Re: Exposing the Xact commit order to the user - Mailing list pgsql-hackers

From Greg Stark
Subject Re: Exposing the Xact commit order to the user
Date
Msg-id AANLkTinqlFtvpS-45F354qVSBJ49MHjBRG1ucMc75HZo@mail.gmail.com
Whole thread Raw
In response to Exposing the Xact commit order to the user  (Jan Wieck <JanWieck@Yahoo.com>)
Responses Re: Exposing the Xact commit order to the user
Re: Exposing the Xact commit order to the user
List pgsql-hackers
On Sun, May 23, 2010 at 9:21 PM, Jan Wieck <JanWieck@yahoo.com> wrote:
> Each record of the Transaction Commit Info consists of
>
>     txid          xci_transaction_id
>     timestamptz   xci_begin_timestamp
>     timestamptz   xci_commit_timestamp
>     int64         xci_total_rowcount
>

So I think you're going about this backwards.

Instead of discussing implementation I think you should start with the
API the replication system needs. In particular I'm not sure you
really want a server-side query at all. I'm wondering if you wouldn't
be better off with a public machine-parsable text format version of
the WAL. Ie, at the same time as writing out all the nitty gritty to
the binary wal we would write out a summary of public data to an xml
version containing just parts of the data stream that we can promise
won't change, such as transaction id, lsn, timestamp.

--
greg


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