Re: pglz performance

Hi,

On 05/08/2019 00:15, Andres Freund wrote:
> Hi,
> 
> On 2019-08-04 17:53:26 +0200, Petr Jelinek wrote:
>>> 5) I wonder why compression_algorithm is defined as PGC_SIGHUP. Why not
>>> to allow users to set it per session? I suppose we might have a separate
>>> option for WAL compression_algorithm.
>>>
>>
>> Yeah I was thinking we might want to change wal_compression to enum as well.
>> Although that complicates the code quite a bit (the caller has to decide
>> algorithm instead compression system doing it).
> 
> Isn't that basically required anyway? The WAL record will need to carry
> information about the type of compression used, independent of
> PGC_SIGHUP/PGC_USERSET, unless you want to make it an initdb option or
> something super heavyweight like that.
> 

It carries that information inside the compressed value, like I said in 
the other reply, that's why the extra byte.

-- 
Petr Jelinek
2ndQuadrant - PostgreSQL Solutions for the Enterprise
https://www.2ndQuadrant.com/