Dictionary inside table

Community Support
1

Hello kdb gurus,

I’m total qbie and can’t figure out how to use basic tables in kdb+. I believe someone with some practical experience can solve the riddle on how to insert Dictionary to the table.

My attempt to create table with dictionary:

xxx:([]
ext_attrs:()/ EXT\_ATTRIBUTE  
);

.u.upd:insert

Test code:

q)m:(8471328`99!(“VWAP”;“Invalid quantity”;“50”))

q)m

847 | “VWAP”

1328| “Invalid quantity”

99 | “50”

Attempt to insert the dictionary to table:

q).u.upd[`xxx;m]

'mismatch

Result:

Failed with some kind of mismatch…

Can someone help me inserting dictionary into table?

If it is possible in q language would it be possible to perform from c.java?

Thanks ;)

P

2

On Tuesday, April 3, 2018 at 6:21:38 AM UTC+1, Pranas Baliuka wrote:

Hello kdb gurus,

I’m total qbie and can’t figure out how to use basic tables in kdb+. I believe someone with some practical experience can solve the riddle on how to insert Dictionary to the table.

My attempt to create table with dictionary:

xxx:(
ext_attrs:()/ EXT_ATTRIBUTE
);

.u.upd:insert

Test code:

q)m:(8471328`99!(“VWAP”;“Invalid quantity”;“50”))

q)m

847 | “VWAP”

1328| “Invalid quantity”

99 | “50”

Attempt to insert the dictionary to table:

q).u.upd[`xxx;m]

'mismatch

Result:

Failed with some kind of mismatch…

Can someone help me inserting dictionary into table?

If it is possible in q language would it be possible to perform from c.java?

Thanks ;)

P

Hi Pranas,

I believe the following will insert your dictionary into your table:

q)xxx:(ext_attrs:())

q).u.upd:insert

q)m:(8471328`99!(“VWAP”;“Invalid quantity”;“50”))

q).u.upd[xxx;enlist[ext_attrs]!enlist m]

,0

q)xxx

ext_attrs

8471328`99!(“VWAP”;“Invalid quantity”;“50”)

As for the q language in c.java try:

.c.k(“.u.upd”,“xxx”,m)

where m is previously constructed following similar examples that can be found here:

http://code.kx.com/q/interfaces/java-client-for-q/

e.g. to publish to a kdb+ consumer, here a kdb+ ticker plant, use

// Assuming a remote schema of

// mytable:(time:timespan$();sym:symbol$();price:float$();size:long$())

Objectrow={new c.Timespan(),“SYMBOL”,new Double(93.5),new Long(300)};

c.k(“.u.upd”,“mytable”,row);

I hope this helps,

Julia  

3

Hi Pranas

I wonder if you actually want a table at all. It looks like you want to associate the dictionary m with the key xxx. A dictionary would do that for you. A namespace is a dictionary. (Remember Kx reserves all 1-character namespaces to its own use.)



q)xa:(enlist)!enlist (::) / extended attributes dictionary</font> <font face='"monospace,' monospace>q).ut.upd:@[xa;;:;]

q).ut.upd[xxx;(847132899!(“VWAP”;“Invalid quantity”;“50”))]
q).ut.upd[yyy;(787149299!(“VWAP”;“Invalid question”;“42”))]

q)xa
| ::
xxx| (847132899!("VWAP";"Invalid quantity";"50"))<br>yyy| (787149299!(“VWAP”;“Invalid question”;“42”))

Note the initialisation of the dictionary. Initialise it as the generic empty dictionary ()!() instead only if every dictionary argument of .ut.upd has the same keys.


Stephen




Stephen Taylor | Librarian | Kx | +44 7713 400852 | stephen@kx.com

4

q)tab:(time:`timestamp$();details:())
q)tab
time details

q)meta tab

c      t f a
time   p
details

q)d:(namelanguage)!(enlist “nks”; enlist `kdb)
q)d
name    | “nks”
language| kdb

q)`tab insert (.z.p;d)
,0
q)tab
time                          details

2018.04.08D10:00:48.240131000 namelanguage!(,“nks”;,`kdb)