Re: change default default_toast_compression to lz4?

Hi,

On 2025-11-21 12:11:38 +0100, Peter Eisentraut wrote:
> How about changing the default of default_toast_compression to lz4?
>
> I have seen cases where servers had performance problems and were CPU-bound
> because of pglz TOAST compression, and changing it to lz4 relieved it
> significantly. I suspect many users are leaving easy performance
> improvements on the table by not using this option.

+1 - I also have seen *and* hit this numerous times.

IIRC it makes the tests runs a tad bit faster too.

> I suppose one issue is that lz4 support is not compiled-in by default, but
> in practice most users will have it. The default could be lz4 if lz4
> support is built, otherwise pglz. This would be similar to other parameters
> where the default is the best one depending on the build configuration.

I think we should mark lz4 as a default-required dependency if we change the
default. That way one needs to explicitly opt into a build that won't be
compatible with existing data directories created (due to pre-existing lz4 .

Greetings,

Andres Freund