what is broadlog id primary sequenec

Hello @shruti1,

primary key is unique record identifier and primary key sequence is function how that key is generated. Take a look at following atricle:

https://experienceleague.adobe.com/docs/campaign-classic/using/configuring-campaign-classic/schema-reference/database-mapping.html?lang=en#management-of-keys

You can create your own or use ones adobe campaign has already added. 

Definition:
In SQL, a sequence is a database object that generates a sequence of numeric values. It is often used to generate unique identifiers for rows in a table. Sequences are typically used to provide a unique number for primary keys or other columns that require unique values.

In adobe campaign when you reach the end of the sequence the sequence reset from the begining. When this happens usually we set update the sequence to start from negative number.
https://experienceleague.adobe.com/docs/campaign-classic/using/monitoring-campaign-classic/database-maintenance/application-objects.html?lang=en

Marcel Szimonsiz