-
The sym file contains enumerated symbols for an symbol column in any table.
The reason you can select it is that if q fails to find a column of that name it will try to use a global variable , which sym will be.
q)`:tab/ set .Q.en[`:.] ([] a:1 2 3;b:`a`b`c) `:tab/ q)tab:get `:tab/ q)tab a b --- 1 a 2 b 3 c q)select sym from tab sym --- a b c q)sym //sym is in memory `a`b`c 2 q)nonsense:`one`two`three q)select nonsense from tab //nonsense is not a column but a global variable nonsense -------- one two three q)delete sym from `. /delete sym from memory `. q)tab / now any sym columns show indexes as they cannot resolve their text a b --- 1 0 2 1 3 2
Review some documentation on enumeration and on disk data:
- https://code.kx.com/q/basics/enumerations/
- https://code.kx.com/q4m3/14_Introduction_to_Kdb+/#1428-working-with-sym-files