Re: [HACKERS] Pluggable storage

Hi,

On 6/21/17 9:47 PM, Robert Haas wrote:
...>
> like int8 or numeric, it won't work at all.  Even for other things,
> it's going to cause problems because the bit patterns won't be what
> the code is expecting; e.g. bitmap scans care about the structure of
> the TID, not just how many bits it is.  (Due credit: Somebody, maybe
> Alvaro, pointed out this problem before, at PGCon.) 

Can you elaborate a bit more about this TID bit pattern issues? I do 
remember that not all TIDs are valid due to safeguards on individual 
fields, like for example
    Assert(iptr->ip_posid < (1 << MaxHeapTuplesPerPageBits))

But perhaps there are some other issues?

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services