topic Re: Precedent Load vs Resident Load in QlikView

Precedent Load vs Resident Load

Wed, 05 Dec 2012 21:08:48 GMT

Hi Folks, I am trying to create one intermediate QVD and first I tried with Precedent Load:

FINAL_QVD:

LOAD *,

SubField(A,'.',1) as X,

SubField(A,'.',2) as Y,

ApplyMap('MAP_T',AutoNumber(LEFT(A,LEN(A)-3)),'No') as FLAG

;

LOAD DISTINCT A,B,C,D FROM [$(vQVDpath\TEST_CHECK.qvd)] (qvd);

The TEST_CHECK.qvd have 4M rows

For this code I got 4M rows in FINAL_QVD table also. But I am expecting only 1M ditinct rows only.

Again, I re-write my script with Resiednt Load below:

LOAD DISTINCT A,B,C,D FROM [$(vQVDpath\TEST_CHECK.qvd)] (qvd);

FINAL_QVD:

NOCONCATNATE

LOAD *,

SubField(A,'.',1) as X,

SubField(A,'.',2) as Y,

ApplyMap('MAP_T',AutoNumber(LEFT(A,LEN(A)-3)),'No') as FLAG

RESIDENT T;

DROP TABLE T;

With this, I got 1M rows in my new table FINAL_QVD.

I wonder, what is wrong with precedent load

What is the difference b/n Precedent Load & Resident Load

Thanks,

Siri

Re: Precedent Load vs Resident Load

whiteline — Thu, 06 Dec 2012 06:27:18 GMT

Hi.

Distinct statement is not working this way with Precedent LOAD.

Re: Precedent Load vs Resident Load

hic — Thu, 06 Dec 2012 11:13:11 GMT

Put the distinct clause in the top load statement, and the preceding load will remove the duplicates. A distinct clause in the following load statements will be disregarded.

HIC

Re: Precedent Load vs Resident Load

Thu, 06 Dec 2012 16:26:51 GMT

Thanks for Reply HIC....

I wondor, Which load give better performance?

Re: Precedent Load vs Resident Load

perumal_41 — Fri, 07 Dec 2012 04:57:08 GMT

Hi,

use Preceding Load ,this one better performance,but resident Load slow script and slow ur performance

Regards

Perumal A

Re: Precedent Load vs Resident Load

whiteline — Fri, 07 Dec 2012 07:44:20 GMT

Hi.

I think you should make some tests, because it depends.

Just have made some tests with mapping and 6M rows. In my case "optimized QVD load+mapping from Resident" is faster than "loading from QVD and mapping with preceding load".

I guess it's because using preceding load here turns off optimized qvd load.