Support --where clause

[kennytm]

Support the --where clause from mysqldump. The condition is applied on all tables.

• The file size of the SQL dump should still be close to the configuration. If we dumped 1000 files of 256 MB each originally, and we use --where to filter out half of the rows, the result should be 500 files of 256 MB each, not 1000 files of 128 MB each.

• If the expression cannot be evaluated, abort and report the error.

• The condition used should be written out for SQL dumps (can be skipped for CSV and binary dumps) like:

  /* WHERE (id > 500) */
  INSERT INTO ...

• Even if all rows are filtered out, it should still generate an SQL file with content:

  /* All data are filtered out by this condition: */
  /* WHERE (id > 500) */

Should work just fine by adding the condition to SELECT *.

Score

• 600