Re: walprotocol.h vs frontends

On 11-08-15 12:33 PM, Peter Geoghegan wrote:
> On 15 August 2011 16:56, Steve Singer<ssinger@ca.afilias.info>  wrote:
>> This would mean that anyone using the floating point timestamps today won't
>> be able to use pg_upgrade to upgrade to whichever version we remove them
>> from.  8.3 had float based timestamps as the default and I suspect many
>> installations with the default 8.3 settings have been upgraded via
>> pg_upgrade to 9.0 built the old timestamps representation.
>
> Really? I find that slightly surprising, considering that a quick look
> at master's timestamp.c suggests that the choice to use the in64
> representation over the double representation is entirely a case of
> compile time either/or. There is no apparent fall-back to the double
> representation available to binaries built without
> --disable-integer-datetimes.
>

I *think* the default on 8.3 was float based timestamps.  If you want to 
upgrade a system running 8.3 (that uses float based timestamps) in 
using pg_upgrade you must compile 9.0 (or 8.4 or 9.1) with 
--disable-integer-datetimes.  If at some point in the future you then 
want to upgrade to 9.2 with pg_upgrade you will again need to build 9.2 
with --disable-integer-datetimes.    If we remove the code for floating 
point representations of datetime then you won't be able to do that.


Steve