Crash in purge after instant DROP and emptying the table

--source include/have_innodb.inc

SET @saved_frequency = @@GLOBAL.innodb_purge_rseg_truncate_frequency;

SET GLOBAL innodb_purge_rseg_truncate_frequency=1;

connect (prevent_purge,localhost,root);

START TRANSACTION WITH CONSISTENT SNAPSHOT;

connection default;

CREATE TABLE t1 (f1 INT, f2 INT) ENGINE=InnoDB;

INSERT INTO t1 () VALUES ();

ALTER TABLE t1 DROP f2, ADD COLUMN f2 INT;

ALTER TABLE t1 DROP f1;

DELETE FROM t1;

disconnect prevent_purge;

ALTER TABLE t1 ADD COLUMN extra TINYINT UNSIGNED NOT NULL DEFAULT 42;

ALTER TABLE t1 DROP extra;

--source include/wait_all_purged.inc

DROP TABLE t1;

SET GLOBAL innodb_purge_rseg_truncate_frequency = @saved_frequency;

2018-11-22  8:54:07 1 [ERROR] InnoDB: Trying to access update undo rec field 7 in index `GEN_CLUST_INDEX` of table `test`.`t1` but index has only 4 fields Submit a detailed bug report to https://jira.mariadb.org/. Run also CHECK TABLE `test`.`t1`. n_fields = 2, i = 1

mysqld: /mariadb/10.4/storage/innobase/trx/trx0rec.cc:1661: byte* trx_undo_update_rec_get_update(const byte*, dict_index_t*, ulint, trx_id_t, roll_ptr_t, ulint, mem_heap_t*, upd_t**): Assertion `0' failed.

…

#8  0x000055f3803ad2de in trx_undo_update_rec_get_update (ptr=0x55f382989c2d "\360\377\377\377\377\001l\363U", index=0x7ff434080008, type=12, trx_id=70, roll_ptr=7599824392815061, info_bits=48, heap=0x55f382989b60, upd=0x55f382989090) at /mariadb/10.4/storage/innobase/trx/trx0rec.cc:1661

#9  0x000055f380339699 in row_purge_parse_undo_rec (node=0x55f382989028, undo_rec=0x55f382989bf8 "", updated_extern=0x7ff46e708cae, thr=0x55f382988b80) at /mariadb/10.4/storage/innobase/row/row0purge.cc:1143

diff --git a/storage/innobase/include/dict0mem.h b/storage/innobase/include/dict0mem.h

index 7e6fe455b72..9035cb60e51 100644

--- a/storage/innobase/include/dict0mem.h

+++ b/storage/innobase/include/dict0mem.h

@@ -2131,11 +2131,17 @@ inline void dict_index_t::clear_instant_add()

 	n_core_null_bytes = UT_BITS_IN_BYTES(unsigned(n_nullable));

 }

+#include <my_stacktrace.h>

+

 inline void dict_index_t::clear_instant_alter()

 {

 	DBUG_ASSERT(is_primary());

 	DBUG_ASSERT(n_fields == n_def);

+	extern ulonglong my_thread_stack_size;

+	fprintf(stderr, "clear %u\n", table->n_dropped());

+	my_print_stacktrace(NULL, my_thread_stack_size, 0);

+

 	if (!table->instant) {

 		if (is_instant()) {

 			clear_instant_add();

clear 3

stack_bottom = 0x0 thread_stack 0x49000

/dev/shm/10.4/sql/mysqld(my_print_stacktrace+0x40)[0x56001405179f]

mysys/stacktrace.c:269(my_print_stacktrace)[0x560013b71dc8]

include/dict0mem.h:2145(dict_index_t::clear_instant_alter())[0x560013b60bc5]

handler/handler0alter.cc:5500(innobase_instant_try(Alter_inplace_info const*, ha_innobase_inplace_ctx*, TABLE const*, TABLE const*, trx_t*))[0x560013b7acad]

handler/handler0alter.cc:9888(commit_try_norebuild(Alter_inplace_info*, ha_innobase_inplace_ctx*, TABLE*, TABLE const*, trx_t*, char const*))[0x560013b6e1a5]

handler/handler0alter.cc:10515(ha_innobase::commit_inplace_alter_table(TABLE*, Alter_inplace_info*, bool))[0x56001392502b]

(gdb) frame 8

#8  0x000055f3803ad2de in trx_undo_update_rec_get_update (ptr=0x55f382989c2d "\360\377\377\377\377\001l\363U", index=0x7ff434080008, type=12, trx_id=70, roll_ptr=7599824392815061, info_bits=48, heap=0x55f382989b60, upd=0x55f382989090) at /mariadb/10.4/storage/innobase/trx/trx0rec.cc:1661

(gdb) p/u *ptr@2

$1 = {1, 42}

--source include/have_innodb.inc

SET @saved_frequency = @@GLOBAL.innodb_purge_rseg_truncate_frequency;

SET GLOBAL innodb_purge_rseg_truncate_frequency=1;

connect (prevent_purge,localhost,root);

START TRANSACTION WITH CONSISTENT SNAPSHOT;

connection default;

CREATE TABLE t1 (f1 INT, f2 INT) ENGINE=InnoDB;

INSERT INTO t1 () VALUES ();

ALTER TABLE t1 DROP f2, ADD COLUMN f2 INT;

ALTER TABLE t1 DROP f1;

DELETE FROM t1;

connection prevent_purge;

COMMIT;

START TRANSACTION WITH CONSISTENT SNAPSHOT;

connection default;

ALTER TABLE t1 ADD COLUMN extra TINYINT UNSIGNED NOT NULL DEFAULT 42;

let $wait_all_purged= 1;

--source include/wait_all_purged.inc

ALTER TABLE t1 DROP extra;

disconnect prevent_purge;

let $wait_all_purged= 0;

--source include/wait_all_purged.inc

DROP TABLE t1;

SET GLOBAL innodb_purge_rseg_truncate_frequency = @saved_frequency;

diff --git a/storage/innobase/handler/handler0alter.cc b/storage/innobase/handler/handler0alter.cc

index 8b8ccd2fc11..f6fb498b4a1 100644

--- a/storage/innobase/handler/handler0alter.cc

+++ b/storage/innobase/handler/handler0alter.cc

@@ -5496,6 +5496,11 @@ static bool innobase_instant_try(

 		/* The table is empty. */

 		ut_ad(page_is_root(block->frame));

 		btr_page_empty(block, NULL, index, 0, &mtr);

+		if (index->table->instant) {

+			/* FIXME: Assign a new index->table->id,

+			SYS_TABLES.TABLE_ID, SYS_INDEXES.TABLE_ID

+			to invalidate old undo log records in purge. */

+		}

 		index->clear_instant_alter();

 		err = DB_SUCCESS;

 		goto func_exit;