xkey (set primary key verb)
The verb xkey sets the primary keys in a table.
r:keys xkey table
The left argument is a symbol list of column names, which must belong to the table.
The right argument is a table. If passed by reference, it is updated. If passed by value, a new table is returned.
q)\l trade.q q)keys trade `symbol$() / no primary key q)`sym xkey trade / return table with primary key sym sym| time price size ---| ----------------------- a | 09:30:00.000 10.75 100 q)keys trade / trade has not changed `symbol$() q)`sym xkey `trade / pass trade by reference updates the table in place `trade q)keys trade / sym is now primary key of trade ,`sym
For a complete list of functions, see the kdb+ Function Reference.