Re: currtid_byreloid and currtid_byrelname

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От Gregory Stark
Тема Re: currtid_byreloid and currtid_byrelname
Дата
Msg-id 87ejkcq03g.fsf@oxford.xeocode.com
обсуждение исходный текст
Ответ на Re: currtid_byreloid and currtid_byrelname  (Tom Lane <tgl@sss.pgh.pa.us>)
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"Tom Lane" <tgl@sss.pgh.pa.us> writes:

> Heikki Linnakangas <heikki@enterprisedb.com> writes:
>> In utils/adt/tid.c, there's two mysterious functions with no comments, 
>> and no-one calling them inside backend code AFAICT: currtid_byreloid and 
>> currtid_byrelname. What do they do/did?
>
> IIRC, the ODBC driver uses them, or once did, to deal with
> concurrent-update situations --- it wants to be able to find the
> currently committed version of a row it saw as valid earlier in the
> transaction.  I think it's sort of a client-side version of the
> EvalPlanQual stuff.  Hiroshi probably remembers more.

It could be using currtid_byreloid:
                                                     List of functions  Schema   |  Name   | Result data type |
Argumentdata types | Owner | Language |   Source code    |      Description      
 

------------+---------+------------------+---------------------+-------+----------+------------------+-----------------------pg_catalog
|currtid | tid              | oid, tid            | stark | internal | currtid_byreloid | latest tid of a tuple
 
(1 row)


But how would it use currtid_byrelname?


--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com



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