Re: Do function calls the cached?

[Daniel Caldeweyher <dcalde@xxxxxxxxx>]

Thanks David,

Lateral did the trick:

CREATE VIEW with_keywords AS

SELECT x,y,z, keywords.a, keywords.b, keywords.c

FROM large_table l, LATERAL extract_keywords(l.*) keywords(a,b,c)

Regards,

Daniel

On Wed, Aug 31, 2016 at 6:46 AM, David G. Johnston <david.g.johnston@xxxxxxxxx> wrote:

On Tue, Aug 30, 2016 at 4:15 PM, Daniel Caldeweyher <dcalde@xxxxxxxxx> wrote:

select x,y,z, (extract_keywords(l.*)).*

​[...]​

 

Does this mean the function gets called three time?

​Yes.

​

 

(​function_call(...)).*​

 

​syntax is problematic.  You should avoid it via one of two options.

LATERAL (new way, preferred)

or

CTE​ (old way)

In the CTE version you make the call in the CTE but do "(col).*" in the main query.  This way the function is only called once to generate a composite output, then the composite output is exploded.

With LATERAL the system is smart enough to do it the right way.

David J.