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  1. MariaDB Server
  2. MDEV-32871

A table is missing inserted entries from concurrent processes

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      I create a db and table using the attached cr.sql.

      Then from my c code, using connector-c, I do:

      SET autocommit=0
      INSERT IGNORE INTO sources(src) VALUES (?)
      START TRANSACTION
      

      And then a lot of:

      INSERT IGNORE INTO sources(src) VALUES ('src-003431-00001')
      

      src is composed of pid and values from 0 to 49. So they are all unique.
      Finally, I do:

      COMMIT
      

      If I run the c code (it creates 10 parallel children), I see:

      select count(id), substr(src,5,6) as sss from sources group by sss;
      +-----------+--------+
      | count(id) | sss    |
      +-----------+--------+
      |        50 | 003430 |
      |        50 | 003431 |
      |        50 | 003432 |
      |        40 | 003433 |
      |        50 | 003434 |
      |        50 | 003435 |
      |        50 | 003436 |
      |        50 | 003437 |
      |        50 | 003438 |
      |        50 | 003439 |
      +-----------+--------+
      

      I.e. Some of pids stored only last 40 values, numbers 0..9 are missing in the table:

      select src from sources where src like '%003433%' order by src ;
      +------------------+
      | src              |
      +------------------+
      | src-003433-00010 |
      | src-003433-00011 |
      | src-003433-00012 |
      | src-003433-00013 |
      | src-003433-00014 |
      | src-003433-00015 |
      | src-003433-00016 |
      | src-003433-00017 |
      | src-003433-00018 |
      | src-003433-00019 |
      | src-003433-00020 |
      | src-003433-00021 |
      | src-003433-00022 |
      | src-003433-00023 |
      | src-003433-00024 |
      | src-003433-00025 |
      | src-003433-00026 |
      | src-003433-00027 |
      | src-003433-00028 |
      | src-003433-00029 |
      | src-003433-00030 |
      | src-003433-00031 |
      | src-003433-00032 |
      | src-003433-00033 |
      | src-003433-00034 |
      | src-003433-00035 |
      | src-003433-00036 |
      | src-003433-00037 |
      | src-003433-00038 |
      | src-003433-00039 |
      | src-003433-00040 |
      | src-003433-00041 |
      | src-003433-00042 |
      | src-003433-00043 |
      | src-003433-00044 |
      | src-003433-00045 |
      | src-003433-00046 |
      | src-003433-00047 |
      | src-003433-00048 |
      | src-003433-00049 |
      +------------------+
      

      Is this a bug in my program (attached) or the db? If I look into the general log, I see the inserts which apparently did not get into the table:

      grep src-003433 /tmp/glog
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00000')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00000')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00000')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00000')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00000')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00001')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00002')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00003')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00004')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00005')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00006')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00007')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00008')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00009')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00010')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00010')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00011')
                          24 Execute  INSERT IGNORE INTO sources(src) VALUES ('src-003433-00012')
      

      Note also the repeated inserts. They come from a deadlock, so I repeat the exec in a loop (see the code).

      Attachments

        1. cr.sql
          0.3 kB
        2. db.c
          3 kB

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          People

            serg Sergei Golubchik
            jirislaby Jiri Slaby
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            Dates

              Created:
              Updated:

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