Re: Compressed TOAST Slicing

On Mar 12, 2019, at 9:45 AM, Paul Ramsey <pramsey@cleverelephant.ca> wrote:

On Mar 12, 2019, at 9:13 AM, Andres Freund <andres@anarazel.de> wrote:

On 2019-03-12 14:42:14 +0900, Michael Paquier wrote:

On Mon, Mar 11, 2019 at 08:38:56PM +0000, Regina Obe wrote:

I tested on windows mingw64 (as of a week ago) and confirmed the
patch applies cleanly and significantly faster for left, substr
tests than head. 

int32
pglz_decompress(const char *source, int32 slen, char *dest,
-                               int32 rawsize)
+                               int32 rawsize, bool is_slice)

The performance improvements are nice, but breaking a published API is
less nice particularly since some work has been done to make pglz more
plugabble (see 60838df9, guess how wrote that).

I don't think that should stop us from breaking the API. You've got to
do quite low level stuff to need pglz directly, in which case such an
API change should be the least of your problems between major versions.

I was going to say that the function is only used twice in the code base, but I see it’s now used four times. So maybe leave the old signature in place and add the new one for my purposes after all. Though with only four internal calls, I am guessing Michael is more concerned about external users than with internal ones?