Re: zstd compression for pg_dump

On 4/5/23 21:42, Tomas Vondra wrote:
> On 4/4/23 05:04, Justin Pryzby wrote:
>> On Mon, Apr 03, 2023 at 11:26:09PM +0200, Tomas Vondra wrote:
>>> On 4/3/23 21:17, Justin Pryzby wrote:
>>>> On Sat, Apr 01, 2023 at 10:26:01PM +0200, Tomas Vondra wrote:
>>>>>> Feel free to mess around with threads (but I'd much rather see the patch
>>>>>> progress for zstd:long).
>>>>>
>>>>> OK, understood. The long mode patch is pretty simple. IIUC it does not
>>>>> change the format, i.e. in the worst case we could leave it for PG17
>>>>> too. Correct?
>>>>
>>>> Right, libzstd only has one "format", which is the same as what's used
>>>> by the commandline tool. zstd:long doesn't change the format of the
>>>> output: the library just uses a larger memory buffer to allow better
>>>> compression. There's no format change for zstd:workers, either.
>>>
>>> OK. I plan to do a bit more review/testing on this, and get it committed
>>> over the next day or two, likely including the long mode. One thing I
>>> noticed today is that maybe long_distance should be a bool, not int.
>>> Yes, ZSTD_c_enableLongDistanceMatching() accepts int, but it'd be
>>> cleaner to cast the value during a call and keep it bool otherwise.
>>
>> Thanks for noticing. Evidently I wrote it using "int" to get the
>> feature working, and then later wrote the bool parsing bits but never
>> changed the data structure.
>>
>> This also updates a few comments, indentation, removes a useless
>> assertion, and updates the warning about zstd:workers.
>>
>
> Thanks. I've cleaned up the 0001 a little bit (a couple comment
> improvements), updated the commit message and pushed it. I plan to take
> care of the 0002 (long distance mode) tomorrow, and that'll be it for
> PG16 I think.

I looked at the long mode patch again, updated the commit message and
pushed it. I was wondering if long_mode should really be bool -
logically it is, but ZSTD_CCtx_setParameter() expects int. But I think
that's fine.

I think that's all for PG16 in this patch series. If there's more we
want to do, it'll have to wait for PG17 - Justin, can you update and
submit the patches that you think are relevant for the next CF?

regards

--
Tomas Vondra
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