Postgres set on conflict update

[AlexKomrakov]

Since version 9.5 postgres (9.6 latest) has on conflict update set syntax. This syntax avoids lots of error record in postgres logs (duplicate key error). https://www.postgresql.org/docs/9.5/static/sql-insert.html

[codecov-io]

Codecov Report

Merging #24 into master will decrease coverage by 0.24%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #24      +/-   ##
==========================================
- Coverage    84.1%   83.86%   -0.25%     
==========================================
  Files          44       44              
  Lines        2737     2751      +14     
==========================================
+ Hits         2302     2307       +5     
- Misses        435      444       +9

Impacted Files	Coverage Δ
src/Adapters/PostgreSQL.php	77.5% <100%> (+12.11%)	:arrow_up:
src/Adapters/SQL.php	90.78% <0%> (-3.23%)	:arrow_down:
src/Adapters/Memcached.php	70.46% <0%> (-0.68%)	:arrow_down:
src/Adapters/Couchbase.php	87.41% <0%> (-0.67%)	:arrow_down:

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[matthiasmullie]

Thanks for this PR!

You wouldn't happen to know offhand if there's an easy (and not too intensive/slow) way to detect the PostgreSQL version? Or a fallback alternative for older versions? I also want to keep this working for older PostgreSQL versions where possible.

If not, I can look into it later - just a bit swamped now :)

[matthiasmullie]

This has been merged (https://github.com/matthiasmullie/scrapbook/commit/ee7f2f440030cc1034fea47df5022d2de0617ed1) - thanks!