Re: [HACKERS] getting rid of SnapshotNow

Alvaro Herrera <alvherre@2ndquadrant.com>

From: Alvaro Herrera <alvherre@2ndquadrant.com>

To: Robert Haas <robertmhaas@gmail.com>

Cc: Tom Lane <tgl@sss.pgh.pa.us>, Noah Misch <noah@leadboat.com>, pgsql-hackers@postgresql.org, pgsql-odbc@postgresql.org

Date: 2013-07-19T17:20:17Z

Lists: pgsql-hackers

Robert Haas escribió:

> 4. If we use GetActiveSnapshot, all the comments about about a fresh
> MVCC snapshot still apply.  However, the snapshot in question could be
> even more stale, especially in repeatable read or serializable mode.
> However, this might be thought a more consistent behavior than what we
> have now.  And I'm guessing that this function is typically run as its
> own transaction, so in practice this doesn't seem much different from
> an MVCC snapshot, only cheaper.
> 
> At the moment, I dislike #2 and slightly prefer #4 to #3.

+1 for #4, and if we ever need more then we can provide a non-default
way to get at #2.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
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