MDEV-29566 Failed to read from the .par file upon concurrent DDL/SELECT with partition pruning

ha_innobase::delete_table(): If locking the InnoDB persistent statistics
tables mysql.innodb_table_stats or mysql.innodb_index_stats fails for
a table partition, proceed to drop the partition. On DROP TABLE of a
partitioned table, each partition is being dropped in a separate
InnoDB DDL transaction. The only practical way to create an illusion of
atomicity is to avoid failures.

mysql-test/suite/innodb/r/innodb_stats_drop_locked.result

@@ -2,6 +2,8 @@ CREATE DATABASE unlocked;
 CREATE TABLE unlocked.t1(a INT PRIMARY KEY) ENGINE=INNODB STATS_PERSISTENT=0;
 CREATE DATABASE locked;
 CREATE TABLE locked.t1(a INT PRIMARY KEY) ENGINE=INNODB STATS_PERSISTENT=1;
+CREATE TABLE locked.t1p(pk INT PRIMARY KEY) ENGINE=InnoDB STATS_PERSISTENT=1
+PARTITION BY HASH (pk) PARTITIONS 4;
 CREATE TABLE innodb_stats_drop_locked (c INT, KEY c_key (c))
 ENGINE=INNODB STATS_PERSISTENT=1;
 ANALYZE TABLE innodb_stats_drop_locked;
@@ -38,12 +40,25 @@ innodb_stats_drop_locked	CREATE TABLE `innodb_stats_drop_locked` (
 DROP TABLE innodb_stats_drop_locked;
 ERROR HY000: Lock wait timeout exceeded; try restarting transaction
 DROP DATABASE unlocked;
+DROP TABLE locked.t1p;
+SELECT * FROM locked.t1p;
+ERROR 42S02: Table 'locked.t1p' doesn't exist
 DROP DATABASE locked;
 ERROR HY000: Lock wait timeout exceeded; try restarting transaction
 disconnect con1;
 connection default;
 COMMIT;
+SELECT COUNT(*) FROM mysql.innodb_table_stats WHERE database_name='locked';
+COUNT(*)
+5
+SELECT COUNT(*) FROM mysql.innodb_index_stats WHERE database_name='locked';
+COUNT(*)
+15
 DROP DATABASE locked;
+SELECT table_name FROM mysql.innodb_table_stats WHERE database_name='locked';
+table_name
+SELECT table_name FROM mysql.innodb_index_stats WHERE database_name='locked';
+table_name
 SELECT table_name FROM mysql.innodb_table_stats
 WHERE table_name='innodb_stats_drop_locked';
 table_name

mysql-test/suite/innodb/t/innodb_stats_drop_locked.test

@@ -4,12 +4,16 @@
 #
 
 -- source include/have_innodb.inc
+-- source include/have_partition.inc
 
 CREATE DATABASE unlocked;
 CREATE TABLE unlocked.t1(a INT PRIMARY KEY) ENGINE=INNODB STATS_PERSISTENT=0;
 CREATE DATABASE locked;
 CREATE TABLE locked.t1(a INT PRIMARY KEY) ENGINE=INNODB STATS_PERSISTENT=1;
 
+CREATE TABLE locked.t1p(pk INT PRIMARY KEY) ENGINE=InnoDB STATS_PERSISTENT=1
+PARTITION BY HASH (pk) PARTITIONS 4;
+
 CREATE TABLE innodb_stats_drop_locked (c INT, KEY c_key (c))
 ENGINE=INNODB STATS_PERSISTENT=1;
 ANALYZE TABLE innodb_stats_drop_locked;
@@ -35,14 +39,26 @@ SHOW CREATE TABLE innodb_stats_drop_locked;
 DROP TABLE innodb_stats_drop_locked;
 
 DROP DATABASE unlocked;
+
+# Partitions will always be dropped despite locking conflicts.
+DROP TABLE locked.t1p;
+--error ER_NO_SUCH_TABLE
+SELECT * FROM locked.t1p;
+
 --error ER_LOCK_WAIT_TIMEOUT
 DROP DATABASE locked;
 -- disconnect con1
 -- connection default
 COMMIT;
 
+SELECT COUNT(*) FROM mysql.innodb_table_stats WHERE database_name='locked';
+SELECT COUNT(*) FROM mysql.innodb_index_stats WHERE database_name='locked';
+
 DROP DATABASE locked;
 
+SELECT table_name FROM mysql.innodb_table_stats WHERE database_name='locked';
+SELECT table_name FROM mysql.innodb_index_stats WHERE database_name='locked';
+
 # the stats should be there
 
 SELECT table_name FROM mysql.innodb_table_stats

storage/innobase/handler/ha_innodb.cc

@@ -13613,7 +13613,8 @@ int ha_innobase::delete_table(const char *name)
       dict_sys.unfreeze();
     }
 
-    const bool skip_wait{table->name.is_temporary()};
+    const bool skip_wait{table->name.is_temporary() ||
+                         dict_table_is_partition(table)};
 
     if (table_stats && index_stats &&
         !strcmp(table_stats->name.m_name, TABLE_STATS_NAME) &&