[MDEV-25560] Creating table with certain generated column crashes server Created: 2021-04-28  Updated: 2021-07-23  Resolved: 2021-07-23

Status: Closed
Project: MariaDB Server
Component/s: Data Definition - Create Table, Server, Virtual Columns
Affects Version/s: 10.4.17, 10.3, 10.4, 10.5
Fix Version/s: 10.3.31, 10.4.21, 10.5.12, 10.6.4

Type: Bug Priority: Major
Reporter: Christopher Granahan Assignee: Nikita Malyavin
Resolution: Fixed Votes: 0
Labels: crash
Environment:

Windows 10, InnoDB


 Description   

Consider the following table definition:

CREATE TABLE crash_test_1 (
DATA_VALUE CHAR(10) NULL,
HAS_DATA BIT NOT NULL,
TEST_COLUMN CHAR(10) AS (CASE WHEN HAS_DATA = 1 THEN DATA_VALUE ELSE NULL END) STORED
);

On creating or selecting from this table, I receive the following warning:

Function or expression 'case when "HAS_DATA" = 1 then "DATA VALUE" else NULL end' cannot be used in the GENERATED ALWAYS AS clause of `TEST_COLUMN`
Warning: Expression depends on the @@sql_mode value PAD_CHAR_TO_FULL_LENGTH

So, as per the documentation, I tried using RPAD:

CREATE TABLE crash_test_2 (
DATA_VALUE CHAR(10) NULL,
HAS_DATA BIT NOT NULL,
TEST_COLUMN CHAR(10) AS (RPAD(CASE WHEN HAS_DATA = 1 THEN DATA_VALUE ELSE NULL END, 10)) STORED
);

Here is the real problem. Attempting to create crash_test_2 causes the server to crash. Some info from the error log:

[ERROR] mysqld got exception 0xc0000005 ;

mysqld.exe!Item_func_rpad::value_depends_on_sql_mode()[item_strfunc.cc:3262]
mysqld.exe!Field::check_vcol_sql_mode_dependency()[field.cc:1411]
mysqld.exe!parse_vcol_defs()[table.cc:1185]
mysqld.exe!open_table_from_share()[table.cc:3846]
mysqld.exe!ha_create_table()[handler.cc:5237]
mysqld.exe!create_table_impl()[sql_table.cc:5094]
mysqld.exe!mysql_create_table_no_lock()[sql_table.cc:5182]
mysqld.exe!mysql_create_table()[sql_table.cc:5274]
mysqld.exe!Sql_cmd_create_table_like::execute()[sql_table.cc:11503]
mysqld.exe!mysql_execute_command()[sql_parse.cc:6153]
mysqld.exe!mysql_parse()[sql_parse.cc:7942]
mysqld.exe!dispatch_command()[sql_parse.cc:1842]
mysqld.exe!do_command()[sql_parse.cc:1357]
mysqld.exe!threadpool_process_request()[threadpool_common.cc:374]
mysqld.exe!tp_callback()[threadpool_common.cc:192]
ntdll.dll!TpAllocPool()
ntdll.dll!TpReleaseCleanupGroupMembers()
KERNEL32.DLL!BaseThreadInitThunk()
ntdll.dll!RtlUserThreadStart()

Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=on,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=on,condition_pushdown_for_derived=on,split_materialized=on,condition_pushdown_for_subquery=on,rowid_filter=on,condition_pushdown_from_having=on

 Comments   
Comment by Alice Sherepa [ 2021-04-29 ]

Thank you for the report! I repeated as described on 10.3-10.5:

10.3 23e090626a9138f44905a5

 
Version: '10.3.29-MariaDB-debug-log'  
/10.3/sql/item_strfunc.cc:3235: virtual Sql_mode_dependency Item_func_rpad::value_depends_on_sql_mode() const: Assertion `arg_count == 3' failed.
 
210429  7:20:17 [ERROR] mysqld got signal 6 ;
 
 
 
Server version: 10.3.29-MariaDB-debug-log
 
 
 
/lib/x86_64-linux-gnu/libc.so.6(+0x30102)[0x7f6c03c5e102]
 
sql/item_strfunc.cc:3236(Item_func_rpad::value_depends_on_sql_mode() const)[0x55f25ae24c1e]
 
sql/field.cc:1401(Field::check_vcol_sql_mode_dependency(THD*, vcol_init_mode) const)[0x55f25ab72cac]
 
sql/table.cc:1101(parse_vcol_defs(THD*, st_mem_root*, TABLE*, bool*, vcol_init_mode))[0x55f25a77fa51]
 
sql/table.cc:3430(open_table_from_share(THD*, TABLE_SHARE*, st_mysql_const_lex_string const*, unsigned int, unsigned int, unsigned int, TABLE*, bool, List<String>*))[0x55f25a795579]
 
sql/handler.cc:5200(ha_create_table(THD*, char const*, char const*, char const*, HA_CREATE_INFO*, st_mysql_const_unsigned_lex_string*))[0x55f25ac573d5]
 
sql/unireg.cc:515(rea_create_table(THD*, st_mysql_const_unsigned_lex_string*, char const*, char const*, char const*, HA_CREATE_INFO*, handler*, bool))[0x55f25a7e6328]
 
sql/sql_table.cc:5098(create_table_impl(THD*, st_mysql_const_lex_string const*, st_mysql_const_lex_string const*, st_mysql_const_lex_string const*, st_mysql_const_lex_string const*, char const*, DDL_options_st, HA_CREATE_INFO*, Alter_info*, int, bool*, st_key**, unsigned int*, st_mysql_const_unsigned_lex_string*))[0x55f25a6da93d]
 
sql/sql_table.cc:5217(mysql_create_table_no_lock(THD*, st_mysql_const_lex_string const*, st_mysql_const_lex_string const*, Table_specification_st*, Alter_info*, bool*, int, TABLE_LIST*))[0x55f25a6db6f0]
 
sql/sql_table.cc:5312(mysql_create_table(THD*, TABLE_LIST*, Table_specification_st*, Alter_info*))[0x55f25a6dc228]
 
sql/sql_table.cc:11369(Sql_cmd_create_table_like::execute(THD*))[0x55f25a709abe]
 
sql/sql_parse.cc:6078(mysql_execute_command(THD*))[0x55f25a495fdf]
 
sql/sql_parse.cc:7873(mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool))[0x55f25a4a2659]
 
sql/sql_parse.cc:1855(dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool))[0x55f25a478d17]
 
sql/sql_parse.cc:1398(do_command(THD*))[0x55f25a475452]
 
sql/sql_connect.cc:1403(do_handle_one_connection(CONNECT*))[0x55f25a8696a7]
 
sql/sql_connect.cc:1309(handle_one_connection)[0x55f25a868f5f]
 
perfschema/pfs.cc:1871(pfs_spawn_thread)[0x55f25bfe6275]
 
nptl/pthread_create.c:487(start_thread)[0x7f6c03df6fa3]
 
x86_64/clone.S:97(clone)[0x7f6c03d274cf]
 
 
 
Query (0x62b000000410): CREATE TABLE crash_test_2 (
 
DATA_VALUE CHAR(10) NULL,
 
HAS_DATA BIT NOT NULL,
 
TEST_COLUMN CHAR(10) AS (RPAD(CASE WHEN HAS_DATA = 1 THEN DATA_VALUE ELSE NULL END, 10)) stored 
)


CREATE TABLE t1 (i int, b int AS (RPAD(123,1)) stored);

Comment by Nikita Malyavin [ 2021-06-26 ]

Hello novog and thanks for a submission!

I will soon submit the fix for a review. Until then, you can work around the problem by passing ' ' (a space) as a third argument – the bug was that we did not handle a possibility of two argument input in one place (sql mode dependancies computation)

Comment by Nikita Malyavin [ 2021-06-28 ]

Patch for review is: b2965aa554

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