MDEV-406: ANALYZE $stmt: add support for BNL join buffering

mysql-test/r/analyze_stmt.result

@@ -79,4 +79,41 @@ analyze select a, a in (select t0.b from t0 where t0.b+1=t1.b+1) from t1 where t
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	r_rows	filtered	r_filtered	Extra
 1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	3	3	100.00	0.00	Using where
 2	DEPENDENT SUBQUERY	t0	ALL	NULL	NULL	NULL	NULL	10	NULL	100.00	NULL	Using where
+drop table t0, t1;
+#
+# Tests for join buffering
+#
+create table t0 (a int, b int);
+insert into t0 values
+(0,0),(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9);
+create table t1 like t0;
+insert into t1 select * from t0;
+explain select * from t0, t1 where t0.a<5 and t1.a<5;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	Using where; Using join buffer (flat, BNL join)
+# These should have filtered=50
+analyze select * from t0, t1 where t0.a<5 and t1.a<5;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	r_rows	filtered	r_filtered	Extra
+1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	10	10	100.00	50.00	Using where
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	10	100.00	50.00	Using where; Using join buffer (flat, BNL join)
+explain select * from t0, t1 where t0.a<5 and t1.b=t0.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	Using where; Using join buffer (flat, BNL join)
+# Now, t1 should have filtered=10
+analyze select * from t0, t1 where t0.a<5 and t1.b=t0.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	r_rows	filtered	r_filtered	Extra
+1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	10	10	100.00	50.00	Using where
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	10	100.00	10.00	Using where; Using join buffer (flat, BNL join)
+explain select * from t0, t1 where t0.a<5 and t1.a<5 and t1.b=t0.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	10	Using where
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	Using where; Using join buffer (flat, BNL join)
+# Now, t1 should have filtered=10
+analyze select * from t0, t1 where t0.a<5 and t1.a<5 and t1.b=t0.b;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	r_rows	filtered	r_filtered	Extra
+1	SIMPLE	t0	ALL	NULL	NULL	NULL	NULL	10	10	100.00	50.00	Using where
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	10	10	100.00	10.00	Using where; Using join buffer (flat, BNL join)
 drop table t0,t1;
+# TODO: Check what is counted for "range checked for each record".

mysql-test/t/analyze_stmt.test

@@ -61,5 +61,30 @@ analyze select a, a in (select t0.b from t0 where t0.b+1=t1.b+1) from t1;
 --echo # Try a subquery that is never executed
 analyze select a, a in (select t0.b from t0 where t0.b+1=t1.b+1) from t1 where t1.a > 5;
 
+drop table t0, t1;
+
+--echo #
+--echo # Tests for join buffering
+--echo #
+create table t0 (a int, b int);
+insert into t0 values
+  (0,0),(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9);
+create table t1 like t0;
+insert into t1 select * from t0;
+
+explain select * from t0, t1 where t0.a<5 and t1.a<5;
+--echo # These should have filtered=50
+analyze select * from t0, t1 where t0.a<5 and t1.a<5;
+
+explain select * from t0, t1 where t0.a<5 and t1.b=t0.b;
+--echo # Now, t1 should have filtered=10
+analyze select * from t0, t1 where t0.a<5 and t1.b=t0.b;
+
+explain select * from t0, t1 where t0.a<5 and t1.a<5 and t1.b=t0.b;
+--echo # Now, t1 should have filtered=10
+analyze select * from t0, t1 where t0.a<5 and t1.a<5 and t1.b=t0.b;
+
 drop table t0,t1;
 
+--echo # TODO: Check what is counted for "range checked for each record".
+

sql/sql_explain.cc

@@ -585,12 +585,10 @@ int Explain_table_access::print_explain(select_result_sink *output, uint8 explai
     }
     else
     {
-      double r_filtered;
-      if (tracker.r_rows > 0)
-        r_filtered= 100.0 * (double)tracker.r_rows_after_table_cond / tracker.r_rows;
-      else
-        r_filtered= 100.0;
-      item_list.push_back(new Item_float(r_filtered, 2));
+      double r_filtered= tracker.get_filtered_after_where();
+      if (bka_type.is_using_jbuf())
+        r_filtered *= jbuf_tracker.get_filtered_after_where();
+      item_list.push_back(new Item_float(r_filtered*100.0, 2));
     }
   }
 

sql/sql_explain.h

@@ -19,13 +19,13 @@ class Table_access_tracker
 {
 public:
   Table_access_tracker() :
-    r_scans(0), r_rows(0), r_rows_after_table_cond(0),
+    r_scans(0), r_rows(0), /*r_rows_after_table_cond(0),*/
     r_rows_after_where(0)
   {}
 
   ha_rows r_scans; /* How many scans were ran on this join_tab */
   ha_rows r_rows; /* How many rows we've got after that */
-  ha_rows r_rows_after_table_cond; /* Rows after applying the table condition */
+//  ha_rows r_rows_after_table_cond; /* Rows after applying the table condition */
   ha_rows r_rows_after_where; /* Rows after applying attached part of WHERE */
 
   bool has_scans() { return (r_scans != 0); }
@@ -33,6 +33,17 @@ class Table_access_tracker
   {
     return r_scans ? (ha_rows)rint((double) r_rows / r_scans): 0;
   }
+
+  double get_filtered_after_where()
+  {
+    double r_filtered;
+    if (r_rows > 0)
+      r_filtered= (double)r_rows_after_where / r_rows;
+    else
+      r_filtered= 1.0;
+
+    return r_filtered;
+  }
 };
 
 
@@ -371,13 +382,17 @@ enum explain_extra_tag
 };
 
 
-typedef struct st_explain_bka_type
+class EXPLAIN_BKA_TYPE
 {
+public:
+  EXPLAIN_BKA_TYPE() : join_alg(NULL) {}
+
   bool incremental;
   const char *join_alg;
   StringBuffer<64> mrr_type;
-
-} EXPLAIN_BKA_TYPE;
+  
+  bool is_using_jbuf() { return (join_alg != NULL); }
+};
 
 
 /*
@@ -517,6 +532,7 @@ class Explain_table_access : public Sql_alloc
 
   /* ANALYZE members*/
   Table_access_tracker tracker;
+  Table_access_tracker jbuf_tracker;
 
 private:
   void append_tag_name(String *str, enum explain_extra_tag tag);

sql/sql_join_cache.cc

@@ -2254,7 +2254,7 @@ enum_nested_loop_state JOIN_CACHE::join_matching_records(bool skip_last)
     */
     goto finish;
   }
-  
+
   while (!(error= join_tab_scan->next()))   
   {
     if (join->thd->check_killed())
@@ -2271,11 +2271,13 @@ enum_nested_loop_state JOIN_CACHE::join_matching_records(bool skip_last)
     /* Prepare to read matching candidates from the join buffer */
     if (prepare_look_for_matches(skip_last))
       continue;
+    join_tab->jbuf_tracker->r_scans++;
 
     uchar *rec_ptr;
     /* Read each possible candidate from the buffer and look for matches */
     while ((rec_ptr= get_next_candidate_for_match()))
-    { 
+    {
+      join_tab->jbuf_tracker->r_rows++;
       /* 
         If only the first match is needed, and, it has been already found for
         the next record read from the join buffer, then the record is skipped.
@@ -2445,6 +2447,8 @@ inline bool JOIN_CACHE::check_match(uchar *rec_ptr)
 
   if (join_tab->select && join_tab->select->skip_record(join->thd) <= 0)
     DBUG_RETURN(FALSE);
+  
+  join_tab->jbuf_tracker->r_rows_after_where++;
 
   if (!join_tab->is_last_inner_table())
     DBUG_RETURN(TRUE);
@@ -2568,7 +2572,7 @@ enum_nested_loop_state JOIN_CACHE::join_null_complements(bool skip_last)
     none
 */ 
 
-void JOIN_CACHE::save_explain_data(struct st_explain_bka_type *explain)
+void JOIN_CACHE::save_explain_data(EXPLAIN_BKA_TYPE *explain)
 {
   explain->incremental= MY_TEST(prev_cache);
 
@@ -2613,14 +2617,14 @@ static void add_mrr_explain_info(String *str, uint mrr_mode, handler *file)
   }
 }
 
-void JOIN_CACHE_BKA::save_explain_data(struct st_explain_bka_type *explain)
+void JOIN_CACHE_BKA::save_explain_data(EXPLAIN_BKA_TYPE *explain)
 {
   JOIN_CACHE::save_explain_data(explain); 
   add_mrr_explain_info(&explain->mrr_type, mrr_mode, join_tab->table->file);
 }
 
 
-void JOIN_CACHE_BKAH::save_explain_data(struct st_explain_bka_type *explain)
+void JOIN_CACHE_BKAH::save_explain_data(EXPLAIN_BKA_TYPE *explain)
 {
   JOIN_CACHE::save_explain_data(explain); 
   add_mrr_explain_info(&explain->mrr_type, mrr_mode, join_tab->table->file);
@@ -3326,6 +3330,7 @@ int JOIN_TAB_SCAN::open()
 {
   save_or_restore_used_tabs(join_tab, FALSE);
   is_first_record= TRUE;
+  join_tab->tracker->r_scans++;
   return join_init_read_record(join_tab);
 }
 
@@ -3364,8 +3369,14 @@ int JOIN_TAB_SCAN::next()
     is_first_record= FALSE;
   else
     err= info->read_record(info);
-  if (!err && table->vfield)
-    update_virtual_fields(thd, table);
+
+  if (!err)
+  {
+    join_tab->tracker->r_rows++;
+    if (table->vfield)
+      update_virtual_fields(thd, table);
+  }
+
   while (!err && select && (skip_rc= select->skip_record(thd)) <= 0)
   {
     if (thd->check_killed() || skip_rc < 0) 
@@ -3375,9 +3386,16 @@ int JOIN_TAB_SCAN::next()
       meet the condition pushed to the table join_tab.
     */
     err= info->read_record(info);
-    if (!err && table->vfield)
-      update_virtual_fields(thd, table);
-  } 
+    if (!err)
+    {
+      join_tab->tracker->r_rows++;
+      if (table->vfield)
+        update_virtual_fields(thd, table);
+    }
+  }
+
+  if (!err)
+    join_tab->tracker->r_rows_after_where++;
   return err; 
 }
 

sql/sql_join_cache.h

@@ -63,7 +63,7 @@ typedef struct st_cache_field {
 
 class JOIN_TAB_SCAN;
 
-struct st_explain_bka_type;
+class EXPLAIN_BKA_TYPE;
 
 /*
   JOIN_CACHE is the base class to support the implementations of 
@@ -659,7 +659,7 @@ class JOIN_CACHE :public Sql_alloc
   enum_nested_loop_state join_records(bool skip_last);
 
   /* Add a comment on the join algorithm employed by the join cache */
-  virtual void save_explain_data(struct st_explain_bka_type *explain);
+  virtual void save_explain_data(EXPLAIN_BKA_TYPE *explain);
 
   THD *thd();
 
@@ -1337,7 +1337,7 @@ class JOIN_CACHE_BKA :public JOIN_CACHE
   /* Check index condition of the joined table for a record from BKA cache */
   bool skip_index_tuple(range_id_t range_info);
 
-  void save_explain_data(struct st_explain_bka_type *explain);
+  void save_explain_data(EXPLAIN_BKA_TYPE *explain);
 };
 
 
@@ -1428,5 +1428,5 @@ class JOIN_CACHE_BKAH :public JOIN_CACHE_BNLH
   /* Check index condition of the joined table for a record from BKAH cache */
   bool skip_index_tuple(range_id_t range_info);
 
-  void save_explain_data(struct st_explain_bka_type *explain);
+  void save_explain_data(EXPLAIN_BKA_TYPE *explain);
 };

sql/sql_select.cc

@@ -17731,7 +17731,7 @@ evaluate_join_record(JOIN *join, JOIN_TAB *join_tab,
       There is no select condition or the attached pushed down
       condition is true => a match is found.
     */
-    join_tab->tracker->r_rows_after_table_cond++;
+    join_tab->tracker->r_rows_after_where++;
     bool found= 1;
     while (join_tab->first_unmatched && found)
     {
@@ -23308,6 +23308,7 @@ void JOIN_TAB::save_explain_data(Explain_table_access *eta, table_map prefix_tab
   eta->quick_info= NULL;
   
   tab->tracker= &eta->tracker;
+  tab->jbuf_tracker= &eta->jbuf_tracker;
   
   /* id */
   if (tab->bush_root_tab)

sql/sql_select.h

@@ -252,6 +252,7 @@ typedef struct st_join_table {
   enum explain_extra_tag info;
   
   Table_access_tracker *tracker;
+  Table_access_tracker *jbuf_tracker;
   /* 
     Bitmap of TAB_INFO_* bits that encodes special line for EXPLAIN 'Extra'
     column, or 0 if there is no info.