| From: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com> |
| Cc: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Pluggable storage |
| Date: | 2017-06-22 21:27:11 |
| Message-ID: | 5863132d-a436-321b-6ef9-7c5173bd8ef3@2ndquadrant.com |
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| Thread: | |
| Lists: | pgsql-hackers |
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
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