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* Part 1: define ValueTypeSet. We're going to use this instead of `HashSet<ValueType>` so that we can clearly express the empty set and the set of all types, and also to encapsulate a switch to `EnumSet`." * Part 2: use ValueTypeSet. * Part 3: fix type expansion. * Part 4: add a test for type extraction from nested `or`. * Review comments. * Review comments: simplify ValueTypeSet. |
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This crate turns a parsed query, as defined by the query crate and produced by the query-parser crate, into an algebrized tree, also called a query processor tree.
This is something of a wooly definition: a query algebrizer in a traditional relational database is the component that combines the schema — including column type constraints — with the query, resolving names and that sort of thing. Much of that work is unnecessary in our model; for example, we don't need to resolve column aliases, deal with table names, or that sort of thing. But the similarity is strong enough to give us the name of this crate.
The result of this process is traditionally handed to the query optimizer to yield an execution plan. In our case the execution plan is deterministically derived from the algebrized tree, and the real optimization (such as it is) takes place within the underlying SQLite database.