Re: Different compression methods for FPI

On 16/06/2021 11:17, Andrey Borodin wrote:
>> 16 июня 2021 г., в 12:18, Michael Paquier <michael@paquier.xyz> написал(а):
>>   Among the
>> remaining two I would be tempted to choose LZ4.  That's consistent
>> with what toast can use now.
> 
> I agree that allowing just lz4 - is already a huge step ahead.
> But I'd suggest supporting zstd as well. Currently we only compress 8Kb chunks and zstd had no runaway to fully
unwrapit's potential.
 
> In WAL-G we observed ~3x improvement in network utilisation when switched from lz4 to zstd in WAL archive
compression.

Hmm, do we currently compress each block in a WAL record separately, for 
records that contain multiple full-page images? That could make a big 
difference e.g. for GiST index build that WAL-logs 32 pages in each 
record. If it helps the compression, we should probably start 
WAL-logging b-tree index build in larger batches, too.

- Heikki