Re: [HACKERS] Custom compression methods

On 12/17/2017 04:32 AM, Robert Haas wrote:
> On Thu, Dec 14, 2017 at 12:23 PM, Tomas Vondra
> <tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>> Can you give an example of such algorithm? Because I haven't seen such
>> example, and I find arguments based on hypothetical compression methods
>> somewhat suspicious.
>>
>> FWIW I'm not against considering such compression methods, but OTOH it
>> may not be such a great primary use case to drive the overall design.
>
> Well it isn't, really. I am honestly not sure what we're arguing
> about at this point. I think you've agreed that (1) opening avenues
> for extensibility is useful, (2) substitution a general-purpose
> compression algorithm could be useful, and (3) having datatype
> compression that is enabled through TOAST rather than built into the
> datatype might sometimes be desirable. That's more than adequate
> justification for this proposal, whether half-general compression
> methods exist or not. I am prepared to concede that there may be no
> useful examples of such a thing.
>

I don't think we're arguing - we're discussing if a proposed patch is
the right design solving relevant use cases.

I personally am not quite convinced about that, for the reason I tried
to explain in my previous messages. I see it as a poor alternative to
compression built into the data type. I do like the idea of compression
with external dictionary, however.

But don't forget that it's not me in this thread - it's my evil twin,
moonlighting as Mr. Devil's lawyer ;-)

--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services