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  1. MariaDB Server
  2. MDEV-6689

valgrind errors in view.test in 10.1

        Details

        • Type: Bug
        • Status: Closed
        • Priority: Major
        • Resolution: Fixed
        • Affects Version/s: 10.1.1
        • Fix Version/s: 10.1.1
        • Component/s: None
        • Labels:
          None

          Description

          Filing based on discussion with Michael Widenius.

          This is a different problem than MDEV-6575.

          The errors look like this:

          ==2976== Conditional jump or move depends on uninitialised value(s)
==2976==    at 0x5381F0: st_join_table::save_explain_data(Explain_table_access*, unsigned long long, bool, st_join_table*) (sql_show.h:205)
==2976==    by 0x539E10: JOIN::save_explain_data_intern(Explain_query*, bool, bool, bool, char const*) (sql_select.cc:23789)
==2976==    by 0x540745: JOIN::optimize() (sql_select.cc:1046)
==2976==    by 0x540882: mysql_select(THD*, Item***, TABLE_LIST*, unsigned int, List<Item>&, Item*, unsigned int, st_order*, st_order*, Item*, st_order*, unsigned long long, select_result*, st_select_lex_unit*, st_select_lex*) (sql_select.cc:3306)
==2976==    by 0x543CC3: handle_select(THD*, LEX*, select_result*, unsigned long) (sql_select.cc:372)
==2976==    by 0x4EB8C4: execute_sqlcom_select(THD*, TABLE_LIST*) (sql_parse.cc:5729)
==2976==    by 0x4F248F: mysql_execute_command(THD*) (sql_parse.cc:2809)
==2976==    by 0x4FA71C: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:7011)
==2976==    by 0x4FD811: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1469)
==2976==    by 0x4FDDA1: do_command(THD*) (sql_parse.cc:1092)
==2976==    by 0x5B2351: do_handle_one_connection(THD*) (sql_connect.cc:1394)
==2976==    by 0x5B2505: handle_one_connection (sql_connect.cc:1305)
==2976==    by 0x827102: pfs_spawn_thread (pfs.cc:1860)
==2976==    by 0x60E0E99: start_thread (pthread_create.c:308)
==2976==    by 0x69E63FC: clone (clone.S:112)

          minimal testcase:

          create table t1 (a int);
insert into t1 values (1), (2), (3), (4);
show columns from t1;
drop table t1;

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                psergey Sergei Petrunia added a comment -

                If I take the testcase and replace

                insert into t1 values (1), (2), (3), (4);

                with its more verbose form

                select * from information_schema.columns where table_schema='test' and table_name='t1';

                then the error goes away. Maybe, SHOW COLUMNS takes some shortcuts and doesn't set the value?

                I've rang SHOW COLUMNS under gdb and attempted to catch writes to the data that save_explain_data() does invalid read from. No success...

                Show
                psergey Sergei Petrunia added a comment - If I take the testcase and replace insert into t1 values (1), (2), (3), (4); with its more verbose form select * from information_schema.columns where table_schema='test' and table_name='t1'; then the error goes away. Maybe, SHOW COLUMNS takes some shortcuts and doesn't set the value? I've rang SHOW COLUMNS under gdb and attempted to catch writes to the data that save_explain_data() does invalid read from. No success...
                Hide
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                psergey Sergei Petrunia added a comment -

                static bool optimize_for_get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond)

                there is this code:

                  /* 
    this branch processes SHOW FIELDS, SHOW INDEXES commands.
    see sql_parse.cc, prepare_schema_table() function where
    this values are initialized
  */
  if (lsel && lsel->table_list.first)
  {
    /* These do not need to have a query plan */
    goto end;
  }

                lookup_field_vals is never set.

                Show
                psergey Sergei Petrunia added a comment - static bool optimize_for_get_all_tables(THD *thd, TABLE_LIST *tables, COND *cond) there is this code: /* this branch processes SHOW FIELDS, SHOW INDEXES commands. see sql_parse.cc, prepare_schema_table() function where this values are initialized */ if (lsel && lsel->table_list.first) { /* These do not need to have a query plan */ goto end; } lookup_field_vals is never set.
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                psergey Sergei Petrunia added a comment -

                Maybe, we should not attempt to save explain data structures for SHOW FIELDS and SHOW INDEXES commands.

                Show
                psergey Sergei Petrunia added a comment - Maybe, we should not attempt to save explain data structures for SHOW FIELDS and SHOW INDEXES commands.

                  People

                  • Assignee:
                    psergey Sergei Petrunia
                    Reporter:
                    psergey Sergei Petrunia
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                    Dates

                    • Created:
                      Updated:
                      Resolved: