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  1. MariaDB Server
  2. MDEV-30915

ALTER TABLE .. ALGORITHM=COPY duplicates contents of multiple file table

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      If ALTER is performed with COPY algorithm (explicitly or implicitly) on a CONNECT table with (potentially) multiple underlying files, the contents of the underlying file gets duplicated.

      Maybe it would be happening for non-multiple tables too, but MDEV-30909 (COPY algorithm is not supported) doesn't allow to check it.

      INSTALL SONAME 'ha_connect';
       
      let $MYSQLD_DATADIR= `select @@datadir`;
       
      --write_file $MYSQLD_DATADIR/test/num1.csv
      1
      2
      EOF
       
      CREATE TABLE t (a int NOT NULL) ENGINE=CONNECT TABLE_TYPE=CSV FILE_NAME='num?.csv' MULTIPLE=1;
      SELECT * FROM t;
      ALTER TABLE t FORCE;
      SELECT * FROM t;
       
      ALTER TABLE t FORCE, ALGORITHM=COPY;
      SELECT * FROM t;
       
      --echo # File contents
      --cat_file $MYSQLD_DATADIR/test/num1.csv
       
      # Cleanup
      DROP TABLE t;
      UNINSTALL SONAME 'ha_connect';
      

      10.4 ff3d4395

      ALTER TABLE t FORCE;
      Warnings:
      Warning	1105	This is an outward table, table data were not modified.
      SELECT * FROM t;
      a
      1
      2
      ALTER TABLE t FORCE, ALGORITHM=COPY;
      SELECT * FROM t;
      a
      1
      2
      1
      2
      # File contents
      1
      2
      1
      2
      

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            Unassigned Unassigned
            elenst Elena Stepanova
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              Updated:

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