View v/s Materialized View in SQL

1) First difference between View and materialized view is that, In Views query result is not stored in the disk or database but Materialized view allow to store query result in disk or table.

2) Another difference between View vs materialized view is that, when we create view using any table, rowid of view is same as original table but in case of Materialized view rowid is different.

3) One more difference between View and materialized view in database is that, In case of View we always get latest data but in case of Materialized view we need to refresh the view for getting latest data.

4) Performance of View is less than Materialized view.

5)View vs Materialized View is that, In case of Materialized view we need extra trigger or some automatic method so that we can keep materialized view refreshed, this is not required for views in database.

When do we go for Materialized View?

View is logical view of the table, with no data stored on the disk.It will return the latest data upon queried.
The performance of the view is dependant on how efficiently the query is framed upon.If the query has many joins and joins based on non indexed columns then the performance will be poor.

Materialized views is logical view of data. The queried result set is stored in the form of a table. So the next time the optimizer fetches the result from materialized view rather than querying the tables,this can greatly speed up the response time of end user application.

Hope this articles helps you in understanding the concepts of view & materialized view

Comments

Comparing Objects in Informatica

We might face a scenario where there may be difference between PRODUCTION v/s SIT version of code or any environment or between different folders in same environment. In here we go for comparison of objects we can compare between mappings,sessions,workflows In Designer it would be present under "Mappings" tab we can find "Compare" option. In workflow manger under "Tasks & Workfows" tab we can find "Compare" option for tasks and workflows comparison respectively. However the easiest and probably the best practice would be by doing using Repository Manager.In Repository Manager under "Edit" tab we can find "Compare" option. The advantage of using Repository manager it compares all the objects at one go i.e. workflow,session and mapping. Hence reducing the effort of individually checking the mapping and session separately. Once we select the folder and corresponding workflow we Can click compare for checking out ...

Target Load Type - Normal or Bulk in Session Properties

We can see the Target load type ( Normal or Bulk) property in session under Mapping tab and we will go for Bulk to improve the performance of session to load large amount of data. SQL loader utility will be used for Bulk load and it will not create any database logs(redolog and undolog), it directly writes to data file.Transaction can not be rolled back as we don't have database logs.However,Bulk loading is very as compared to Normal loading. In target if you are using Primary Key or Primary Index or any constraints you can't use Bulk mode. We can see this property in the below snap shot.

SCD Type 2 Implementation in Informatica using dynamic lookup

We have already covered how a dynamic look up works the same can be found out from the following link http://dwbuddy.blogspot.com/2014/06/dynamic-look-up-in-informatica.html So let's see how we can use it in a regular SCD type 2 mapping. The logic used in SCD type 2 is same as discussed in earlier blog i.e. http://dwbuddy.blogspot.com/2015/01/scd-type-ii-implementation-in.html . The only difference being here is we have used dynamic look up instead of a static one. We go for dynamic look up when there are duplicate entries for a PK value and only the latest record present in the file should be termed as active. Let us consider the following sample data So for EMP_ID 101 we have two records in the same day flow so the latest record i.e. with salary as 1500 should be termed as Active record. The mapping will look in the following way So in here we have a dynamic lookup couple of expression transformations,a transaction control transformation which is use...

IT Pandora (ETL,DB,UNIX,AWS,NodeJS,Github etc.)

Search This Blog