-
Just wanted to codify some of the above:
q)tab:([]sym:-50000?`6;px:50000?10) q)ktab:`sym xkey tab // wanted to show the last record to convince that if kdb // has to search through entire list, no speed gain is evident q)-1#tab sym px --------- obafmn 6 q)-1#ktab sym | px ------| -- obafmn| 6 q)\ts do[100000;select from tab where sym=`obafmn] 2034 66240 q)\ts do[100000;select from ktab where sym=`obafmn] 2051 66240 // below no speed gain, but memory usage is reduced q)\ts do[100000;ktab`obafmn] 2079 960 // however this does mean any other *valid* request would be faster q)rand key ktab sym| kfpfmd q)\ts do[100000;ktab`kfpfmd] 1169 960 // showing point above with grouped attribute applied to keyed column q)gktab:`sym xkey update `g#sym from tab q)\ts do[100000;select from gktab where sym=`obafmn] 89 1808 // final point I wanted to make showing duplicate keys q)`a`a!(1;1) a| 1 a| 1
Thanks and for contributing here.