Guilherme <gbmpere...@gmail.com> wrote: > Well, I thought that if the execution followed a plan.. I could get for > example, the cardinality from the results until a point, say a join.
I don't see how the conclusion follows from the premise. Why does "follows execution plan" have to imply "provides ready access to the data I happen to want"? > Imagine a query with 15 joins.. the execution would make a join What exactly does "make a join" mean? A join is a declarative construct - it specifies *what* data you want, not *how* to procur it. The query engine then does whatever it deems necessary to produce the data you've described with a join. > than, with > the results from this join, make another join with results form other > joins.. and so on.. That's not how database engines normally work. They don't explicitly produce intermediate resultsets. Imagine that you have a phonebook, sorted by last name, first name. Suppose you want to find all people named John Smith. Would you first write down all Smiths, then go through that intermediate list looking for Johns? Or would you check for the first name as you go through the Smiths in the phonebook? > I could get the cardinalities before the joins You are engaging in wishful thinking. -- Igor Tandetnik _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
