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<chapter id="maintenance">
just <command>VACUUM</command>, marks expired data in tables and
indexes for future reuse; it does <emphasis>not</emphasis> attempt
to reclaim the space used by this expired data unless the space is
- at the end of the table and an exclusive lock can be obtained easily
- on the table. Unused space at the start or middle of the file does
+ at the end of the table and an exclusive table lock can be easily
+ obtained. Unused space at the start or middle of the file does
not result in the file being shortened and space returned to the
operating system. This variant of <command>VACUUM</command> can be
run concurrently with normal database operations.