Re: Preventing index scans for non-recoverable index AMs

It would be perfectly reasonable to add an amisrecoverable like Simon  
described. It could automatically set indisvalid to false after a  
crash and treat the index as if indisvalid is false during recovery.  
That would be a lot smoother and safer than what we have now.

It might even be possible to do this with a new wal record type so it  
only happens if there was a write to the index. I imagine most users  
who read that warning and use hash indexes anyways are using them on  
read-only tables where they know it's safe.



-- 
Greg


On 18 Dec 2008, at 07:51, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com > wrote:

> Pavan Deolasee wrote:
>> BTW, if there is no proven case where hash index works significantly
>> better than btree (that's what the doc says), why not just completely
>> abandon it ?
>
> That has been considered many times, see archives. I believe the  
> changes done in 8.4 actually made it faster for some cases. And as  
> Kenneth pointed out hash indexes can handle keys larger than 1/3 of  
> page size, that b-tree can't.
>
> -- 
>  Heikki Linnakangas
>  EnterpriseDB   http://www.enterprisedb.com
>
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