made variable query_cache_min_res_unit from QUERY_CACHE_MIN_RESULT_DATA_SIZE (SCRUM)

mysql-test/r/query_cache.result

@@ -497,6 +497,65 @@ drop table t1;
 show status like "Qcache_queries_in_cache";
 Variable_name	Value
 Qcache_queries_in_cache	0
+show global variables like "query_cache_min_res_unit";
+Variable_name	Value
+query_cache_min_res_unit	4096
+set GLOBAL query_cache_min_res_unit=1001;
+show global variables like "query_cache_min_res_unit";
+Variable_name	Value
+query_cache_min_res_unit	1008
+create table t1 (a int not null);
+insert into t1 values (1),(2),(3);
+create table t2 (a int not null);
+insert into t2 values (1),(2),(3);
+select * from t1;
+a
+1
+2
+3
+select * from t1;
+a
+1
+2
+3
+select * from t2;
+a
+1
+2
+3
+select * from t2;
+a
+1
+2
+3
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	11
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	2
+drop table t1;
+select a from t2;
+a
+1
+2
+3
+select a from t2;
+a
+1
+2
+3
+show status like "Qcache_hits";
+Variable_name	Value
+Qcache_hits	12
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	2
+drop table t2;
+set GLOBAL query_cache_min_res_unit=default;
+show global variables like "query_cache_min_res_unit";
+Variable_name	Value
+query_cache_min_res_unit	4096
 set GLOBAL query_cache_size=1000;
 show global variables like "query_cache_size";
 Variable_name	Value

mysql-test/t/query_cache.test

@@ -342,6 +342,31 @@ show status like "Qcache_queries_in_cache";
 drop table t1;
 show status like "Qcache_queries_in_cache";
 
+#
+# Test of min result data unit size changing
+#
+show global variables like "query_cache_min_res_unit";
+set GLOBAL query_cache_min_res_unit=1001;
+show global variables like "query_cache_min_res_unit";
+create table t1 (a int not null);
+insert into t1 values (1),(2),(3);
+create table t2 (a int not null);
+insert into t2 values (1),(2),(3);
+select * from t1;
+select * from t1;
+select * from t2;
+select * from t2;
+show status like "Qcache_hits";
+show status like "Qcache_queries_in_cache";
+drop table t1;
+select a from t2;
+select a from t2;
+show status like "Qcache_hits";
+show status like "Qcache_queries_in_cache";
+drop table t2;
+set GLOBAL query_cache_min_res_unit=default;
+show global variables like "query_cache_min_res_unit";
+
 #
 # Test of query cache resizing
 #

sql/mysql_priv.h

@@ -307,6 +307,7 @@ typedef compare_func_creator (*chooser_compare_func_creator)(bool invert);
 #define query_cache_destroy() query_cache.destroy()
 #define query_cache_result_size_limit(A) query_cache.result_size_limit(A)
 #define query_cache_resize(A) query_cache.resize(A)
+#define query_cache_set_min_res_unit(A) query_cache.set_min_res_unit(A)
 #define query_cache_invalidate3(A, B, C) query_cache.invalidate(A, B, C)
 #define query_cache_invalidate1(A) query_cache.invalidate(A)
 #define query_cache_send_result_to_client(A, B, C) \
@@ -318,6 +319,7 @@ typedef compare_func_creator (*chooser_compare_func_creator)(bool invert);
 #define query_cache_destroy()
 #define query_cache_result_size_limit(A)
 #define query_cache_resize(A)
+#define query_cache_set_min_res_unit(A)
 #define query_cache_invalidate3(A, B, C)
 #define query_cache_invalidate1(A)
 #define query_cache_send_result_to_client(A, B, C) 0
@@ -699,7 +701,8 @@ extern ulong filesort_rows, filesort_range_count, filesort_scan_count;
 extern ulong filesort_merge_passes;
 extern ulong select_range_check_count, select_range_count, select_scan_count;
 extern ulong select_full_range_join_count,select_full_join_count;
-extern ulong slave_open_temp_tables, query_cache_size;
+extern ulong slave_open_temp_tables;
+extern ulong query_cache_size, query_cache_min_res_unit;
 extern ulong thd_startup_options, slow_launch_threads, slow_launch_time;
 extern ulong server_id, concurrency;
 extern ulong ha_read_count, ha_write_count, ha_delete_count, ha_update_count;

sql/mysqld.cc

@@ -363,7 +363,8 @@ ulong slave_net_timeout;
 ulong thread_cache_size=0, binlog_cache_size=0, max_binlog_cache_size=0;
 ulong query_cache_size=0;
 #ifdef HAVE_QUERY_CACHE
-ulong query_cache_limit=0;
+ulong query_cache_limit= 0;
+ulong query_cache_min_res_unit= QUERY_CACHE_MIN_RESULT_DATA_SIZE;
 Query_cache query_cache;
 #endif
 arg_cmp_func Arg_comparator::comparator_matrix[4][2] =
@@ -2148,6 +2149,7 @@ static int init_server_components()
   table_cache_init();
   hostname_cache_init();
   query_cache_result_size_limit(query_cache_limit);
+  query_cache_set_min_res_unit(query_cache_min_res_unit);
   query_cache_resize(query_cache_size);
   randominit(&sql_rand,(ulong) start_time,(ulong) start_time/2);
   reset_floating_point_exceptions();
@@ -3443,7 +3445,7 @@ enum options
   OPT_NET_BUFFER_LENGTH, OPT_NET_RETRY_COUNT,
   OPT_NET_READ_TIMEOUT, OPT_NET_WRITE_TIMEOUT,
   OPT_OPEN_FILES_LIMIT,
-  OPT_QUERY_CACHE_LIMIT, OPT_QUERY_CACHE_SIZE,
+  OPT_QUERY_CACHE_LIMIT, OPT_QUERY_CACHE_MIN_RES_UNIT, OPT_QUERY_CACHE_SIZE,
   OPT_QUERY_CACHE_TYPE, OPT_RECORD_BUFFER,
   OPT_RECORD_RND_BUFFER, OPT_RELAY_LOG_SPACE_LIMIT,
   OPT_SLAVE_NET_TIMEOUT, OPT_SLAVE_COMPRESSED_PROTOCOL, OPT_SLOW_LAUNCH_TIME,
@@ -4206,6 +4208,11 @@ struct my_option my_long_options[] =
    "Don't cache results that are bigger than this.",
    (gptr*) &query_cache_limit, (gptr*) &query_cache_limit, 0, GET_ULONG,
    REQUIRED_ARG, 1024*1024L, 0, (longlong) ULONG_MAX, 0, 1, 0},
+  {"query_cache_min_res_unit", OPT_QUERY_CACHE_MIN_RES_UNIT,
+   "minimal size of unit in wich space for results is allocated (last unit will be trimed after writing all result data.",
+   (gptr*) &query_cache_min_res_unit, (gptr*) &query_cache_min_res_unit,
+   0, GET_ULONG, REQUIRED_ARG, QUERY_CACHE_MIN_RESULT_DATA_SIZE,
+   0, (longlong) ULONG_MAX, 0, 1, 0},
 #endif /*HAVE_QUERY_CACHE*/
   {"query_cache_size", OPT_QUERY_CACHE_SIZE,
    "The memory allocated to store results from old queries.",

sql/set_var.cc

@@ -85,6 +85,7 @@ static void fix_net_write_timeout(THD *thd, enum_var_type type);
 static void fix_net_retry_count(THD *thd, enum_var_type type);
 static void fix_max_join_size(THD *thd, enum_var_type type);
 static void fix_query_cache_size(THD *thd, enum_var_type type);
+static void fix_query_cache_min_res_unit(THD *thd, enum_var_type type);
 static void fix_key_buffer_size(THD *thd, enum_var_type type);
 static byte *get_error_count(THD *thd);
 static byte *get_warning_count(THD *thd);
@@ -204,6 +205,9 @@ sys_var_long_ptr	sys_query_cache_size("query_cache_size",
 #ifdef HAVE_QUERY_CACHE
 sys_var_long_ptr	sys_query_cache_limit("query_cache_limit",
 					      &query_cache.query_cache_limit);
+sys_var_long_ptr        sys_query_cache_min_res_unit("query_cache_min_res_unit",
+						     &query_cache_min_res_unit,
+						     fix_query_cache_min_res_unit);
 sys_var_thd_enum	sys_query_cache_type("query_cache_type",
 					     &SV::query_cache_type,
 					     &query_cache_type_typelib);
@@ -384,6 +388,7 @@ sys_var *sys_variables[]=
   &sys_query_cache_size,
 #ifdef HAVE_QUERY_CACHE
   &sys_query_cache_limit,
+  &sys_query_cache_min_res_unit,
   &sys_query_cache_type,
 #endif /* HAVE_QUERY_CACHE */
   &sys_quote_show_create,
@@ -546,6 +551,8 @@ struct show_var_st init_vars[]= {
   {sys_rpl_recovery_rank.name,(char*) &sys_rpl_recovery_rank,       SHOW_SYS},
 #ifdef HAVE_QUERY_CACHE
   {sys_query_cache_limit.name,(char*) &sys_query_cache_limit,	    SHOW_SYS},
+  {sys_query_cache_min_res_unit.name, (char*) &sys_query_cache_min_res_unit,
+   SHOW_SYS},
   {sys_query_cache_size.name, (char*) &sys_query_cache_size,	    SHOW_SYS},
   {sys_query_cache_type.name, (char*) &sys_query_cache_type,        SHOW_SYS},
 #endif /* HAVE_QUERY_CACHE */
@@ -696,6 +703,15 @@ static void fix_query_cache_size(THD *thd, enum_var_type type)
 }
 
 
+#ifdef HAVE_QUERY_CACHE
+static void fix_query_cache_min_res_unit(THD *thd, enum_var_type type)
+{
+  query_cache_min_res_unit= 
+    query_cache.set_min_res_unit(query_cache_min_res_unit);
+}
+#endif
+
+
 static void fix_key_buffer_size(THD *thd, enum_var_type type)
 {
   ha_resize_key_cache();

sql/sql_cache.cc

@@ -743,6 +743,14 @@ ulong Query_cache::resize(ulong query_cache_size_arg)
 }
 
 
+ulong Query_cache::set_min_res_unit(ulong size)
+{
+  if (size < min_allocation_unit)
+    size= min_allocation_unit;
+  return (min_result_data_size= ALIGN_SIZE(size));
+}
+
+
 void Query_cache::store_query(THD *thd, TABLE_LIST *tables_used)
 {
   TABLE_COUNTER_TYPE local_tables;

sql/sql_cache.h

@@ -345,7 +345,10 @@ protected:
 
   /* resize query cache (return real query size, 0 if disabled) */
   ulong resize(ulong query_cache_size);
+  /* set limit on result size */
   inline void result_size_limit(ulong limit){query_cache_limit=limit;}
+  /* set minimal result data allocation unit size */
+  ulong set_min_res_unit(ulong size);
 
   /* register query in cache */
   void store_query(THD *thd, TABLE_LIST *used_tables);