[MDEV-12255] innodb_prefix_index_cluster_optimization hits debug build assert on UTF-8 columns Created: 2017-03-14  Updated: 2021-04-27  Resolved: 2018-03-20

Status: Closed
Project: MariaDB Server
Component/s: Storage Engine - InnoDB
Affects Version/s: 10.1, 10.2
Fix Version/s: 10.1.32, 10.2.14

Type: Bug Priority: Major
Reporter: Laurynas Biveinis Assignee: Thirunarayanan Balathandayuthapani
Resolution: Fixed Votes: 1
Labels: None

Issue Links:
Problem/Incident
causes MDEV-23600 SIGFPE in row_search_with_covering_pr... Closed
is caused by MDEV-6929 Port Facebook Prefix Index Queries Op... Closed
Relates
relates to MDEV-12486 Incorrect results with prefix_index_c... Closed
relates to MDEV-25440 Assertion `cmp_rec_rec(rec, old_rec, ... Closed
Sprint: 10.1.32

 Description    

./mtr --do-test=ctype --mysqld=--innodb_prefix_index_cluster_optimization=ON
 
...
 
2017-03-14 14:48:08 700001c51000  InnoDB: Assertion failure in thread 123145332002816 in file row0sel.cc line 2717
 
InnoDB: Failing assertion: len * templ->mbmaxlen >= templ->mysql_col_len || (field_no == templ->icp_rec_field_no && field->prefix_len > 0)
 
...
 
Failing test(s): main.ctype_utf8 main.ctype_utf8mb4 main.ctype_utf8mb4_innodb

This is a parallel bug to https://github.com/facebook/mysql-5.6/issues/568, but appears to be less serious, as Facebook patch silently returns wrong query results too, whereas MariaDB only crashes the debug build. I don't know if these testcases return correct results in the release build.

 Comments   
Comment by Elena Stepanova [ 2017-04-17 ]

10.1 3bb32e8682f849413ce994277e9029ba5732baae

 
2017-04-17 17:06:00 7f5c22fdbb00  InnoDB: Assertion failure in thread 140033700772608 in file row0sel.cc line 2709
 
InnoDB: Failing assertion: len * templ->mbmaxlen >= templ->mysql_col_len || (field_no == templ->icp_rec_field_no && field->prefix_len > 0)
 
InnoDB: We intentionally generate a memory trap.
 
 
 
#5  0x00007f5c1f8d4448 in __GI_abort () at abort.c:89
 
#6  0x00007f5c19030393 in row_sel_field_store_in_mysql_format_func (dest=0x7f5c0a0a1e89 "a", '\217' <repeats 29 times>, "\245\377", '\245' <repeats 31 times>, "\330\036\n\n\\\177", templ=0x7f5c0a28a378, index=0x7f5c0a1269f8, field_no=0, data=0x7f5c16b2407f "a", len=1) at /data/src/10.1/storage/innobase/row/row0sel.cc:2707
 
#7  0x00007f5c190309ce in row_sel_store_mysql_field_func (mysql_rec=0x7f5c0a0a1e88 "\377a", '\217' <repeats 29 times>, "\245\377", '\245' <repeats 31 times>, "\330\036\n\n\\\177", prebuilt=0x7f5c0a084678, rec=0x7f5c16b2407f "a", index=0x7f5c0a1269f8, offsets=0x7f5c22fd85c0, field_no=0, templ=0x7f5c0a28a378) at /data/src/10.1/storage/innobase/row/row0sel.cc:2882
 
#8  0x00007f5c19030b7b in row_sel_store_mysql_rec (mysql_rec=0x7f5c0a0a1e88 "\377a", '\217' <repeats 29 times>, "\245\377", '\245' <repeats 31 times>, "\330\036\n\n\\\177", prebuilt=0x7f5c0a084678, rec=0x7f5c16b2407f "a", rec_clust=0, index=0x7f5c0a1269f8, offsets=0x7f5c22fd85c0) at /data/src/10.1/storage/innobase/row/row0sel.cc:2946
 
#9  0x00007f5c19034b61 in row_search_for_mysql (buf=0x7f5c0a0a1e88 "\377a", '\217' <repeats 29 times>, "\245\377", '\245' <repeats 31 times>, "\330\036\n\n\\\177", mode=2, prebuilt=0x7f5c0a084678, match_mode=1, direction=0) at /data/src/10.1/storage/innobase/row/row0sel.cc:5012
 
#10 0x00007f5c18efe7c0 in ha_innodb::index_read (this=0x7f5c0a0b3888, buf=0x7f5c0a0a1e88 "\377a", '\217' <repeats 29 times>, "\245\377", '\245' <repeats 31 times>, "\330\036\n\n\\\177", key_ptr=0x7f5c0a0fc310 "", key_len=4, find_flag=HA_READ_KEY_EXACT) at /data/src/10.1/storage/innobase/handler/ha_innodb.cc:9310
 
#11 0x00007f5c18f14b44 in handler::index_read_map (this=0x7f5c0a0b3888, buf=0x7f5c0a0a1e88 "\377a", '\217' <repeats 29 times>, "\245\377", '\245' <repeats 31 times>, "\330\036\n\n\\\177", key=0x7f5c0a0fc310 "", keypart_map=1, find_flag=HA_READ_KEY_EXACT) at /data/src/10.1/sql/handler.h:3052
 
#12 0x00007f5c2231b2b0 in handler::index_read_idx_map (this=0x7f5c0a0b3888, buf=0x7f5c0a0a1e88 "\377a", '\217' <repeats 29 times>, "\245\377", '\245' <repeats 31 times>, "\330\036\n\n\\\177", index=0, key=0x7f5c0a0fc310 "", keypart_map=1, find_flag=HA_READ_KEY_EXACT) at /data/src/10.1/sql/handler.cc:5443
 
#13 0x00007f5c22314dfb in handler::ha_index_read_idx_map (this=0x7f5c0a0b3888, buf=0x7f5c0a0a1e88 "\377a", '\217' <repeats 29 times>, "\245\377", '\245' <repeats 31 times>, "\330\036\n\n\\\177", index=0, key=0x7f5c0a0fc310 "", keypart_map=1, find_flag=HA_READ_KEY_EXACT) at /data/src/10.1/sql/handler.cc:2646
 
#14 0x00007f5c22140faa in join_read_const (tab=0x7f5c0a0fb2b8) at /data/src/10.1/sql/sql_select.cc:18893
 
#15 0x00007f5c22140aa9 in join_read_const_table (thd=0x7f5c163a6070, tab=0x7f5c0a0fb2b8, pos=0x7f5c0a0fb808) at /data/src/10.1/sql/sql_select.cc:18768
 
#16 0x00007f5c2211c515 in make_join_statistics (join=0x7f5c0a0fac68, tables_list=..., keyuse_array=0x7f5c0a0fafa0) at /data/src/10.1/sql/sql_select.cc:3936
 
#17 0x00007f5c2211345b in JOIN::optimize_inner (this=0x7f5c0a0fac68) at /data/src/10.1/sql/sql_select.cc:1366
 
#18 0x00007f5c22112346 in JOIN::optimize (this=0x7f5c0a0fac68) at /data/src/10.1/sql/sql_select.cc:1045
 
#19 0x00007f5c2211a9aa in mysql_select (thd=0x7f5c163a6070, rref_pointer_array=0x7f5c163aa430, tables=0x7f5c0a0fa298, wild_num=0, fields=..., conds=0x7f5c0a0faa28, og_num=0, order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2147748608, result=0x7f5c0a0fac48, unit=0x7f5c163a9ab8, select_lex=0x7f5c163aa1b8) at /data/src/10.1/sql/sql_select.cc:3431
 
#20 0x00007f5c22110496 in handle_select (thd=0x7f5c163a6070, lex=0x7f5c163a99f0, result=0x7f5c0a0fac48, setup_tables_done_option=0) at /data/src/10.1/sql/sql_select.cc:384
 
#21 0x00007f5c220e03fb in execute_sqlcom_select (thd=0x7f5c163a6070, all_tables=0x7f5c0a0fa298) at /data/src/10.1/sql/sql_parse.cc:5920
 
#22 0x00007f5c220d68f7 in mysql_execute_command (thd=0x7f5c163a6070) at /data/src/10.1/sql/sql_parse.cc:2979
 
#23 0x00007f5c220e3b19 in mysql_parse (thd=0x7f5c163a6070, rawbuf=0x7f5c0a0fa088 "select c as c_a from t1 where c='a'", length=35, parser_state=0x7f5c22fda5e0) at /data/src/10.1/sql/sql_parse.cc:7343
 
#24 0x00007f5c220d2b06 in dispatch_command (command=COM_QUERY, thd=0x7f5c163a6070, packet=0x7f5c1829b071 "select c as c_a from t1 where c='a'", packet_length=35) at /data/src/10.1/sql/sql_parse.cc:1490
 
#25 0x00007f5c220d1865 in do_command (thd=0x7f5c163a6070) at /data/src/10.1/sql/sql_parse.cc:1109
 
#26 0x00007f5c222086aa in do_handle_one_connection (thd_arg=0x7f5c163a6070) at /data/src/10.1/sql/sql_connect.cc:1349
 
#27 0x00007f5c2220840e in handle_one_connection (arg=0x7f5c163a6070) at /data/src/10.1/sql/sql_connect.cc:1261
 
#28 0x00007f5c225be10c in pfs_spawn_thread (arg=0x7f5c182b8970) at /data/src/10.1/storage/perfschema/pfs.cc:1860
 
#29 0x00007f5c217ce064 in start_thread (arg=0x7f5c22fdbb00) at pthread_create.c:309
 
#30 0x00007f5c1f98662d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111

On a release build, the tests return wrong results, e.g.

main.ctype_utf8 'innodb_plugin'          [ fail ]
 
        Test ended at 2017-04-17 17:02:57
 
 
 
CURRENT_TEST: main.ctype_utf8
 
--- /data/bld/10.1-rel/mysql-test/r/ctype_utf8.result	2017-03-11 16:20:47.000000000 +0200
 
+++ /data/bld/10.1-rel/mysql-test/r/ctype_utf8.reject	2017-04-17 17:02:57.068614168 +0300
 
@@ -448,7 +448,6 @@
 
 aaaaaaaaaa
 
 select c cb20 from t1 where c=repeat('b',20);
 
 cb20
 
-bbbbbbbbbbbbbbbbbbbb
 
 drop table t1;
 
 create table t1 (c char(3) character set utf8, unique (c(2)));
 
 insert into t1 values ('1'),('2'),('3'),('4'),('x'),('y'),('z');
 
@@ -774,7 +773,6 @@
 
 INSERT INTO t1 VALUES ('str2');
 
 select * from t1 where str='str';
 
 str
 
-str
 
 drop table t1;
 
 create table t1 (
 
 str varchar(255) character set utf8 not null,
 
@@ -804,7 +802,6 @@
 
 INSERT INTO t1 VALUES ('str2');
 
 select * from t1 where str='str';
 
 str
 
-str
 
 drop table t1;
 
 CREATE TABLE t1 (a varchar(32) BINARY) CHARACTER SET utf8;
 
 INSERT INTO t1 VALUES ('test');
 
@@ -887,11 +884,9 @@
 
 insert into t1 values(1,'foo'),(2,'foobar');
 
 select * from t1 where b like 'foob%';
 
 a	b
 
-2	foobar
 
 alter table t1 engine=innodb;
 
 select * from t1 where b like 'foob%';
 
 a	b
 
-2	foobar
 
 drop table t1;
 
 create table t1 (
 
 a enum('петя','вася','анюта') character set utf8 not null default 'анюта',
 
@@ -2067,7 +2062,6 @@
 
 WHERE t1.colA < 3;
 
 colA	colB	colA	colB
 
 1	foo	1	foo
 
-2	foo bar	2	foo bar
 
 DROP TABLE t1, t2;
 
 SELECT 'н1234567890' UNION SELECT _binary '1';
 
 н1234567890
 
 
 
mysqltest: Result length mismatch

We also have another bug report about wrong results with this option, MDEV-12486.

Comment by Thirunarayanan Balathandayuthapani [ 2018-03-16 ]

Assert in row_sel_field_store_in_mysql_format_func():

                ut_ad(len * templ->mbmaxlen >= templ->mysql_col_len
 
                      || (field_no == templ->icp_rec_field_no
 
                          && field->prefix_len > 0));

looks very strict and wrong for --innodb_prefix_index_cluster_optimization case.

There is no index condition pushdown. so let's ignore the second condition.

The problematic assert is (len * templ->mbmaxlen >= templ->mysql_col_len).

--source include/have_innodb.inc
 
set global innodb_prefix_index_cluster_optimization = 1;
 
let collation=utf8_unicode_ci;
 
--source include/have_collation.inc
 
 
 
set names utf8;
 
--source include/ctype_regex.inc
 
--source include/ctype_regex_utf8.inc
 
 
 
create table t1 (
 
c char(10) character set utf8,
 
unique key a (c(1)))engine=innodb;
 
insert into t1 values ('a');
 
select c as c_a from t1 where c='a';

For the above test case, InnoDB fetches record from secondary index which is of size "1" and field->prefix_len is 3.
So, it satisfies the condition to avoid lookup for clustered index.

Using secondary index record, row_sel_store_mysql_rec() to convert the innodb record to mysql record.
length will be 1 as expected. templ->mbmaxlen will be 3, but templ->mysql_col_len will be 30. Above condition fails.

 --source include/have_innodb.inc
 
set global innodb_prefix_index_cluster_optimization = 1;
 
create table t1 (
 
c char(10) character set utf8,
 
c1 char(10) character set utf8,
 
index (c(4), c1(4))
 
) engine=innodb;
 
insert into t1 values ('a', 't');
 
select c, c1 as c_a from t1 where c='a';
 
drop table t1;

Above test case also fails with assert.

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