Why are there varying degrees of flexibility in the rules regarding the implementation of the queries as opposed to the update functions?
This is again a consequence of the environment being modeled. It is assumed that ad hoc queries are submitted by less sophisticated end users, probably using a front-end SQL query tool. The query tool generates fixed SQL text, and the users are assumed not to edit or modify the text before it is sent to the server. These assumptions motivate the SQL-as-written rules for queries in the benchmark. In contrast, very few restrictions are placed on the implementation of the two update functions. It is assumed that these are implemented by “experts” and submitted by a very small group of sophisticated users or DBAs. The implementors of the updates are very familiar with the system at hand and can be expected to implement the updates for optimal performance. This may include using a pre-compiled program with embedded SQL statements, sorting the rows to be inserted or deleted in a particular order, or splitting the work of a given update function up among multiple processes.
