Need indexes on empty tables for good performance ?

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От Lenard, Rohan (Rohan)
Тема Need indexes on empty tables for good performance ?
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Msg-id 2773CAC687FD5F4689F526998C7E4E5F43F392@au3010avexu1.global.avaya.com
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Ответы Re: Need indexes on empty tables for good performance ?  (Bruno Wolff III <bruno@wolff.to>)
Re: Need indexes on empty tables for good performance ?  ("Thomas F. O'Connell" <tfo@sitening.com>)
Re: Need indexes on empty tables for good performance ?  (Chris Travers <chris@metatrontech.com>)
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I've read that indexes aren't used for COUNT(*) and I've noticed (7.3.x) with EXPLAIN that indexes never seem to be used on empty tables - is there any reason to have indexes on empty tables, or will postgresql never use them.
 
This is not as silly as it sounds - with table inheritance you might have table children with the data and a parent that is empty.  It'd be nice to make sure postgresql knows to never really look at the parent - especially is you don't know the names of all the children ..
 
Thoughts ?
 
thx,
  Rohan

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