| From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: should we add a XLogRecPtr/LSN SQL type? |
| Date: | 2013-12-12 17:20:00 |
| Message-ID: | 20131212172000.GB25303@alap2.anarazel.de |
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| Thread: | |
| Lists: | pgsql-hackers |
Hi,
On 2013-12-12 11:55:51 -0500, Tom Lane wrote:
> I'm not, however, terribly thrilled with the suggestions to add implicit
> casts associated with this type. Implicit casts are generally dangerous.
It's a tradeof. Currently we have the following functions returning LSNs
as text:
* pg_current_xlog_location
* pg_current_xlog_insert_location
* pg_last_xlog_receive_location
* pg_last_xlog_replay_location
one view containing LSNs
* pg_stat_replication
and the following functions accepting LSNs as textual paramters:
* pg_xlog_location_diff
* pg_xlogfile_name
The question is how do we deal with backward compatibility when
introducing a LSN type? There might be some broken code around
monitoring if we simply replace the type without implicit casts. But
just leaving all those as-is seems quite unattractive.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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