IvanDrago wrote:
yes what does the optimized do in qlikview terms? still not sure<div></div>
I'm not sure I understand the question, but I'll try to expand on what Gordon said.
An optimized load ONLY happens on QVD files. Under certain circumstances, QlikView is able to read the needed portion of the file directly into memory without actually processing it row by row. As Gordon says, this can be MUCH faster than an unoptomized load of the same QVD. For that matter, this can even be much faster than a RESIDENT load from an existing table.
The trick to making your loads optimized is to recognize what you can and can't do. You don't have to read ALL the fields, and you can rename the fields, but you can't add any new fields, or perform any logic on the fields. The ONLY condition you can have in your WHERE statement is a single exists().
As Gordon says, the optimized load is often so much faster than an unoptimized load that it's usually worth loading that way, and only AFTER the data is in memory do you perform other manipulations on it.
For example, instead of this:
[My Table]:
LOAD // unoptimized QVD load
ID
,Status
,Cust as Customer
,if(Status='Active','Y','N') as Active?
FROM MyTable.qvd (QVD)
WHERE match(Status,'Active','On Hold')
AND wildmatch(Customer,'*Bob*','ABC *')
;
Do this:
[My Table]:
LOAD * INLINE [
Status
Active
On Hold
];
INNER JOIN ([My Table])
LOAD // optimized QVD load
ID
,Status
,Cust as Customer
FROM MyTable.qvd (QVD)
WHERE exists(Status)
;
INNER JOIN ([My Table])
LOAD
ID
,if(Status='Active','Y','N') as Active?
RESIDENT [My Table]
WHERE wildmatch(Customer,'*Bob*','ABC *')
;
