Sunday, August 27, 2006

Questions from the Wicket world

Here are some answers to questions that came up on the Wicket user list, about using Shades with the Wicket "library example"

1) how to do concise queries:

Usually the query is defined in the ORMDictionary. In
the example I showed, I defined the query on-the-fly.
Most of the time you would just grab a query from the
dicitonary. So it's this concise:

dbSess.setParameter("author", "william gibson");
dbSess.executeQuery(conn, dict.getQuery("q-by-auth"))

2) how to do arbitrarily complex joins:

There is no limit on how deep or complex the joins can
be with Shades. Here is an example where we setup a
query to find all books published by whatever
publisher publishes the works of William Gibson.
(again bear in mind that usually we would just grab
this query from the dictionary, I am only defining it
inline to be illustrative).

aBook.where("AUTHOR like 'william gibson');
anotherBook.relatedTo(aPublisher, "book<->publisher");
dbSess.excecuteQuery(conn, q);

3) performance

Ahhh, I am especially stoked on this. Shades uses
batch updates and the other tricks common to ORM's. I
learned most of these tricks doing JDOMax. I think the
biggest reason shades has good performance is because
the codebase is so tight. When it comes to defining
queries on the fly, shades will be better than any
language that compiles a query (for example JDOQL),
because Shades bypasses the parse phase, and the
translation of the AST from JDOQL to SQL. Shades does
query caching like any other ORM.

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