On Tue, May 10, 2011 at 3:35 AM, Leonardo Francalanci <m_lists@yahoo.it> wrote:
>> Yes, that seems like a very appealing approach. There is plenty of
>> bit-space available in xinfo, and we could reserve a bit each for
>> nrels, nsubxacts, and nmsgs, with set meaning that an integer count of
>> that item is present and clear meaning that the count is omitted from
>> the structure (and zero). This will probably require a bit of tricky
>> code reorganization so I think it should be done separately from the
>> main patch.
>
> Ok, I'll try and send a patch with this change only.
> BTW xinfo is 32 bit long, but I think only 2 bits are used right now?
> I think I can make it a 8 bits, and add another 8 bits for nrels,
> nsubxacts, and nmsgs and the new thing. That should save
> another 2 bytes, while leaving space for extention. Or we can make
> it a 8 bits only, but only 2 bits would be left "empty" for future
> extentions; I don't know if we care about it...
I don't think making xinfo shorter will save anything, because
whatever follows it is going to be a 4-byte quantity and therefore
4-byte aligned.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
