Re: Patch: raise default for max_wal_segments to 1GB

On 03/03/2015 08:31 PM, Josh Berkus wrote:
> On 03/03/2015 10:29 AM, Heikki Linnakangas wrote:
>> On 03/03/2015 08:21 PM, Josh Berkus wrote:
>>> On 03/03/2015 10:15 AM, Josh Berkus wrote:
>>>> On 03/02/2015 11:25 PM, Heikki Linnakangas wrote:
>>>>> I propose that we remove the comment from max_wal_size, and also remove
>>>>> the "in milliseconds" from wal_receiver_timeout and
>>>>> autovacuum_vacuum_cost_delay.
>>>>
>>>> +1
>>>>
>>>
>>> Actually, let's be consistent about this.  It makes no sense to remove
>>> unit comments from some settings which accept ms but not others.
>>>
>>> Do we want to remove unit comments from all settings which accept
>>> "MB,GB" or "ms,s,min"?  There's more than a few.  I'd be in favor of
>>> this, but seems like (a) it should be universal, and (b) its own patch.
>>
>> I think it's a good rule that if the commented-out default in the sample
>> file does not contain a unit, then the base unit is in the comment.
>> Otherwise it's not. For example:
>>
>> #shared_buffers = 32MB            # min 128kB
>>                      # (change requires restart)
>>
>> The base unit is BLCKSZ, i.e. 8k, but usually people will usually use
>> MB/GB. And that is evident from the default value, 32MB, so there's no
>> need to mention it in the comment.
>>
>> #tcp_keepalives_idle = 0        # TCP_KEEPIDLE, in seconds;
>>                      # 0 selects the system default
>>
>> Here it's not obvious what the unit should be from the default itself.
>> So the comment says it's "in seconds".
>
> Sure.  Although, do we take (s) for tcp_keepalives_idle?  Or only an INT?

It's a "time unit", so you can say "10s" or "10000ms". If you don't 
specify a unit, it implies seconds.

- Heikki