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MWL#90: Subqueries: Inside-out execution for non-semijoin materialized subqueries that are AND-parts of the WHERE

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- Address feedback
- Code cleanup (not finished)
This commit is contained in:
Sergey Petrunya
2010-06-08 18:22:31 +04:00
parent 559dafdf60
commit 26c3dc455b
5 changed files with 53 additions and 113 deletions
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16
sql/item_cmpfunc.cc
View File

@@ -5733,26 +5733,10 @@ Item_field* Item_equal::get_first(Item_field *field)
It's a field from an materialized semi-join. We can substitute it only
for a field from the same semi-join.
*/
#if 0
psergey3:remove:
JOIN_TAB *first;
JOIN *join= field_tab->join;
int tab_idx= field_tab - field_tab->join->join_tab;
/* Find the first table of this semi-join nest */
for (int i= tab_idx; i >= (int)join->const_tables; i--)
{
if (join->join_tab[i].table->map & emb_nest->sj_inner_tables)
first= join->join_tab + i;
else
// Found first tab that doesn't belong to current SJ.
break;
}
#endif
/* Find an item to substitute for. */
while ((item= it++))
{
//if (item->field->table->reginfo.join_tab >= first)
if (item->field->table->pos_in_table_list->embedding == emb_nest)
{
/*

10
sql/opt_subselect.cc
View File

@@ -45,8 +45,8 @@
exception that we don't care how many matches a row from outer_tbl has in
inner_tbl.
In SQL, that translates into following: a semi-join subquery is an IN
subquery that is an AND-part of the WHERE/ON clause.
In SQL terms: a semi-join subquery is an IN subquery that is an AND-part of
the WHERE/ON clause.
2. General idea about semi-join execution
-----------------------------------------
@@ -3957,8 +3957,8 @@ static void remove_subq_pushed_predicates(JOIN *join, Item **where)
bool join_tab_execution_startup(JOIN_TAB *tab)
{
DBUG_ENTER("join_tab_execution_startup");
Item_in_subselect *in_subs;
DBUG_ENTER("join_tab_execution_startup");
if (tab->table->pos_in_table_list &&
(in_subs= tab->table->pos_in_table_list->jtbm_subselect))
{
@@ -3995,13 +3995,9 @@ bool join_tab_execution_startup(JOIN_TAB *tab)
if ((rc= sub_select(join, join_tab, FALSE/* no EOF */)) < 0 ||
(rc= sub_select(join, join_tab, TRUE/* now EOF */)) < 0)
{
//psergey3-todo: set sjm->materialized=TRUE here, too??
join->return_tab= save_return_tab;
DBUG_RETURN(rc); /* it's NESTED_LOOP_(ERROR|KILLED)*/
}
/*
Ok, materialization finished. Initialize the access to the temptable
*/
join->return_tab= save_return_tab;
sjm->materialized= TRUE;
}

46
sql/sql_join_cache.cc
View File

@@ -158,42 +158,6 @@ JOIN_TAB *next_linear_tab(JOIN* join, JOIN_TAB* tab, bool include_bush_roots);
void JOIN_CACHE::calc_record_fields()
{
//psergey4-todo: prev_cache, or
// - first non-const table if on top level
// - first table inside SJM nest if within sjm nest
// this->join_tab is 'our' join_tab
// No. the right idea: start from ... and walk to the current join_tab
/// with an iterator, skipping
// join nests (can do so for now)
/*
The above sucks, too.
The right idea:
- for SJM-inner tables, walk only within the nest
- for SJM-outer tables, use all preceding tables, including inner ones.
eof
*/
/* JOIN_TAB *tab = prev_cache ? prev_cache->join_tab :
join->join_tab+join->const_tables;
*/
/* JOIN_TAB *tab;
if (prev_cache)
tab= prev_cache->join_tab;
else
{
if (tab->bush_root_tab)
{
;
}
else
{
/ * top-level * /
tab= join->join_tab+join->const_tables;
}
}*/
JOIN_TAB *tab;
if (prev_cache)
tab= prev_cache->join_tab;
@@ -201,12 +165,18 @@ void JOIN_CACHE::calc_record_fields()
{
if (join_tab->bush_root_tab)
{
// inside SJM-Mat nest: pick first one
/*
If the tab we're attached to is inside an SJM-nest, start from the
first tab in that SJM nest
*/
tab= join_tab->bush_root_tab->bush_children->start;
}
else
{
// outside SJM-Mat nest: start from first non-const table
/*
The tab we're attached to is not inside an SJM-nest. Start from the
first non-const table.
*/
tab= join->join_tab + join->const_tables;
}
}

61
sql/sql_select.cc
View File

@@ -1011,10 +1011,10 @@ JOIN::optimize()
{
List_iterator<JOIN_TAB_RANGE> it(join_tab_ranges);
JOIN_TAB_RANGE *jt_range;
bool first= TRUE;
uint first_tab_offs= const_tables;
while ((jt_range= it++))
{
for (JOIN_TAB *tab= jt_range->start + (first ? const_tables : 0);
for (JOIN_TAB *tab= jt_range->start + first_tab_offs;
tab < jt_range->end; tab++)
{
if (*tab->on_expr_ref)
@@ -1025,7 +1025,7 @@ JOIN::optimize()
(*tab->on_expr_ref)->update_used_tables();
}
}
first= FALSE;
first_tab_offs= 0;
}
}
@@ -1298,9 +1298,11 @@ JOIN::optimize()
*/
if (need_tmp || select_distinct || group_list || order)
{
for (uint i = const_tables; i < tables; i++)
for (uint i= 0; i < tables; i++)
{
if (!(table[i]->map & const_table_map))
table[i]->prepare_for_position();
}
}
DBUG_EXECUTE("info",TEST_join(this););
@@ -5871,7 +5873,6 @@ JOIN_TAB *first_linear_tab(JOIN *join, bool after_const_tables)
first+= join->const_tables;
if (first < join->join_tab + join->top_jtrange_tables)
return first;
else
return NULL;
}
@@ -5888,24 +5889,24 @@ JOIN_TAB *first_linear_tab(JOIN *join, bool after_const_tables)
to.)
*/
JOIN_TAB *next_linear_tab(JOIN* join, JOIN_TAB* tab, bool include_bush_roots) //psergey2: added
JOIN_TAB *next_linear_tab(JOIN* join, JOIN_TAB* tab, bool include_bush_roots)
{
if (include_bush_roots && tab->bush_children)
return tab->bush_children->start;
DBUG_ASSERT(!tab->last_leaf_in_bush || tab->bush_root_tab);
if (tab->last_leaf_in_bush)
tab= tab->bush_root_tab;
if (tab->bush_root_tab)
return ++tab;
if (++tab == join->join_tab + join->top_jtrange_tables /*join->join_tab_ranges.head()->end*/)
if (++tab == join->join_tab + join->top_jtrange_tables)
return NULL;
if (!include_bush_roots && tab->bush_children)
{
tab= tab->bush_children->start;
}
return tab;
}
@@ -5929,12 +5930,12 @@ JOIN_TAB *next_linear_tab(JOIN* join, JOIN_TAB* tab, bool include_bush_roots) //
*/
JOIN_TAB *next_depth_first_tab(JOIN* join, JOIN_TAB* tab) //psergey2: added
JOIN_TAB *next_depth_first_tab(JOIN* join, JOIN_TAB* tab)
{
bool start= FALSE;
if (tab == NULL)
{
/* This means we're starting. */
/* This means we're starting the enumeration */
if (join->const_tables == join->top_jtrange_tables)
return NULL;
@@ -5945,7 +5946,11 @@ JOIN_TAB *next_depth_first_tab(JOIN* join, JOIN_TAB* tab) //psergey2: added
if (tab->last_leaf_in_bush)
return tab->bush_root_tab;
if ((start? tab: ++tab) == join->join_tab_ranges.head()->end)
/* Move to next tab in the array we're traversing*/
if (!start)
tab++;
if (tab == join->join_tab_ranges.head()->end)
return NULL; /* End */
if (tab->bush_children)
@@ -5955,7 +5960,7 @@ JOIN_TAB *next_depth_first_tab(JOIN* join, JOIN_TAB* tab) //psergey2: added
}
static Item *null_ptr= NULL;
static Item * const null_ptr= NULL;
/*
Set up join struct according to the picked join order in
@@ -6004,10 +6009,6 @@ get_best_combination(JOIN *join)
fix_semijoin_strategies_for_picked_join_order(join);
/*
psergey2-todo: Here: switch to nested structure when copying.
*/
JOIN_TAB_RANGE *root_range= new JOIN_TAB_RANGE;
root_range->start= join->join_tab;
/* root_range->end will be set later */
@@ -6041,7 +6042,7 @@ get_best_combination(JOIN *join)
j->ref.key_parts=0;
j->loosescan_match_tab= NULL; //non-nulls will be set later
j->use_join_cache= FALSE;
j->on_expr_ref= &null_ptr;
j->on_expr_ref= (Item**) &null_ptr;
j->cache= NULL;
/*
@@ -6363,9 +6364,6 @@ JOIN::make_simple_join(JOIN *parent, TABLE *tmp_table)
DBUG_RETURN(TRUE); /* purecov: inspected */
join_tab= parent->join_tab_reexec;
//psergey2: hopefully this is ok:
// join_tab_ranges.head()->start= join_tab;
// join_tab_ranges.head()->end= join_tab + 1;
top_jtrange_tables= 1;
table= &parent->table_reexec[0]; parent->table_reexec[0]= tmp_table;
@@ -7701,21 +7699,8 @@ make_join_readinfo(JOIN *join, ulonglong options, uint no_jbuf_after)
tab->sorted= sorted;
sorted= 0; // only first must be sorted
//if (sj_is_materialize_strategy(join->best_positions[i].sj_strategy))
if (tab->bush_children) // SJM
if (tab->bush_children)
{
/* This is a start of semi-join nest */
//first_sjm_table= i;
//last_sjm_table= i + join->best_positions[i].n_sj_tables;
/*
psergey2: dont:
if (i == join->const_tables)
join->first_select= sub_select_sjm;
else
tab[-1].next_select= sub_select_sjm;
*/
if (setup_sj_materialization(tab))
return TRUE;
table= tab->table;
@@ -12717,9 +12702,9 @@ do_select(JOIN *join,List<Item> *fields,TABLE *table,Procedure *procedure)
else
{
DBUG_ASSERT(join->tables);
error= join->first_select(join,join_tab,0);
error= sub_select(join,join_tab,0);
if (error == NESTED_LOOP_OK || error == NESTED_LOOP_NO_MORE_ROWS)
error= join->first_select(join,join_tab,1);
error= sub_select(join,join_tab,1);
if (error == NESTED_LOOP_QUERY_LIMIT)
error= NESTED_LOOP_OK; /* select_limit used */
}

19
sql/sql_select.h
View File

@@ -190,8 +190,15 @@ typedef struct st_join_table {
psergey2: for join tabs that are inside a bush: root of this bush.
*/
st_join_table *bush_root_tab;
/* TRUE <=> This join_tab is inside a join bush and is the last leaf tab here */
bool last_leaf_in_bush;
/*
ptr - this is a bush, and ptr points to description of child join_tab
range
NULL - this join tab has no bush children
*/
JOIN_TAB_RANGE *bush_children;
/* Special content for EXPLAIN 'Extra' column or NULL if none */
@@ -500,13 +507,13 @@ protected:
context can be accessed.
*/
JOIN *join;
#if 0
/*
Cardinality of the range of join tables whose fields can be put into the
cache. (A table from the range not necessarily contributes to the cache.)
JOIN_TAB of the first table that can have it's fields in the join cache.
That is, tables in the [start_tab, tab) range can have their fields in the
join cache.
If a join tab in the range represents an SJM-nest, then all tables from the
nest can have their fields in the join cache, too.
*/
uint tables;
#endif
JOIN_TAB *start_tab;
/*
@@ -1505,7 +1512,6 @@ public:
/* We also maintain a stack of join optimization states in * join->positions[] */
/******* Join optimization state members end *******/
Next_select_func first_select;
/*
The cost of best complete join plan found so far during optimization,
after optimization phase - cost of picked join order (not taking into
@@ -1691,7 +1697,6 @@ public:
rollup.state= ROLLUP::STATE_NONE;
no_const_tables= FALSE;
first_select= sub_select;
}
int prepare(Item ***rref_pointer_array, TABLE_LIST *tables, uint wind_num,