Re: [HACKERS] getting rid of SnapshotNow

(2013/07/19 22:03), Andres Freund wrote:
> On 2013-07-19 08:57:01 +0900, Inoue, Hiroshi wrote:
>>>> I had the idea they were used for a client-side implementation of WHERE
>>>> CURRENT OF.  Perhaps that's dead code and could be removed entirely?
>>>
>>> It's been reported that ODBC still uses them.
>>
>> Though PostgreSQL's TID is similar to Orale's ROWID, it is transient
>> and changed after update operations unfortunately. I implemented
>> the currtid_xx functions to supplement the difference. For example
>>
>>     currtid(relname, original tid)
>>
>> (hopefully) returns the current tid of the original row when it is
>> updated.
>
> That is only guaranteed to work though when you're in a transaction old
> enough to prevent removal of the old or intermediate row versions. E.g.

Yes it's what I meant by (hopefully).
At the time when I implemented currtid(), I was able to use TIDs in
combination with OIDs.

regards,
Hiroshi Inoue