![]() ![]() At times, depending on the volume of data, building this intermediate result set requires scanning through hundreds of millions of rows from multiple tables, which can be both time- and resource-consuming. ![]() After sending the top 10 expensive orders from the sorted intermediate result set to client, it is discarded. This sorting is called an intermediate result set. For example, fetching the top 10 most expensive orders requires a pre-computed sort on the price value of each order in descending order. Intermediate results are a temporary dataset required by a SQL operation to compute the actual end result. PostgreSQL uses a temporary work area for several operations, including to hold intermediate results to build indexes, and sort or group records for queries. For more information, refer to Multi-AZ DB cluster deployments.ĭatabase systems like PostgreSQL try to perform operations in memory for optimal performance, but there are situations where they must use a temporary work area on disk. These instances are equipped with fast NVMe SSDs for local storage, ideal for high speed and low-latency storage. The optimization of transaction latency uses local storage on purpose-built Amazon Elastic Compute Cloud (Amazon EC2) instances. This deployment option increases read capacity with two readable standby instances, and improves write transaction latency and failover times. In March 2022, we introduced a new Multi-AZ deployment option for Amazon Relational Database Service (Amazon RDS) for PostgreSQL, called Multi-AZ DB clusters. ![]()
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