1. A method of operating a data access and query optimizer (DAQO) circuitry configured to generate a query plan for accessing a database, the method comprising: receiving, at the DAQO circuitry, at least two electronic queries from a database client; determining, by the DAQO circuitry, whether the received at least two queries form a part of a set of ordered queries comprising a repeating sequence of a plurality of queries, by determining whether the received at least two queries match a part of the sequence of queries; determining, by the DAQO circuitry, a Quality of Service measure specifying a Quality of Service that the database client requires to be achieved during execution of the at least two electronic queries; when the received at least two queries are determined to form the part of the set of ordered queries, selecting, by the DAQO circuitry, a query plan for executing queries in the sequence that match the received at least two queries and a query that is subsequent to the matched queries in the sequence; and executing, by the DAQO circuitry, the query that is subsequent to the matched queries in the sequence prior to receiving that query from the database client, wherein the query plan is selected from a plurality of stored query plans associated with the received at least two queries, wherein the process of selecting the query plan comprises: comparing, by the DAQO circuitry, the determined Quality of Service measure with a respective Quality of Service figure associated with each of the plurality of stored query plans; and selecting, by the DAQO circuitry, the query plan from among the plurality of stored query plans whose Quality of Service figure best matches the determined Quality of Service measure based on results of the comparison, and wherein the DAQO circuitry is implemented in hardware or in a combination of hardware and software.