what are optimized loads and unoptimized loads ?

[nikhilgarg]

Hello,

Can anyone help me out by telling what are optimized loads and unoptimized loads ?

Thanks

[Siva_Sankar · Accepted solution]

QVD files can be read in two modes: standard (fast) and optimized (faster). The selected mode is determined automatically by the QlikView script engine. Optimized mode can be utilized only when all loaded fields are read without any transformations (formulas acting upon the fields), though the renaming of fields is allowed. A WHERE clause causing QlikView to unpack the records will also disable the optimized load.

1)F1 as NewField  -  Renaming allowed, so it is optimized load

Ex:

LOAD

Field1 AS Date,

Field2 AS Sales

FROM DataSource;

2)F1 * 2 as NewField – Transformation is not allowed, so it is non optimized load

Ex:

LOAD

Field1 AS Date,

Field2 AS Sales,

Discount,

Field2 - Discount AS NetSales   // This is a transformation

FROM DataSource;

3)1 as NewField – Cannot add a new field, so it is non optimized load

LOAD

Field1 AS Date,

Field2 AS Sales,

1 AS Flag   // Adding new field

FROM DataSource;

4)WHERE Exists(F1) –  We can use Single Field in Exists(), so it is an Optimized load

LOAD

Field1 AS Date,

Field2 AS Sales

FROM DataSource

WHERE Exists(Field1);

5)where exists(F1, Some Transformation) – We cannot use Multiple Field in Exists(), so it is a non Optimized load

LOAD

FirstName,

LastName,

Sales

FROM DataSource

WHERE Exists(Field1, FirstName& ' ' &LastName);

[Siva_Sankar]

Also, refer here Turning Unoptimized Loads into Optimized Loads

[Siva_Sankar]

In simple words,

Optimized loads are faster and preferable for large data.

The term optimized load means, if no calculations are made during loading and no filters in a WHERE CLAUSE.

The only possible filter condition is: WHERE Exists(Field)

Optimized Load:

Load * From Table

WHERE EXISTS(Department);

Unoptimized Load:

Load * From Table

WHERE Department = 'SALES'

[nikhilgarg]

Thanks shankarece,

It helped me. So, by your reply, i assume that if no transformations applied while loading the datafrom QVD, then it will be an optimized load else unoptimized load.

[Siva_Sankar]

Yes Nikhil,

Except renaming and WHERE Exists(onefield) is allowed in optimized load.

[PanguiCat]

A trick i have been using is to load QVD without transformation as tem table then i load table with transformations i need with Resident.