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  1. MariaDB Server
  2. MDEV-6714

mysqldump slow with tables in big databases

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      Description

      On an environment with more thatn 500000 tables, the mysqldump is slow on dumping separate tables.

      mysqldump uses the traditional queries like

      show table status like 'a\_test\_bgtable\_2';
      SHOW TRIGGERS LIKE ''a\_test\_bgtable\_2';
      SHOW TABLES LIKE ''a\_test\_bgtable\_2';
      

      instead of querying information_schema.tables .

      select *
      from information_schema.tables
      where table_schema = 'test_tmp'
      and table_name = 'a_test_bgtable_2';
      

      takes 0.0011s, while

      use test_tmp;
      show tables like 'a\_test\_bgtable\_2';
      

      takes about 10 seconds. This makes the dumps unnecessary slow.

      mysqldump could use the information_schema here (after checking the server version), or the server could detect LIKE-Patterns that can only expand to exactly one table name (because there are no wildcards) and use a more intelligent algorithm internally, e.g. use the implementation of information_schema.tables .

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            • Assignee:
              cvicentiu Vicentiu Ciorbaru
              Reporter:
              ivan.stoykov@skysql.com Stoykov
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              • Created:
                Updated:
                Resolved: