Re: [HACKERS] pg_lsn cast to/from int8
On Tue, Jan 26, 2016 at 4:58 PM, Craig Ringer wrote: > On 26 January 2016 at 22:07, Magnus Hagander wrote: > > >> In this case, mostly legacy compatibility. Making an app that works with >> versions that don't have pg_lsn have a nice path forward to the modern >> world. Being able to cast from pg_lsn to int8 can also make it easier to >> work with the values in the client application, though I don't need that >> for this particular one. >> >> > Wouldn't we need a uint8 type for that? > > I guess we could just show people negative LSNs if the high bit is set > (that being rather unlikely) but still... > Yes, in theory. Though the likelihood of actually reaching that... It would probably be OK to just throw an error if the high bit is actually set. -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/
Re: [HACKERS] pg_lsn cast to/from int8
On 26 January 2016 at 22:07, Magnus Hagander wrote: > In this case, mostly legacy compatibility. Making an app that works with > versions that don't have pg_lsn have a nice path forward to the modern > world. Being able to cast from pg_lsn to int8 can also make it easier to > work with the values in the client application, though I don't need that > for this particular one. > > Wouldn't we need a uint8 type for that? I guess we could just show people negative LSNs if the high bit is set (that being rather unlikely) but still... -- Craig Ringer http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
Re: [HACKERS] pg_lsn cast to/from int8
On Tue, Jan 26, 2016 at 3:00 PM, Andres Freund wrote: > On 2016-01-26 14:56:21 +0100, Magnus Hagander wrote: > > Is there a reason we don't have casts between int8 and pg_lsn? AFAICT it > > works fine if I create the cast manually... Is it because of > > signed/unsigned if people have really really many transactions? > > What for do you want that cast? Yes, the internally mostly share the > representation, but other than that, I don't really see why it's > interesting? > In this case, mostly legacy compatibility. Making an app that works with versions that don't have pg_lsn have a nice path forward to the modern world. Being able to cast from pg_lsn to int8 can also make it easier to work with the values in the client application, though I don't need that for this particular one. -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/
Re: [HACKERS] pg_lsn cast to/from int8
On 2016-01-26 14:56:21 +0100, Magnus Hagander wrote: > Is there a reason we don't have casts between int8 and pg_lsn? AFAICT it > works fine if I create the cast manually... Is it because of > signed/unsigned if people have really really many transactions? What for do you want that cast? Yes, the internally mostly share the representation, but other than that, I don't really see why it's interesting? -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
