Requests are sent by an application to Teradata Database to initiate an action. Responses are sent by Teradata Database to the application to reflect the results of that action. Both requests and responses are associated with an established session. One or more Teradata SQL statements that are submitted to Teradata Database at the same time are called a Teradata SQL request. Having several statements in the same request saves message transfer time, a factor of interest to CPU‑bound and I/O‑bound programs or sites, since, for example, a two-statement multi‑statement request uses half the CPU time of two single statement requests.
Most requests contain all of the data needed for their completion, but a few require additional data. For example, requests that insert a large database field, such as a picture or a program that runs within the database, first prompt CLIv2 to supply the data or program. The application then continues the request by providing the data or program.