J% Ports

The biggest port, and the one that matters most: RUBiS is a research benchmark that other people wrote and that a lot of middleware papers measure themselves against, so its SQL was not arranged to make anything convenient. Every servlet builds its queries inline as strings — a bid, a comment, a category listing, the four separate updates an item can need — and each one became an external type sitting beside the servlet that uses it. It is also the port that shows the conversion scaling past a handful of queries: most of the servlets change by a few lines each, and the queries themselves are copied across unchanged.

A small internal application, and a good test precisely because nobody wrote it carefully. Its queries select and delete uploaded submissions by four different combinations of date, student and project, so the same table is addressed a dozen slightly different ways — the shape real code takes when it grows a query at a time. One of its columns is named group, which is a reserved word in SQL; the port keeps the statement exactly as it was written, and it compiles.

The clearest illustration of how little a port has to disturb. jcrontab is the largest application here by file count and all of its SQL is in one class, the data-access layer for the events table, so a single file changes and every other one is untouched — the scheduler itself never learns that its queries stopped being strings.

The smallest complete application, and the one whose queries carry the most parameters: a contact has eleven fields, so its insert binds eleven values and its update binds twelve — those fields plus the row's id, and the widest statement in the corpus. That makes it the case where writing the parameters out as named, typed holes earns the most, since the PreparedStatement it replaces leaves twelve anonymous question marks to be filled in the right order.

The only port that uses both modules, which makes it the one worth reading first. sdriver strips a query down to its shape and compares that signature against a stored one, so it holds regular expressions as well as SQL — patterns for comments, quoted strings, numbers and punctuation. In the port each Pattern.compile("…") becomes a type: new TriviaRegex() instead of Pattern.compile("\\+|-|\\."). A pattern that will not compile now stops the build rather than throwing the first time the driver is asked to inspect a query.

Checking a query costs build time, and how much depends on how hard you ask the compiler to look. This is the measurement: the same statement — select * from customer — compiled four ways, as plain syntax, against a schema file, against a live database connection, and with the SQL-security checks on. It is here because the honest version of "the compiler checks your queries" includes what that checking costs.