Re: Support of partial decompression for datums

On Fri, Dec 4, 2015 at 9:47 PM, Ildus Kurbangaliev
<i(dot)kurbangaliev(at)postgrespro(dot)ru> wrote:
> Attached patch adds support of partial decompression for datums.
> It will be useful in many cases when extracting part of data is
> enough for big varlena structures.
>
> It is especially useful for expanded datums, because it provides
> storage for partial results.
>
> I have another patch, which removes the 1 Mb limit on tsvector using
> this feature.

-1 for changing the shape of pglz_decompress directly and particularly
use metadata in it. The current format of those routines is close to
what lz4 offers in terms of compression and decompression of a string,
let's not break that we had a time hard enough in 9.5 cycle to get
something clean.

By the way, why don't you compress the multiple chunks and store the
related metadata at a higher level? There is no need to put that in
pglz itself.
--
Michael