Incremental Load

[#1]

Hi to all,

                I am just try to do incremental reload....actually i just stored my old data in QVD then am trying to reload my new data and Concatenate to my old QVD into my new data...but my old data and new data everthing will be in same place only and i cant reload using max of date because in my new excel old data will be updated so how can i update my new excel file into the old one..please its urgent...thanks in advance to all

[#2]

hi ,

this is field of your table.

send a set of  sample data in excel.

Regards

Vimlesh

[#3]

Data is not important i have attached the snap shot of my excel structure....so kindly create like that....

[shambhub]

Hi,

Without providing table structure or list of columns it will be difficult to provide solution.

[#5]

here is the data Structure....only 4 columns is enough....in the before discussion itself i have mentioned clearly with this image...what i want to get.....Thanks in adavnce

[qepmalheiros]

Using QVD Files for Incremental Load

Incremental load is a very common task in relation to data bases. It is defined as loading nothing but new or changed records from the database. All other data should already be available, in one way or another. With QVD Files it is possible to perform incremental load in most cases.

The basic process is described below:

1. Load the new data from Database table (a slow process, but loading a limited number of records).

2. Load the old data from QVD file (loading many records, but a much faster process).

3. Create a new QVD file.

4. Repeat the procedure for every table loaded.

The complexity of the actual solution depends on the nature of the source database, but the following basic cases can be identified:

1) Case 1: Append Only (typically log files

2) Case 2: Insert Only (No Update or Delete)

3) Case 3: Insert and Update (No Delete)

4) Case 4: Insert, Update and Delete

Below you will find outlined solutions for each of these cases. The reading of QVD files can be done in either optimized mode or standard mode. (The method employed is automatically selected by the QlikView script engine depending on the complexity of the operation.) Optimized mode is (very approximately) about 10x faster than standard mode or about 100x faster than loading the database in the ordinary fashion.

Case 1: Append Only

The simplest case is the one of log files; files in which records are only appended and never deleted. The following conditions apply:

• The database must be a log file (or some other file in which records are appended and not inserted or deleted) which is contained in a text file (no ODBC/OLE DB).
• QlikView keeps track of the number of records that have been previously read and loads only records added at the end of the file.

Script Example:Buffer (Incremental) Load * From LogFile.txt (ansi, txt, delimiter is '\t', embedded labels);

Case 2: Insert Only (No Update or Delete)

If the data resides in a database other than a simple log file the case 1 approach will not work. However, the problem can still be solved with minimum amount of extra work. The following conditions apply:

• The data source can be any database.
• QlikView loads records inserted in the database after the last script execution.
• A field ModificationDate (or similar) is required for QlikView to recognize which records are new.

Script Example:QV_Table:SQL SELECT PrimaryKey, X, Y FROM DB_TABLEWHERE ModificationTime >= #$(LastExecTime)#AND ModificationTime < #$(BeginningThisExecTime)#; Concatenate LOAD PrimaryKey, X, Y FROM File.QVD;STORE QV_Table INTO File.QVD;(The hash signs in the SQL WHERE clause define the beginning and end of a date. Check your database manual for the correct date syntax for your database.)

Case 3: Insert and Update (No Delete)

The next case is applicable when data in previously loaded records may have changed between script executions. The following conditions apply:

• The data source can be any database.
• QlikView loads records inserted into the database or updated in the database after the last script execution
• A field ModificationDate (or similar) is required for QlikView to recognize which records are new.
• A primary key field is required for QlikView to sort out updated records from the QVD file.
• This solution will force the reading of the QVD file to standard mode (rather than optimized), which is still considerably faster than loading the entire database.

Script Example:QV_Table:SQL SELECT PrimaryKey, X, Y FROM DB_TABLEWHERE ModificationTime >= #$(LastExecTime)#; Concatenate LOAD PrimaryKey, X, Y FROM File.QVDWHERE NOT Exists(PrimaryKey); STORE QV_Table INTO File.QVD;

Case 4: Insert, Update and Delete

The most difficult case to handle is when records are actually deleted from the source database between script executions. The following conditions apply:

• The data source can be any database.
• QlikView loads records inserted into the database or updated in the database after the last script execution.
• QlikView removes records deleted from the database after the last script execution.
• A field ModificationDate (or similar) is required for QlikView to recognize which records are new.
• A primary key field is required for QlikView to sort out updated records from the QVD file.
• This solution will force the reading of the QVD file to standard mode (rather than optimized), which is still considerably faster than loading the entire database.

Script Example:

Let ThisExecTime = Now( );

QV_Table:

SQL SELECT PrimaryKey, X, Y FROM DB_TABLE

WHERE ModificationTime >= #$(LastExecTime)#

AND ModificationTime < #$(ThisExecTime)#;

Concatenate LOAD PrimaryKey, X, Y FROM File.QVD

WHERE NOT EXISTS(PrimaryKey);

Inner Join SQL SELECT PrimaryKey FROM DB_TABLE;

If ScriptErrorCount = 0 then

STORE QV_Table INTO File.QVD;

Let LastExecTime = ThisExecTime;

End If

QlikView 11.20 SR6