fix: drop gzip support, improve performance. (#1854)

BREAKING CHANGE

Not gzipping the output more than doubles the throughput for a simple "do nothing" RPC function.

Postgrest's gzip support was surprisingly slow, lacked in configurability, was undocumented and untested.

It was possible to achieve this before by not sending `Accept-Encoding: gzip`, but that turned into a bit of an undocumented gotcha. Most browsers do send it and by default a proxy pass would forward this header. Better to not support gzip at all, further focusing on ensuring Postgrest is a minimal layer over Postgres.

Nginx, or whatever proxy, provides critical options such as min length, vary headers and so forth, and will likely have much better performance as well.

CHANGELOG.md

@@ -36,7 +36,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
  - #1560, Volatile RPC called with GET now returns 405 Method not Allowed instead of 500 - @wolfgangwalther
  - #1604, Change the default logging level to `log-level=error`. Only requests with a status greater or equal than 500 will be logged. If you wish to go back to the previous behaviour and log all the requests, use `log-level=info` - @steve-chavez
  - #1617, Dropped support for PostgreSQL 9.4 - @wolfgangwalther
-
+ - #1854, Dropped undocumented support for gzip compression (which was surprisingly slow and easily enabled by mistake). In some use-cases this makes Postgres up to 3x faster - @aljungberg
+ 
 ## [7.0.1] - 2020-05-18
 
 ### Fixed

src/PostgREST/Middleware.hs

@@ -116,7 +116,6 @@ pgrstFormat minStatus date req status responseSize =
 pgrstMiddleware :: LogLevel -> Wai.Application -> Wai.Application
 pgrstMiddleware logLevel =
     logger
-  . Wai.gzip Wai.def
   . Wai.cors corsPolicy
   . Wai.staticPolicy (Wai.only [("favicon.ico", "static/favicon.ico")])
   where