Repository warning

Hi,we met a problem when we tried to unarchive one repository.It is said there were some warnings.We used the check tool of repository to check it.In the detailed report,we could see the information below.

Checking other data integrity...

$$$ Warning(1329): Table A2i_20 needs compacting(IdMax=236, IdCount=165).

$$$ Warning(1329): Table A2i_21 needs compacting(IdMax=119, IdCount=30).

$$$ Warning(1329): Table A2i_22 needs compacting(IdMax=122, IdCount=30).

How did the warning happen?Could we fix it?How to fix?Thanks.