MDEV-15418 innodb_force_recovery=5 displays bogus warnings

With MDEV-15132 in MariaDB 10.3.5, InnoDB no longer writes the
transaction identifier to the TRX_SYS page. The information is
only written to undo log headers and sometimes rollback segment
headers. Because the setting innodb_force_recovery=5 will skip
reading any of those pages, the maximum transaction identifier
will no longer be determined.

innobase_map_isolation_level(): Always report READ UNCOMMITTED
if innodb_force_recovery has been set to 5 or more, or
innodb_read_only is set. This will avoid errors reported by
lock_check_trx_id_sanity() and ReadView::check_trx_id_sanity().

lock_clust_rec_cons_read_sees(): Do not check for
innodb_read_only, now that innobase_map_isolation_level() will
guarantee that no read view will be created or used.

row_search_mvcc(): Do not check for innodb_force_recovery<5,
now that innobase_map_isolation_level() will guarantee that
no read view will be created or used.

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

@@ -3,7 +3,7 @@ CREATE TABLE t(a INT PRIMARY KEY) ENGINE=InnoDB;
 INSERT INTO t VALUES(1);
 BEGIN;
 INSERT INTO t VALUES(2);
-DELETE FROM t WHERE a=2;
+UPDATE t SET a=20 WHERE a=2;
 connect con2, localhost, root;
 # Normal MariaDB shutdown would roll back the above transaction.
 # We want the transaction to remain open, so we will kill the server
@@ -15,7 +15,7 @@ SET DEBUG_SYNC='after_trx_committed_in_memory SIGNAL committed WAIT_FOR ever';
 COMMIT;
 connection default;
 SET DEBUG_SYNC='now WAIT_FOR committed';
-# Ensure that the above incomplete transactions become durable.
+# Ensure that the above transactions become durable.
 SET GLOBAL innodb_flush_log_at_trx_commit=1;
 BEGIN;
 INSERT INTO t VALUES(-10000);
@@ -29,17 +29,39 @@ SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
 SELECT * FROM t;
 a
 1
+20
 UPDATE t SET a=3 WHERE a=1;
 # Starting with MariaDB 10.2, innodb_read_only implies READ UNCOMMITTED.
 # In earlier versions, this would return the last committed version
-# (empty table)!
+# (only a=3; no record for a=20)!
 SELECT * FROM t;
 a
 3
+20
 SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
 SELECT * FROM t;
 a
 3
+20
+#
+# MDEV-15418 innodb_force_recovery=5 displays bogus warnings
+#            about too new transaction identifier
+#
+# With the fix, innodb_force_recovery=5 implies READ UNCOMMITTED.
+SELECT * FROM t;
+a
+3
+20
+SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
+SELECT * FROM t;
+a
+3
+20
+SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
+SELECT * FROM t;
+a
+3
+20
 SELECT * FROM t;
 a
 3

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

@@ -4,14 +4,21 @@
 # need to restart server
 --source include/not_embedded.inc
 
+--disable_query_log
+# Ignore messages from the innodb_force_recovery=5 startup.
+call mtr.add_suppression("\\[ERROR\\] InnoDB: Failed to find tablespace for table `test`\\.`t` in the cache");
+call mtr.add_suppression("\\[Warning\\] InnoDB: Allocated tablespace ID.* for test/t, old maximum was 0");
+FLUSH TABLES;
+--enable_query_log
+
 --connect(con1, localhost, root)
 CREATE TABLE t(a INT PRIMARY KEY) ENGINE=InnoDB;
 INSERT INTO t VALUES(1);
 BEGIN;
 # Generate insert_undo log.
 INSERT INTO t VALUES(2);
 # Generate update_undo log.
-DELETE FROM t WHERE a=2;
+UPDATE t SET a=20 WHERE a=2;
 --connect(con2, localhost, root)
 --echo # Normal MariaDB shutdown would roll back the above transaction.
 --echo # We want the transaction to remain open, so we will kill the server
@@ -34,7 +41,7 @@ send COMMIT;
 
 connection default;
 SET DEBUG_SYNC='now WAIT_FOR committed';
---echo # Ensure that the above incomplete transactions become durable.
+--echo # Ensure that the above transactions become durable.
 SET GLOBAL innodb_flush_log_at_trx_commit=1;
 BEGIN;
 INSERT INTO t VALUES(-10000);
@@ -54,10 +61,22 @@ UPDATE t SET a=3 WHERE a=1;
 --source include/restart_mysqld.inc
 --echo # Starting with MariaDB 10.2, innodb_read_only implies READ UNCOMMITTED.
 --echo # In earlier versions, this would return the last committed version
---echo # (empty table)!
+--echo # (only a=3; no record for a=20)!
 SELECT * FROM t;
 SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
 SELECT * FROM t;
+--let $restart_parameters= --innodb-force-recovery=5
+--source include/restart_mysqld.inc
+--echo #
+--echo # MDEV-15418 innodb_force_recovery=5 displays bogus warnings
+--echo #            about too new transaction identifier
+--echo #
+--echo # With the fix, innodb_force_recovery=5 implies READ UNCOMMITTED.
+SELECT * FROM t;
+SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
+SELECT * FROM t;
+SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
+SELECT * FROM t;
 --let $restart_parameters=
 --source include/restart_mysqld.inc
 SELECT * FROM t;

storage/innobase/handler/ha_innodb.cc

@@ -15785,6 +15785,10 @@ innobase_map_isolation_level(
 /*=========================*/
 	enum_tx_isolation	iso)	/*!< in: MySQL isolation level code */
 {
+	if (UNIV_UNLIKELY(srv_force_recovery >= SRV_FORCE_NO_UNDO_LOG_SCAN)
+	    || UNIV_UNLIKELY(srv_read_only_mode)) {
+		return TRX_ISO_READ_UNCOMMITTED;
+	}
 	switch (iso) {
 	case ISO_REPEATABLE_READ:	return(TRX_ISO_REPEATABLE_READ);
 	case ISO_READ_COMMITTED:	return(TRX_ISO_READ_COMMITTED);

storage/innobase/lock/lock0lock.cc

@@ -414,9 +414,7 @@ lock_clust_rec_cons_read_sees(
 	transactions from different connections cannot simultaneously
 	operate on same temp-table and so read of temp-table is
 	always consistent read. */
-	if (srv_read_only_mode || dict_table_is_temporary(index->table)) {
-		ut_ad(!view->is_open()
-		      || dict_table_is_temporary(index->table));
+	if (index->table->is_temporary()) {
 		return(true);
 	}
 

storage/innobase/row/row0sel.cc

@@ -5030,10 +5030,10 @@ row_search_mvcc(
 			high force recovery level set, we try to avoid crashes
 			by skipping this lookup */
 
-			if (srv_force_recovery < 5
-			    && !lock_clust_rec_cons_read_sees(
+			if (!lock_clust_rec_cons_read_sees(
 				    rec, index, offsets, &trx->read_view)) {
-
+				ut_ad(srv_force_recovery
+				      < SRV_FORCE_NO_UNDO_LOG_SCAN);
 				rec_t*	old_vers;
 				/* The following call returns 'offsets'
 				associated with 'old_vers' */