, thd->mem_root);
if (!extracted_cond_copy)
continue;
@ -1276,7 +1312,7 @@ bool pushdown_cond_for_derived(THD *thd, Item *cond, TABLE_LIST *derived)
that could be pushed into the where clause of sl
*/
Item *cond_over_grouping_fields;
sl->collect_grouping_fields(thd);
sl->collect_grouping_fields(thd, sl->join->group_list);
sl->check_cond_extraction_for_grouping_fields(extracted_cond_copy,
derived);
cond_over_grouping_fields=