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2: Dynamic Load

Load C shared objects

fs 2: (cfn;rnk)    2:[fs;(cfn;rnk)]


  • fs is a file symbol
  • cfn is the name of a C function (symbol)
  • rnk its rank (int)

returns a function that calls it.

Suppose we have a C function in with the prototype

K q_read_cycles_of_this_cpu(K x);

assign it to read_cycles:

read_cycles:`cpu 2:(`q_read_cycles_of_this_cpu;1)

If the shared library, as passed, does not exist, kdb+ will try to load it from $QHOME/os, where os is the operating system and architecture acronym, e.g. l64, w64, etc.

If using a relative path which does not resolve to reside under $QHOME/os, ensure that LD_LIBRARY_PATH contains the required absolute search path for that library. (On Windows, use PATH instead of LD_LIBRARY_PATH.)

Since 3.6 2018.08.24 loading shared libraries via 2: resolved to a canonical path prior to load via the OS. This caused issues for libs whose run-time path was relative to a sym-link. From 4.1t 2024.01.11 it resolves to an absolute path only, without resolving sym-links.

File system
Using C/C++ functions