MDEV-21472: ALTER TABLE ... ANALYZE PARTITION ... with EITS reads and locks all rows

Do not collect EITS statistics for this statement:

  ALTER TABLE t ANALYZE PARTITION p

EITS stats are currently global, not per-partition.
Collecting global stats when we are asked to process just one partition
causes issues for DBAs.

4 files changed, 71 insertions, 4 deletions

diff --git a/mysql-test/r/stat_tables_partition.result b/mysql-test/r/stat_tables_partition.result
index 12ae2570272..2dd63e858d4 100644
--- a/mysql-test/r/stat_tables_partition.result
+++ b/mysql-test/r/stat_tables_partition.result
@@ -9,5 +9,37 @@ ANALYZE TABLE t1;
 Table	Op	Msg_type	Msg_text
 test.t1	analyze	status	Engine-independent statistics collected
 test.t1	analyze	status	OK
-SET use_stat_tables = DEFAULT;
 DROP TABLE t1;
+#
+# MDEV-21472: ALTER TABLE ... ANALYZE PARTITION ... with EITS reads and locks all rows
+#
+CREATE TABLE t1 (
+id int(11) auto_increment primary key,
+c1 int(11) DEFAULT NULL
+) PARTITION BY RANGE (id) (
+PARTITION p0 VALUES LESS THAN (4),
+PARTITION p1 VALUES LESS THAN MAXVALUE
+);
+insert into t1(c1) values (1),(1),(1),(1),  (1),(1),(1),(1);
+insert into t1(c1) select c1 from t1;
+insert into t1(c1) select c1 from t1;
+select count(*) from t1;
+count(*)
+32
+select count(*) from t1 where id <4;
+count(*)
+3
+flush status;
+set session use_stat_tables='preferably';
+# Must NOT show "Engine-independent statistics collected":
+alter table t1 analyze partition p0;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+# Should not have Handler_read_rnd_next=34
+show session status like 'Handler_read_rnd%';
+Variable_name	Value
+Handler_read_rnd	0
+Handler_read_rnd_deleted	0
+Handler_read_rnd_next	0
+drop table t1;
+SET use_stat_tables = DEFAULT;
diff --git a/mysql-test/r/stat_tables_rbr.result b/mysql-test/r/stat_tables_rbr.result
index 35e74e29b08..83f8e3bb7c6 100644
--- a/mysql-test/r/stat_tables_rbr.result
+++ b/mysql-test/r/stat_tables_rbr.result
@@ -13,7 +13,6 @@ SET use_stat_tables = PREFERABLY;
 CREATE TABLE t1 ( a INT ) ENGINE=MyISAM PARTITION BY HASH(a) PARTITIONS 2;
 ALTER TABLE t1 ANALYZE PARTITION p1;
 Table	Op	Msg_type	Msg_text
-test.t1	analyze	status	Engine-independent statistics collected
 test.t1	analyze	status	OK
 include/show_binlog_events.inc
 Log_name	Pos	Event_type	Server_id	End_log_pos	Info
diff --git a/mysql-test/t/stat_tables_partition.test b/mysql-test/t/stat_tables_partition.test
index 1316e5cca11..11b74818d82 100644
--- a/mysql-test/t/stat_tables_partition.test
+++ b/mysql-test/t/stat_tables_partition.test
@@ -11,7 +11,33 @@ CREATE TABLE t1 (pk int PRIMARY KEY, a bit(1), INDEX idx(a)
 INSERT INTO t1 VALUES (1,1),(2,0),(3,0),(4,1);
 
 ANALYZE TABLE t1;
+DROP TABLE t1;
 
-SET use_stat_tables = DEFAULT;
+--echo #
+--echo # MDEV-21472: ALTER TABLE ... ANALYZE PARTITION ... with EITS reads and locks all rows
+--echo #
+CREATE TABLE t1 (
+  id int(11) auto_increment primary key,
+  c1 int(11) DEFAULT NULL
+) PARTITION BY RANGE (id) (
+  PARTITION p0 VALUES LESS THAN (4),
+  PARTITION p1 VALUES LESS THAN MAXVALUE
+);
 
-DROP TABLE t1;
+insert into t1(c1) values (1),(1),(1),(1),  (1),(1),(1),(1);
+insert into t1(c1) select c1 from t1;
+insert into t1(c1) select c1 from t1;
+
+select count(*) from t1;
+select count(*) from t1 where id <4;
+flush status;
+set session use_stat_tables='preferably';
+
+--echo # Must NOT show "Engine-independent statistics collected":
+alter table t1 analyze partition p0;
+
+--echo # Should not have Handler_read_rnd_next=34
+show session status like 'Handler_read_rnd%';
+drop table t1;
+
+SET use_stat_tables = DEFAULT;
diff --git a/sql/sql_admin.cc b/sql/sql_admin.cc
index 4afaff58223..beecf3fae64 100644
--- a/sql/sql_admin.cc
+++ b/sql/sql_admin.cc
@@ -727,8 +727,18 @@ static bool mysql_admin_table(THD* thd, TABLE_LIST* tables,
       {
         compl_result_code= result_code= HA_ADMIN_INVALID;
       }
+
+      /*
+        The check for Alter_info::ALTER_ADMIN_PARTITION implements this logic:
+        do not collect EITS STATS for this syntax:
+          ALTER TABLE ... ANALYZE PARTITION p
+        EITS statistics is global (not per-partition). Collecting global stats
+        is much more expensive processing just one partition, so the most
+        appropriate action is to just not collect EITS stats for this command.
+      */
       collect_eis=
         (table->table->s->table_category == TABLE_CATEGORY_USER &&
+        !(lex->alter_info.flags &= Alter_info::ALTER_ADMIN_PARTITION) &&
          (get_use_stat_tables_mode(thd) > NEVER ||
           lex->with_persistent_for_clause));