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Showing posts from May, 2014

Email Alerts are not received...

In one of application, Email alerts are sent using SQL sp_send_dbmail stored procedure. Email alerts were working properly, but suddenly noticed email alerts are not received.

To troubleshoot the issue, first I checked the msdb.dbo.sysmail_event_log table using the below query.

SELECT log_id, event_type, log_date, description, process_id, mailitem_id, account_id, last_mod_date, last_mod_user
log_date DESC

If there is any error, you should see records with the event_type value as error.
In my case there are records with event_type value as error, and the description value for those records is same as below

The mail could not be sent to the recipients because of the mail server failure. (Sending Mail using Account 3 (2018-02-01T10:41:27). Exception Message: Cannot send mails to mail server. (The SMTP server requires a secure connection or the client was not authenticated. The server response was: Authentication required).  )

As per the error descript…

Importance of the Surrogate Key in Data Warehouse Design

In Data Warehousing, Surrogate Key is a unique identification key in a dimension table which is independent from the source.
Normally it is an auto increment integer value.

The purpose to have a surrogate key in a dimension table is to makes the relationship between dimension tables and fact tables independent from the source.
Below example will explain the importance of the surrogate key clearly.

Let's say in a company they maintains the employee code as a fixed digit number and assume the number of digit is 4.
After few years, the company is growing and the number of employees get increased.
Due to that 4 digit employee code will not be sufficient and they decided to makes the number of digits in the employee code to 6.
In such scenario, employee code of the every employee will get changed.

But in the data warehouse, if we use the employee code as the key without using any surrogate key, then the employee is linked with facts using employee code.
Therefore if the employee code …