BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index

statistics (like 4.0 did) (patch #3, with review #1 & #2 feedback addressed)


include/myisam.h:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics
myisam/mi_check.c:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics
myisam/myisamchk.c:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics
mysql-test/r/myisam.result:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics
mysql-test/t/myisam.test:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics
sql/ha_myisam.cc:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics
sql/handler.h:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics
sql/mysqld.cc:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics
sql/set_var.cc:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics
sql/sql_class.h:
  BUG#12232: Add a server option to treat NULL values as equal when calculating MyISAM index statistics

1 files changed, 26 insertions, 1 deletions

diff --git a/myisam/myisamchk.c b/myisam/myisamchk.c
index 3b9742b79fb..1a7d2b2d9a8 100644
--- a/myisam/myisamchk.c
+++ b/myisam/myisamchk.c
@@ -67,6 +67,7 @@ static const char *field_pack[]=
  "no zeros", "blob", "constant", "table-lockup",
  "always zero","varchar","unique-hash","?","?"};
 
+static const char *myisam_stats_method_str="nulls_inequal";
 
 static void get_options(int *argc,char * * *argv);
 static void print_version(void);
@@ -155,7 +156,7 @@ enum options_mc {
   OPT_READ_BUFFER_SIZE, OPT_WRITE_BUFFER_SIZE, OPT_SORT_BUFFER_SIZE,
   OPT_SORT_KEY_BLOCKS, OPT_DECODE_BITS, OPT_FT_MIN_WORD_LEN,
   OPT_FT_MAX_WORD_LEN, OPT_FT_STOPWORD_FILE,
-  OPT_MAX_RECORD_LENGTH, OPT_AUTO_CLOSE
+  OPT_MAX_RECORD_LENGTH, OPT_AUTO_CLOSE, OPT_STATS_METHOD
 };
 
 static struct my_option my_long_options[] =
@@ -336,6 +337,11 @@ static struct my_option my_long_options[] =
     "Use stopwords from this file instead of built-in list.",
     (gptr*) &ft_stopword_file, (gptr*) &ft_stopword_file, 0, GET_STR,
     REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
+  {"stats_method", OPT_STATS_METHOD,
+   "Specifies how index statistics collection code should threat NULLs. "
+   "Possible values of name are \"nulls_inequal\" (default behavior for 4.1/5.0), and \"nulls_equal\" (emulate 4.0 behavior).",
+   (gptr*) &myisam_stats_method_str, (gptr*) &myisam_stats_method_str, 0,
+    GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   { 0, 0, 0, 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0}
 };
 
@@ -465,6 +471,12 @@ static void usage(void)
 
 #include <help_end.h>
 
+const char *myisam_stats_method_names[] = {"nulls_inequal", "nulls_equal",
+                                           NullS};
+TYPELIB myisam_stats_method_typelib= {
+  array_elements(myisam_stats_method_names) - 1, "",
+  myisam_stats_method_names, NULL};
+
 	 /* Read options */
 
 static my_bool
@@ -684,6 +696,19 @@ get_one_option(int optid,
     else
       check_param.testflag|= T_CALC_CHECKSUM;
     break;
+  case OPT_STATS_METHOD:
+  {
+    myisam_stats_method_str= argument;
+    int method;
+    if ((method=find_type(argument, &myisam_stats_method_typelib, 2)) <= 0)
+    {
+      fprintf(stderr, "Invalid value of stats_method: %s.\n", argument);
+      exit(1);
+    }
+    check_param.stats_method= test(method-1)? MI_STATS_METHOD_NULLS_EQUAL :
+                                              MI_STATS_METHOD_NULLS_NOT_EQUAL;
+    break;
+  }
 #ifdef DEBUG					/* Only useful if debugging */
   case OPT_START_CHECK_POS:
     check_param.start_check_pos= strtoull(argument, NULL, 0);