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https://issues.apache.org/jira/browse/CALCITE-4728?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17398283#comment-17398283
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Julian Hyde commented on CALCITE-4728:
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[~jamesstarr], Good point. I think we should separate this into:
# a syntax for defining functions and procedures (where the body of the
function is treated as a black box, and the function parser doesn't understand
the language but can just recognize the delimiter at the end), and
# a syntax for PL/SQL-style BEGIN ... END blocks (begin, end, if, then, while,
with embedded SQL). Blocks are hard to parse and validate because may have
embedded SQL.
Do you agree?
> Parse and validate procedural code (such as SQL/PSM, PL/SQL, PL/pgSQL, T-SQL)
> -----------------------------------------------------------------------------
>
> Key: CALCITE-4728
> URL: https://issues.apache.org/jira/browse/CALCITE-4728
> Project: Calcite
> Issue Type: Bug
> Reporter: Julian Hyde
> Priority: Major
>
> Parse and validate procedural code (such as the SQL standard's SQL/PSM,
> Oracle's PL/SQL, PostgreSQL's PL/pgSQL, MSSQL's T-SQL).
> This would entail:
> * Extensions to the SQL parser. (I'm not sure whether this would be the core
> parser or an extended parser such as Babel.)
> * AST classes (sub-classes of {{SqlNode}}) for functions, procedures,
> blocks, variable and parameter declarations, variable assignment,
> if-then-else, loop, and so forth.
> * Extensions to the validator to validate blocks.
> * Extensions to the validator to validate a SQL statement that is inside a
> block. (Variables and parameters are in scope.)
> Optional:
> * Extend Interpreter to execute functions, procedures, blocks.
> * Some means to convert a block into executable Java code.
> * Extend {{SqlDialect}} so that ASTs of functions, procedures and blocks can
> be emitted using the syntax of particular dialects.
> The languages are sufficiently similar that we can use the same AST classes
> for all.
> I don't think we need to extend {{RelNode}} to represent blocks. (It's not a
> good fit, since a block does not evaluate to a relation.) Possibly we would
> create some data structure to represent a validated block (e.g. the type of
> each variable; each use of a variable points to the variable's definition).
> {{SqlToRelConverter}} would create this data structure in order "freeze" the
> state of the validator.
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