Re: Caching number of blocks in relation to avoi lseek. - Mailing list pgsql-hackers

> Hello all,
> 
> While digging the code I found out quite interesting comment in
> src/backend/access/heap/hio.c before function RelationPutHeapTupleAtEnd
> 
>  * Eventually, we should cache the number of blocks in a relation somewhere.
>  * Until that time, this code will have to do an lseek to determine the number
>  * of blocks in a relation.
> 
> As far as I can see there's field rd_nblocks in Relation.
> 
> Question: is this field properly updated? Could it be used instead of RelationGetNumberOfBlocks
> which calls lseek.

Probably should be kept up-to-date.  Currently only vacuum sets it.  It
would have to be kept up-to-date for every INSERT/UPDATE that adds a block.

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