Re: Redesigning checkpoint_segments

On 02/04/2015 11:41 PM, Josh Berkus wrote:
> On 02/04/2015 12:06 PM, Robert Haas wrote:
>> On Wed, Feb 4, 2015 at 1:05 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>>> Let me push "max_wal_size" and "min_wal_size" again as our new parameter
>>> names, because:
>>>
>>> * does what it says on the tin
>>> * new user friendly
>>> * encourages people to express it in MB, not segments
>>> * very different from the old name, so people will know it works differently
>>
>> That's not bad. If we added a hard WAL limit in a future release, how
>> would that fit into this naming scheme?
>
> Well, first, nobody's at present proposing a patch to add a hard limit,
> so I'm reluctant to choose non-obvious names to avoid conflict with a
> feature nobody may ever write. There's a number of reasons a hard limit
> would be difficult and/or undesirable.
>
> If we did add one, I'd suggest calling it "wal_size_limit" or something
> similar. However, we're most likely to only implement the limit for
> archives, which means that it might acually be called
> "archive_buffer_limit" or something more to the point.

Ok, I don't hear any loud objections to min_wal_size and max_wal_size,
so let's go with that then.

Attached is a new version of this. It now comes in four patches. The
first three are just GUC-related preliminary work, the first of which I
posted on a separate thread today.

- Heikki