A company uses Amazon Redshift for its enterprise data warehouse. A new op-premises PostgreSQL OLTP DB must be integrated into the data warehouse. Each table in the PostgreSQL DB has an indexed last_modified timestamp column. The data warehouse has a staging layer to load source data into the data warehouse environment for further processing.
The data log between the source PostgreSQL DB and the Amazon Redshift staging layer should NOT exceed four hours.
What is the most efficient technique to meet these requirements?
A . Create a DBLINK on the source DB to connect to Amazon Redshift. Use a PostgreSQL trigger on the source table to capture the new insert/update/delete event and execute the event on the Amazon Redshift staging table.
B . Use a PostgreSQL trigger on the source table to capture the new insert/update/delete event and write it to Amazon Kinesis Streams. Use a KCL application to execute the event on the Amazon Redshift staging table.
C . Extract the incremental changes periodically using a SQL query. Upload the changes to multiple Amazon Simple Storage Service (S3) objects and run the COPY command to load the Amazon Redshift staging table.
D . Extract the incremental changes periodically using a SQL query. Upload the changes to a single Amazon Simple Storage Service (S3) object run the COPY command to load to the Amazon Redshift staging layer.
Answer: C