>
> OK, so your tables all have the same fields (columns), as if you used
> CREATE TABLE new_table ( LIKE some_template_table ) ?


It will contain some other unique columns for each table.

> meaning that they contain NULL values in that field for every record?


what is the  value it may contain i don't know ?? we are not filling any
value !!

>
> > If you drop those columns we will gain any performance or not.....
>
 I need to test... HOW to test the overall performance of database..

> However, I recall hearing that PostgreSQL keeps a null bitmap and doesn't
> use any storage for null fields. If that is correct then you probably won't
> be paying much of a price in disk I/O, but there might still be other costs.
>
if it is sure that it will not make disk I/O then it is ok

>
> I can't help wondering why you have all those useless columns in the
> first place, and why you have so many identically structured tables.
>
these are not useless columns... it should be used to update the owner of
the record, updated time, created and other stuffs, but nobody is using now.


>
> --
> Craig Ringer
>

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