Fix for BUG#43660- SHOW INDEXES/ANALYZE does NOT update cardinality

                   for indexes of InnoDB table

Fixes by replacing the PRNG that is used to pick random pages with a 
better one. 

Also adds a configuration option "innodb_use_legacy_cardinality_algorithm"
to enable the fix only when the option is set.

This patch is from http://bugs.mysql.com/file.php?id=11789

3 files changed, 21 insertions, 1 deletions

diff --git a/sql/ha_innodb.h b/sql/ha_innodb.h
index 3db983901b3..e27fb89d014 100644
--- a/sql/ha_innodb.h
+++ b/sql/ha_innodb.h
@@ -234,6 +234,11 @@ extern ulong srv_thread_sleep_delay;
 extern ulong srv_thread_concurrency;
 extern ulong srv_commit_concurrency;
 extern ulong srv_flush_log_at_trx_commit;
+/* An option to enable the fix for "Bug#43660 SHOW INDEXES/ANALYZE does
+NOT update cardinality for indexes of InnoDB table". By default we are
+running with the fix disabled because MySQL 5.1 is frozen for such
+behavioral changes. */
+extern char srv_use_legacy_cardinality_algorithm;
 }
 
 bool innobase_init(void);
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index ad3521e5dde..0583e3fa57f 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -5044,7 +5044,8 @@ enum options_mysqld
   OPT_SECURE_FILE_PRIV,
   OPT_KEEP_FILES_ON_CREATE,
   OPT_INNODB_ADAPTIVE_HASH_INDEX,
-  OPT_FEDERATED
+  OPT_FEDERATED,
+  OPT_INNODB_USE_LEGACY_CARDINALITY_ALGORITHM
 };
 
 
@@ -5351,6 +5352,14 @@ Disable with --skip-innodb-doublewrite.", (gptr*) &innobase_use_doublewrite,
    (gptr*) &global_system_variables.innodb_table_locks,
    (gptr*) &global_system_variables.innodb_table_locks,
    0, GET_BOOL, OPT_ARG, 1, 0, 0, 0, 0, 0},
+  {"innodb_use_legacy_cardinality_algorithm", 
+   OPT_INNODB_USE_LEGACY_CARDINALITY_ALGORITHM,
+   "Use legacy algorithm for picking random pages during index cardinality "
+   "estimation. Disable this to use a better algorithm, but note that your "
+   "query plans may change (enabled by default).",
+   (gptr*) &srv_use_legacy_cardinality_algorithm,
+   (gptr*) &srv_use_legacy_cardinality_algorithm,
+   0, GET_BOOL, OPT_ARG, 1, 0, 0, 0, 0, 0},
 #endif /* End HAVE_INNOBASE_DB */
   {"isam", OPT_ISAM, "Obsolete. ISAM storage engine is no longer supported.",
    (gptr*) &opt_isam, (gptr*) &opt_isam, 0, GET_BOOL, NO_ARG, 0, 0, 0,
diff --git a/sql/set_var.cc b/sql/set_var.cc
index 735bb5279bd..14ec2e57aab 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -450,6 +450,9 @@ sys_var_thd_bool	sys_innodb_table_locks("innodb_table_locks",
                                                &SV::innodb_table_locks);
 sys_var_thd_bool	sys_innodb_support_xa("innodb_support_xa",
                                                &SV::innodb_support_xa);
+sys_var_bool_ptr        sys_innodb_use_legacy_cardinality_algorithm(
+                          "innodb_use_legacy_cardinality_algorithm",
+                          &srv_use_legacy_cardinality_algorithm);
 sys_var_long_ptr	sys_innodb_autoextend_increment("innodb_autoextend_increment",
 							&srv_auto_extend_increment);
 sys_var_long_ptr	sys_innodb_sync_spin_loops("innodb_sync_spin_loops",
@@ -804,6 +807,7 @@ sys_var *sys_variables[]=
   &sys_innodb_max_purge_lag,
   &sys_innodb_table_locks,
   &sys_innodb_support_xa,
+  &sys_innodb_use_legacy_cardinality_algorithm,
   &sys_innodb_autoextend_increment,
   &sys_innodb_sync_spin_loops,
   &sys_innodb_concurrency_tickets,
@@ -946,6 +950,8 @@ struct show_var_st init_vars[]= {
   {sys_innodb_table_locks.name, (char*) &sys_innodb_table_locks, SHOW_SYS},
   {sys_innodb_thread_concurrency.name, (char*) &sys_innodb_thread_concurrency, SHOW_SYS},
   {sys_innodb_thread_sleep_delay.name, (char*) &sys_innodb_thread_sleep_delay, SHOW_SYS},
+  {sys_innodb_use_legacy_cardinality_algorithm.name,
+   (char*) &sys_innodb_use_legacy_cardinality_algorithm, SHOW_SYS},
 #endif
   {sys_interactive_timeout.name,(char*) &sys_interactive_timeout,   SHOW_SYS},
   {sys_join_buffer_size.name,   (char*) &sys_join_buffer_size,	    SHOW_SYS},