Thread

1. Unique index using hash?

   ocie@paracel.com — 1998-03-17T01:45:15Z

   I was playing around with my latest compile and tried to make a unique
   index on two columns, using a hash method.  Both of these (more than
   one column and unique) are currently not allowed for hash indexes.
   
   I thought about this for a bit and realized that making a NESTED hash
   index (index on a and b also serves as an index on a) would be a
   trick, but allowing the unique clause should not be a problem.
   
   Therefore, I would like to try implementing unique constraints on hash
   indexes.  Has this come up before?  Are there any reasons not to
   support this?  As far as I understand, specifying an index method is
   non standard (above and beyond standard) to begin with.
   
   Ocie Mitchell
   
   
   

2. Re: [HACKERS] Unique index using hash?

   Bruce Momjian <maillist@candle.pha.pa.us> — 1998-03-17T03:02:49Z

   > 
   > I was playing around with my latest compile and tried to make a unique
   > index on two columns, using a hash method.  Both of these (more than
   > one column and unique) are currently not allowed for hash indexes.
   > 
   > I thought about this for a bit and realized that making a NESTED hash
   > index (index on a and b also serves as an index on a) would be a
   > trick, but allowing the unique clause should not be a problem.
   > 
   > Therefore, I would like to try implementing unique constraints on hash
   > indexes.  Has this come up before?  Are there any reasons not to
   > support this?  As far as I understand, specifying an index method is
   > non standard (above and beyond standard) to begin with.
   > 
   
   It is on the TODO list:
   
   	* add UNIQUE capability to non-btree indexes
   
   
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