On 2013-04-25 23:07:02 -0400, Peter Eisentraut wrote:
> I'm not sure who is supposed to be able to read this sort of stuff:
>
> Latest checkpoint's NextXID: 0/7575
> Latest checkpoint's NextOID: 49152
> Latest checkpoint's NextMultiXactId: 7
> Latest checkpoint's NextMultiOffset: 13
> Latest checkpoint's oldestXID: 1265
> Latest checkpoint's oldestXID's DB: 1
> Latest checkpoint's oldestActiveXID: 0
> Latest checkpoint's oldestMultiXid: 1
> Latest checkpoint's oldestMulti's DB: 1
>
> Note that these symbols don't even correspond to the actual symbols used
> in the source code in some cases.
>
> The comments in the pg_control.h header file use much more pleasant
> terms, which when put to use would lead to output similar to this:
>
> Latest checkpoint's next free transaction ID: 0/7575
> Latest checkpoint's next free OID: 49152
> Latest checkpoint's next free MultiXactId: 7
> Latest checkpoint's next free MultiXact offset: 13
> Latest checkpoint's cluster-wide minimum datfrozenxid: 1265
> Latest checkpoint's database with cluster-wide minimum datfrozenxid: 1
> Latest checkpoint's oldest transaction ID still running: 0
> Latest checkpoint's cluster-wide minimum datminmxid: 1
> Latest checkpoint's database with cluster-wide minimum datminmxid: 1
>
> One could even rearrange the layout a little bit like this:
>
> Control data as of latest checkpoint:
> next free transaction ID: 0/7575
> next free OID: 49152
I have to admit I don't see the point. None of those values is particularly
interesting to anybody without implementation level knowledge and those
will likely deal with them just fine. And I find the version with the
shorter names far quicker to read.
The clarity win here doesn't seem to be worth the price of potentially
breaking some tools.
Greetings,
Andres Freund
-- Andres Freund http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services