Amazon Redshift is a fully managed, petabyte-scale data warehouse service that is optimized for large-scale data set storage and complex queries. It uses columnar storage, which can improve query performance by reducing the amount of data that needs to be read from disk. To optimize for complex queries, you can configure Redshift to use massively parallel processing (MPP) architecture, which distributes the data and query processing across multiple nodes in a cluster. This can improve query performance and reduce query execution time. Amazon RDS with read replicas can improve read performance, but it is not designed for complex queries. Amazon DynamoDB with global secondary indexes can be used to support complex queries, but it is a NoSQL database service and may not be suitable for large-scale data warehousing. Amazon Athena can be used for querying data stored in Amazon S3, but it is not a data warehouse service and may not be optimized for complex queries.