dict0mem.c, dict0dict.c, row0mysql.c, dict0mem.h:

  Do less statistics calculations for tables
dict0mem.h, row0mysql.c:
  Make calculation of new statistics less frequent, because the statistics in 3.23.44 involves many random disk reads

innobase/dict/dict0dict.c

@@ -455,7 +455,7 @@ dict_table_get(
 	mutex_exit(&(dict_sys->mutex));
 
 	if (table != NULL) {
-		if (table->stat_last_estimate_counter == (ulint)(-1)) {
+	        if (!table->stat_initialized) {
 			dict_update_statistics(table);
 		}
 	}
@@ -2578,6 +2578,8 @@ dict_update_statistics_low(
 	ulint		size;
 	ulint		sum_of_index_sizes	= 0;
 
+	printf("Updating statistics for table %s\n", table->name);
+
 	/* Find out the sizes of the indexes and how many different values
 	for the key they approximately have */
 
@@ -2614,7 +2616,9 @@ dict_update_statistics_low(
 	table->stat_sum_of_other_index_sizes = sum_of_index_sizes
 						- index->stat_index_size;
 
-	table->stat_last_estimate_counter = table->stat_modif_counter;
+	table->stat_initialized = TRUE;
+
+        table->stat_modified_counter = 0;
 }
 
 /*************************************************************************

innobase/dict/dict0mem.c

@@ -73,9 +73,9 @@ dict_mem_table_create(
 
 	table->does_not_fit_in_memory = FALSE;
 
-	table->stat_last_estimate_counter = (ulint)(-1);
+	table->stat_initialized = FALSE;
 
-	table->stat_modif_counter = 0;
+	table->stat_modified_counter = 0;
 	
 	mutex_create(&(table->autoinc_mutex));
 	mutex_set_level(&(table->autoinc_mutex), SYNC_DICT_AUTOINC_MUTEX);

innobase/include/dict0mem.h

@@ -348,20 +348,20 @@ struct dict_table_struct{
 				database pages */
 	ulint		stat_sum_of_other_index_sizes;
 				/* other indexes in database pages */
-	ulint		stat_last_estimate_counter;
-				/* when the estimates were last time
-				calculated; a value (ulint)-1 denotes that
-				they have not yet been calculated for this
-				table (or the counter has wrapped over) */
-	ulint		stat_modif_counter;
+	ibool           stat_initialized; /* TRUE if statistics have
+				been calculated the first time
+			        after database startup or table creation */
+	ulint		stat_modified_counter;
 				/* when a row is inserted, updated, or deleted,
 				we add the row length to this number; we
 				calculate new estimates for the stat_...
 				values for the table and the indexes at an
-				interval of DICT_STAT_CALCULATE_INTERVAL,
-				but for small tables more often, also
+				interval of 2 GB or when about 1 / 16 of table
+				has been modified; also
 				when the estimate operation is called
-				for MySQL SHOW TABLE STATUS; this counter
+				for MySQL SHOW TABLE STATUS; the counter is
+				reset to zero at statistics calculation;
+				this counter
 				is not protected by any latch, because this
 				is only used for heuristics */
 	/*----------------------*/
@@ -378,10 +378,6 @@ struct dict_table_struct{
 };
 #define	DICT_TABLE_MAGIC_N	76333786
 					
-/* Statistics are calculated at least with this interval; see the struct
-above */
-#define DICT_STAT_CALCULATE_INTERVAL	(UNIV_PAGE_SIZE * 8)
-					
 /* Data structure for a stored procedure */
 struct dict_proc_struct{
 	mem_heap_t*	heap;	/* memory heap */

innobase/row/row0mysql.c

@@ -432,19 +432,24 @@ row_update_statistics_if_needed(
 	row_prebuilt_t*	prebuilt)	/* in: prebuilt struct */
 {
 	ulint	counter;
-	ulint	old_counter;
 	
-	counter = prebuilt->table->stat_modif_counter;
+	counter = prebuilt->table->stat_modified_counter;
 
-	counter += prebuilt->mysql_row_len;
-	prebuilt->table->stat_modif_counter = counter;
+	/* Since the physical size of an InnoDB row is bigger than the
+	MySQL row len, we put a safety factor 2 below */
 
-	old_counter = prebuilt->table->stat_last_estimate_counter;
+	counter += 2 * prebuilt->mysql_row_len;
 
-	if (counter - old_counter >= DICT_STAT_CALCULATE_INTERVAL
-	    || counter - old_counter >=
-		(UNIV_PAGE_SIZE
-			* prebuilt->table->stat_clustered_index_size / 2)) {
+	prebuilt->table->stat_modified_counter = counter;
+
+	/* Calculate new statistics if 1 / 16 of table has been modified
+	since the last time a statistics batch was run, or if
+	stat_modified_counter > 2 000 000 000 (to avoid wrap-around) */
+
+	if (counter > 2000000000
+	    || ((ib_longlong)counter >
+		(UNIV_PAGE_SIZE * prebuilt->table->stat_clustered_index_size)
+		/ 16)) {
 
 		dict_update_statistics(prebuilt->table);
 	}	
@@ -1019,6 +1024,26 @@ row_create_table_for_mysql(
 		os_event_set(srv_lock_timeout_thread_event);
 	}
 
+	keywordlen = ut_strlen("innodb_mem_validate");
+
+	if (namelen >= keywordlen
+		    && 0 == ut_memcmp(table->name + namelen - keywordlen,
+ 				"innodb_mem_validate", keywordlen)) {
+
+	        /* We define here a debugging feature intended for
+		developers */
+
+	        printf("Validating InnoDB memory:\n"
+		 "to use this feature you must compile InnoDB with\n"
+		 "UNIV_MEM_DEBUG defined in univ.i and the server must be\n"
+		 "quiet because allocation from a mem heap is not protected\n"
+		       "by any semaphore.\n");
+
+		ut_a(mem_validate());
+		      
+		printf("Memory validated\n");
+	}
+
 	/* Serialize data dictionary operations with dictionary mutex:
 	no deadlocks can occur then in these operations */