Partial reload executes a specific part of sciprt, this can for example be used to refresh a certain table.
Incredemental reload is defined in the script to update certain tables incredementally, for example to add only new transactions to a transaction table.
Incremental reload is especially used to decrease the reload time, by for instance only loading new records from a data source instead of the complete table.
Incremental load is a common task in relation to data bases. purpose of incremental load is, To Extract only the new or modified transactions from the source table and append those records to the ones previously saved in the Base QVD's. The approach of incremental load depends upon the nature of the source database, meaning
IF you want to use the data from a logfile which is contained in a textfile, you can use the append only,no need to connect to ODBC OR OLE DB, QV keeps track of the number of records that have been previously read and loads only added at the end of the files.
If the data resides in a database other than a logfile you can use insert, update and delete(I,U &D)
The conditions apply for I,U and D
a. The data source can be any database
b.QV loads records inserted into the database or update in the database after the last script execution.
c. QV removes records deleted from the database after the last script execution.
d.A field ModificationDate is required to recognize which records are new.
e. Primary key field is required to sort out updated records from the QVDfiles.
The reading of QVD file will be forced to standard mode rathan than super-fast mode but still it is faster than loading the entire database.
In many business environments, there will be many large transaction tables. These tables may receive 1000’s or millions of rows of data daily or monthly. Since the data is huge and it may be sensitive also from the history standpoint, you may not want to delete the existing records, instead you will load only if the data is new. In such scenarios incremental load is used.
