Outgoing compression

Community Support
1

Is it possible to configure outgoing compression on calls coming into and going out of the kdb+ server?

Preferably over WebSockets?

2

it’s automatic for ipc protocol when

  1. uncompressed data is > 2000 bytes

  2. not a localhost connection

  3. compresses to <.5*original

For investigation, you can use -8!x to serialize, and -18!x to serialize with compression; -9!x will deserialize both of those results.

Websockets - there’s a compression standard (per message compression using deflate) that we could build-in, transparent to users, if there’s enough demand. Chrome already appears to support it.

3

Thanks Charles … I’m new to kdb+ care to share some simple examples of how to use

 -8!x

-18!x

-9lx

4

Btw, you can’t control the compression with those commands - they’re merely there to help in things like debug, or if you happen to require that functionlity of serialization outside of ipc.

-8!x serializes object x to a byte vector without using compression. These are the exact bytes (other than msg type) that would be sent down the socket. e.g.

q)-8!ab`c

0x01000000140000000b0003000000610062006300

-18!x is the same except it will attempt compression

q)-18!2001#0

0x010001009a000000963e0000c80700d10700000000ff00ffff00ff00ff00ff00ff0…

-9!x deserializes that stream, e.g.

q)-9!0x01000000140000000b0003000000610062006300

ab`c

there’s more info on ipc formats etc here

http://code.kx.com/wiki/Reference/ipcprotocol