qrapidjson

A faster JSON serialiser for kdb+/q (uses RapidJSON).

Behavior is similar to the builtin .j.j, differing in:

• The serialisation of infinity (eg: 0w or 0wj) will become "Inf" or "-Inf" per relaxed JSON spec
• The precision of serialisation of doubles and floats is left to RapidJSON (rather than \P)
• Keyed tables are serialised as correct JSON (as if they were a normal table)

Build

You may need to run git submodule update --init --recursive the once to get the rapidjson sources.

$ make {m32,m64,l32,l64}
$ cp qrapidjson_{m32,m64,l32,l64}.so /path/to/q/bin

Use

q) tojson: (`$"qrapidjson_m64") 2:(`tojson;1); / change m64 to appropriate platform
q) tojson `a`b`c!(1 2 3) / returns a string

NOTE: You might need to set DYLD_LIBRARY_PATH or LD_LIBRARY_PATH environment variables (Mac and Linux respectively) to the directory where the .so lives before running q.

Performance Benchmark

A completely synthetic example, demonstrating ~48x speed improvement:

q)show t: ([] sym: enlist `Symbol; str: enlist "String"; float: enlist 1.23456789; int: enlist 12345678; date: 2000.01.01; dict: (enlist (`a`b`c!(1 2 3))))
sym    str      float    int      date       dict
---------------------------------------------------------
Symbol "String" 1.234568 12345678 2000.01.01 `a`b`c!1 2 3

q)-1 .j.j t;
[{"sym":"Symbol","str":"String","float":1.234568,"int":12345678,"date":"2000-01-01","dict":{"a":1,"b":2,"c":3}}]

q)-1 tojson t;
[{"sym":"Symbol","str":"String","float":1.23456789,"int":12345678,"date":"2000-01-01","dict":{"a":1,"b":2,"c":3}}]

q)\t .j.j 100000#t
3963

q)\t tojson 100000#t
81

Licence

LGPLv3. See LICENSE and COPYING.LESSER.

Copyright (c) 2016 Lucas Martin-King.

Other parts of this software (eg: RapidJSON) are covered by other licences.