Re: Teach pg_receivewal to use lz4 compression

On Fri, Nov 19, 2021 at 7:37 AM Michael Paquier <michael(at)paquier(dot)xyz> wrote:

> On Thu, Nov 18, 2021 at 07:54:37PM +0530, Jeevan Ladhe wrote:
> > In dir_open_for_write() I observe that we are writing the header
> > and then calling LZ4F_compressEnd() in case there is an error
> > while writing the buffer to the file, and the output buffer of
> > LZ4F_compressEnd() is not written anywhere. Why should this be
> > necessary? To flush the contents of the internal buffer? But, then we
> > are calling LZ4F_freeCompressionContext() immediately after the
> > LZ4F_compressEnd() call. I might be missing something, will be
> > happy to get more insights.
>
> My concern here was symmetry, where IMO it makes sense to have a
> compressEnd call each time there is a successful compressBegin call
> done for the LZ4 state data, as there is no way to know if in the
> future LZ4 won't change some of its internals to do more than just an
> internal flush.
>

Fair enough. But, still I have a doubt in mind what benefit would that
really bring to us here, because we are immediately also freeing the
lz4buf without using it anywhere.

Regards,
Jeevan