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  1. MariaDB Server
  2. MDEV-17784

Analyze table returns warnings due to rounding error or overflow while collection of EITS

Details

    • Bug
    • Status: Stalled (View Workflow)
    • Minor
    • Resolution: Unresolved
    • 10.0(EOL), 10.1(EOL), 10.2(EOL), 10.3(EOL), 10.4(EOL)
    • 10.4(EOL)
    • Optimizer
    • None

    Description

      --source include/have_innodb.inc
      		 
       
      		 
      set @@optimizer_use_condition_selectivity=4;
      		 
      set @@use_stat_tables=PREFERABLY;
      		 
       
      		 
      create table t1 (a int)engine=InnoDB;
      		 
      insert into t1 values (1),(1),(2),(3);
      		 
       
      		 
      MariaDB [test]> analyze table t1;
      		 
      +---------+---------+----------+-----------------------------------------+
      		 
      | Table   | Op      | Msg_type | Msg_text                                |
      		 
      +---------+---------+----------+-----------------------------------------+
      		 
      | test.t1 | analyze | status   | Engine-independent statistics collected |
      		 
      | test.t1 | analyze | status   | OK                                      |
      		 
      +---------+---------+----------+-----------------------------------------+
      		 
       
      		 
      alter table t1 change a b int;
      		 
       
      		 
      MariaDB [test]> analyze table t1;
      		 
      +---------+---------+----------+----------------------------------------------------+
      		 
      | Table   | Op      | Msg_type | Msg_text                                           |
      		 
      +---------+---------+----------+----------------------------------------------------+
      		 
      | test.t1 | analyze | status   | Engine-independent statistics collected            |
      		 
      | test.t1 | analyze | Note     | Data truncated for column 'avg_frequency' at row 1 |
      		 
      | test.t1 | analyze | status   | OK                                                 |
      		 
      +---------+---------+----------+----------------------------------------------------+
      		 
       
      		 
      select * from mysql.column_stats;
      		 
      drop table t1;

      So here we see a truncation that happens due
      rounding off (we should suppress this because the user doesn't expects this)
      But we should be throwing a warning if we have an overflow.

      The current situations is like for ANALYZE command we don't make a choice if we want to throw a warning on truncation or not. The above case happens due to the bug MDEV-17778. So this MDEV is about making the choice as to if we want to throw warning or errors for truncation or overflow while calculating the statistics

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          is part of

          Task - A task that needs to be done. MDEV-15253 Default optimizer setting changes for MariaDB 10.4

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

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              psergei Sergei Petrunia
              varun Varun Gupta (Inactive)
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              Dates

                Created:
                Updated:

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