On Wed, May 26, 2010 at 6:02 PM, Tatsuo Ishii <is...@postgresql.org> wrote: > I'm thinking about exporting the raw parser and related modules as a C > library. Though this will not be an immediate benefit of PostgreSQL > itself, it will be a huge benefit for any PostgreSQL > applications/middle ware those need to parse SQL statements.
In the past I and people I have known/worked with have made strategic use of UDFs running on a live server that return the parse tree, semantically analyzed tree, and planned tree (I think) outNode textual representation for various projects, and found them highly useful. Syntactic, semantic, and operational meaning of a query was useful for our projects. Some of this code was linked with the server, and so reading the node using Postgres' parser was easy. Otherwise, a small parser needed be written for external projects. Perhaps a slightly more ideal state of affairs would be: * These hooks to acquire the syntactic/semantic/planned trees would be bundled "for free" * When writing code not linked against the server, a more common serialization format, ala JSON or whatnot A more ambitious project that I don't think is in the scope of any initial implementation would be to allow for cross referencing of these compilation passes, similar to how GNU Bison allows you to interrogate for the position of a lexeme when reporting errors. In my experience, code written that mangles one layer (say, semantic, or harder yet, plan) has a hard time doing the best error because getting from a node at the "bottom" to the right lexeme(s) at the "top" is very cumbersome. One could imagine this being useful for other purposes too, but that is how I felt it firsthand. Feels a lot harder, though. fdr -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
