ETL (Extract, transform, load) Question: Download Questions PDF
Explain What are snapshots? What are materialized views & where do we use them? What is a materialized view log?
Answer:
Snapshots are read-only copies of a master table located on a remote node which is periodically refreshed to reflect changes made to the master table. Snapshots are mirror or replicas of tables.
Views are built using the columns from one or more tables. The Single Table View can be updated but the view with multi table cannot be updated.
A View can be updated/deleted/inserted if it has only one base table if the view is based on columns from one or more tables then insert, update and delete is not possible.
Materialized view
A pre-computed table comprising aggregated or joined data from fact and possibly dimension tables. Also known as a summary or aggregate table.
Views are built using the columns from one or more tables. The Single Table View can be updated but the view with multi table cannot be updated.
A View can be updated/deleted/inserted if it has only one base table if the view is based on columns from one or more tables then insert, update and delete is not possible.
Materialized view
A pre-computed table comprising aggregated or joined data from fact and possibly dimension tables. Also known as a summary or aggregate table.
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