Does kdb+ support views? Materialised views?

[Matt]

Hi,

I am more familiar with other standard database systems and I can’t seem to find any mention of using views in kdb+.

Does kdb+ have views?

[Ryan Hamilton]

kdb+ does support a form of views. You use double colon :: to assign a view of a table to a variable. The result then becomes cached in that variable and is only updated as necessary when the underlying table changes.

e.g.

`q)t:([] a:til 1000000)
q)select from t where a in 1 1000 2000
a
—-
1
1000
2000`

Create the view

`
q)myView::select from t where a in 1 1000 2000
q)myView
a
—-
1
1000
2000`

Notice time to query cached view is 0

`
q)\t do[100; select from t where a in 1 1000 2000]
377
q)\t do[100; myView]
0`

insert new value, next query costs a little

 

q)`t insert ([] a:999999 2000)
1000000 1000001
q)\t do[100; myView]
5

updated data shown

`
q)myView
a
—-
1
1000
2000
2000`

system “b” or \b will display the views that exist within your kdb+ process.

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