What are some of the hard limits of kdb I should know about?

  • no more than 2GB over IPC
  • number of tables mapped is limited by number of file descriptors allowed by OS
  • maximum of 32 global references per function
  • maximum of 23 local variables per function
  • maximum of 96 constants within a function
  • enums are limited to 57 – (type values 20h to 76h)
  • 4096 maximum compressed files open (for versions earlier than 3.1T2013.02.21)
  • 999 nested columns in splayed table
  • 1022 maximum incoming network connections
  • maximum of eight function parameters
  • maximum number of mapped nested columns 1024
  • maximum number of active `g# indices 1024
  • maximum branch (if; do; while; $[]) distance is 255 byte codes away (from PC to PC+255bytes!) – if you get a ‘branch error, you have to break the code up into smaller pieces

See also: error codes