- 1) Optimized and unoptimized QVD Load Situations?
- Ans. When concatenating two tables that don't have the same number of fields, if the second table has the same fields than the first one and then some extra fields the load will still be optimized, if done the other way around it will not be optimized.
- e.g. All Loads are optimized
Table:
LOAD // Optimized
A,
B,
C
FROM Table1.qvd (qvd);
CONCATENATE(Table) // Optimized
LOAD
A,
B,
C,
D,
E
FROM Table2.qvd (qvd);
- e.g. 2nd Load isn't optimized
Table:
LOAD // Optimized
A,
B,
C,
D,
E
FROM Table2.qvd (qvd);
CONCATENATE(Table) // Not optimized
LOAD
A,
B,
C
FROM Table1.qvd (qvd);
Or 2nd Ans. Is
Optimized load is much faster and therefore preferable, especially for larger data sets.
Optimized loads are possible if no transformations (calculations) are made during the load, and no (almost) filtering is done in a WHERE clause.
The only acceptable filter is using function Exists:
WHERE Exists(Field)
So for example this load can't be optimized:
Load * From ... WHERE Country = 'US'
but this load can:
Load * From ... WHERE EXISTS(Country)
================================
On the other hand, the only time you want the load not to be optimized, is if you load a Mapping table from a QVD file. In this case, Optimized load doesn't quite work, so you want to make the load non-optimized deliberately.
Another Answer For Optimize and Non- Optimized
Optimized load is much faster and therefore preferable, especially for larger data sets.
Optimized loads are possible if no transformations (calculations) are made during the load, and no (almost) filtering is done in a WHERE clause.
The only acceptable filter is using function Exists:
WHERE Exists(Field)
So for example this load can't be optimized:
Load * From ... WHERE Country = 'US'
but this load can:
Load * From ... WHERE EXISTS(Country)
================================
On the other hand, the only time you want the load not to be optimized, is if you load a Mapping table from a QVD file. In this case, Optimized load doesn't quite work, so you want to make the load non-optimized deliberately.
see the attached pdf also
For different types of load go to this link
Different ways to load data in to Qlikview
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