Re: [PATCH] Optimize json_lex_string by batching character copying

[Jelte Fennema]

> I wonder why copyable_characters_length is not reset after flushing.

It's not necessary because of the break statement right after. But this part 
of the code was refactored away in John's improved patch that's actually 
merged: 
https://github.com/postgres/postgres/commit/3838fa269c15706df2b85ce2d6af8aacd5611655