Unlock a world of possibilities! Login now and discover the exclusive benefits awaiting you.
What is the difference between preceding load & resident load.
when we have to used preceding load?
Thank you.
------------------------------------------------------Preceding load ----------------------------------------------------------
1. The preceding load can be used to define multiple calculations and transformations within on e load script2 The 2.preceding load takes input from a previous load statement
3. Preceding load is invoked by checking “Preceding load” while selecting load statement
4. Using a preceding load you don’t need to perform the same calculation in several times5. We can do aggregations and calculations using Preceding load
Preceding Load Sample Script:
Preseding_Sample:
load
OfficeCountry,sum(Amount) as Amt
group by OfficeCountry;
Office_Loc:
Directory;
LOAD Office,
OfficeAddress,
OfficePostalCode,
OfficeCity,
OfficeStateProvince,
OfficePhone,
OfficeFax,
OfficeCountry,
Amount
FROM
SampleData.txt
(txt, codepage is 1252, embedded labels, delimiter is '\t', msq);
------------------------------------------------------Resident load ---------------------------------------------------------
Sample Script for reference
Country_population:
LOAD Country,
Capital,
[Area(km.sq)],
[Population(mio)],
[Pop. Growth],
Currency,
Inflation,
[Official name of Country]
FROM
[Preceding Load\Country_population.csv]
(txt, codepage is 1252, embedded labels, delimiter is ',', msq);
calculated_Table:
load
Country,
sum([Population(mio)])/1565 as percentage_Population
resident Country_population group by Country;
drop table Country_population;
Simple :Creating # Temp table in sqlserver in temporary basis and at the end after calculation drop the # Temp
Excellent Blog
Hi,
Generally, preceding load is a simplified function that loads faster than resident load, this is done by having the same calculation for many places.
Do have a look at this detailed document posted by Henric Crostrom:
Let me know if this helps!
Regards,
Gaston
In most cases, the same result can be achieved by using a preceding LOAD instead, that is, a LOAD statement that loads from the LOAD or SELECT statement below, without specifying a source qualifier such as From or Resident that you would normally do. A preceding LOAD is generally the faster option, but there are some cases where you need to use a ResidentLOAD instead:
IS THIS RIGHT?
Hi Prachi,
The following examples you mentioned are right, in those cases you have to use resident.
But this whole post is a bit outdated, Since the new versions of Qlik (last couple of years), preceding load is SLOWER than RESIDENT.
Please check Rob's post from a year ago to further understand the issue
http://qlikviewcookbook.com/2016/04/the-cost-of-preceding-load/
BR,
Eliran.
Hi
Please go through this well explained with example
Resident Load:
In some cases we need to reload the same table more than once in a single script execution to
reprocess the same data after the first read in order to make it adequate for our data model. Since the
data is being stored in RAM after each query during the script execution, we can use that RAM-stored
data instead of going directly to the original data source. This is accomplished via a Resident Load.
Resident keyword is used to reference the data in RAM model, that is, all the tables that have
been previously read in the preceding queries of the same script.
Example:
Orders:
SELECT
OrderID,
Customer,
Sales
FROM Orders;
CustomerFirstInvoiceDate: // Reloading the Orders table with Group By to get the first invoice date
LOAD
Customer,
Min(Date) AS CustomerStartDate
RESIDENT Orders
GROUP BY Customer;
Precedent Load:
The preceding LOAD feature allows you to load a table in one pass, but still define several
successive transformations. Basically, it is a LOAD statement that loads from the LOAD or SELECT
statement below, without specifying a source qualifier such as From or Resident that you would
normally do.
You can stack any number of LOAD statements this way. The statement at the bottom will be
evaluated first, then the statement above, and so on until the top statement has been evaluated. You
can achieve the same result using Resident, but in most cases a preceding LOAD will be faster.
Another advantage of preceding load is that you can keep a calculation in one place, and reuse it in LOAD statements placed above.
Example 1: Transforming data loaded by a SELECT statement
If you load data from a database using a SELECT statement, you cannot use Qlikview functions to
interpret data in the SELECT statement. The solution is to add a LOAD statement, where you perform
data transformation, above the SELECT statement.
In this example we interpret a date stored as a string using the Qlikview function Date# in a
LOAD statement, using the previous SELECT statement as source.
Orders:
LOAD *,
Date(Date#(OrderDate, ’YYYYMMDD’), ‘MM/DD/YYYY’) as OrderDate;
SQL SELECT OrderID
OrderDate ,
Amount
FROM Orders;
Example 2: Simplifying your script by reusing calculations
In this example we use a calculation more than once in the script
Data:
LOAD *,
Age( FromDate + IterNo() – 1, BirthDate ) as Age,
Date( FromDate + IterNo() – 1 ) as ReferenceDate
Resident Policies
While IterNo() <= ToDate - FromDate + 1 ;
By introducing the calculation in a first pass, we can reuse it in the Age function in a preceding
load
Data:
LOAD ...,
ReferenceDate,
Age( ReferenceDate, BirthDate ) as Age;
LOAD *,
Date( FromDate + IterNo() – 1 ) as ReferenceDate
Resident Policies
While IterNo() <= ToDate - FromDate + 1 ;
guys i am getting confused.
Resident Load:
It allows you to create a new logical table using qlikview based on existing table (which loaded in memory)
Syntax
TabeA:
Load ...
From ....;
[New Table]:
Load
....
Resident TabeA;
Preceding Load:
Its contains more than one load statements that execute from the Bottom up.
--> It allows you to created additional ETL transfermation using transformed field from the previous load statements.
let say, Calculate margin using two fields from the previous load statement: sales and LandedCost
example,
Fact:
Load *,
((Sales-LandedCost)/Sales) as Margin; // preceding load using previous load statement field
Load * Inline
Product,Sales,LandedCost
A,210,100
B,310,150
C,500,400
];
Hope this helps you
Regards,
Deva