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  1. MariaDB Server
  2. MDEV-8928

Queries on information_schema.TABLES with invalid SPIDER table causes problems

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      SELECT * FROM mysql.spider_tables \G
      *************************** 1. row ***************************
                     db_name: x
                  table_name: s
                     link_id: 0
                    priority: 1000000
                      server: NULL
                      scheme: NULL
                        host: 127.0.0.1
                        port: NULL
                      socket: NULL
                    username: root
                    password: proot
                      ssl_ca: NULL
                  ssl_capath: NULL
                    ssl_cert: NULL
                  ssl_cipher: NULL
                     ssl_key: NULL
      ssl_verify_server_cert: 0
                default_file: NULL
               default_group: NULL
                 tgt_db_name: NULL
              tgt_table_name: NULL
                 link_status: 1
      1 row in set (0.00 sec)

      SHOW PROCESSLIST;
      +----+------+-------------------+------+---------+------+----------------------+-----------------------------------------+----------+
      | Id | User | Host              | db   | Command | Time | State                | Info                                    | Progress |
      +----+------+-------------------+------+---------+------+----------------------+-----------------------------------------+----------+
      | 32 | root | 172.17.42.1:35121 | test | Query   |    3 | After opening tables | SELECT * FROM information_schema.TABLES |    0.000 |
      | 45 | root | 172.17.42.1:35145 | test | Query   |    0 | init                 | SHOW PROCESSLIST                        |    0.000 |
      | 47 | root | 127.0.0.1:43968   | x    | Query   |    3 | After opening tables | show table status from `x` like 's'     |    0.000 |
      +----+------+-------------------+------+---------+------+----------------------+-----------------------------------------+----------+

      Connection 32 will wait forever or for a long time (not sure). I can KILL connection 47, but connection 32 will say that MySQL server has gone away.
      Connection 47 will also block:

      • DROP TABLE x.s
      • FLUSH TABLES
      • maybe others...

      The solution is not that hard (KILL 47; DROP TABLE x.s), but I think that SPIDER should detect the problem and return an error to the user. Or maybe SPIDER shouldn't open that connection at all.

      If this is not a bug, please consider it as a feature request.

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            nayuta-yanagisawa Nayuta Yanagisawa (Inactive)
            f_razzoli Federico Razzoli
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              Created:
              Updated:
              Resolved:

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