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databasetime-serieskdb

Is it possible to craete a table with only one emtpy primary key column in Kdb+?

I tried to create an empty table with only one column, and this column is set as primary key. But I failed, until there is another column within table.

Is it supposed not to create an emtpy table with only one keyed column ?

// this failed
et :([pk:`symbol$()])
// this makes, means simgle emtpy key column is available
emptyTable:([primaryKey:`symbol$()] c1:())
// this makes too, means single empty column is available
t1:([]c1:())
Solution

  • A keyed table is not a table, it is a dictionary mapping a table of key records to a table of value records. It has type 99h. You can see how the keyed table is formed using parse

    q)parse "([pk:`symbol$()]c1:())"
!
(+:;(!;,,`pk;(enlist;($;,`symbol;()))))
(+:;(!;,,`c1;(enlist;())))

    Using "!" to create a dictionary requires two arguments otherwise a parse error is returned