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https://issues.apache.org/jira/browse/CALCITE-2280?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16650969#comment-16650969
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Julian Hyde commented on CALCITE-2280:
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We can definitely add HIVE as a conformance level. As for adding Hive QL
features to Calcite's core SQL parser, it depends on the particular feature:
* If a feature is in the SQL standard, then we should add it.
* If a feature is generally useful, and occurs in several databases, then we
should add it, enabled by a conformance flag. ({{ORDER BY ordinal}} is an
example of such a feature.)
* If a feature is peculiar to just one database, and does not offer a
significant extra functionality, or makes the parser ambiguous or more complex
for other dialects, then we probably will not add it to Calcite's dialect.
Note that Hive QL is now called Hive SQL, because Hive is trying to move closer
to standard SQL over time. I don't think we should be adding to Calcite support
for features that the Hive team no longer recommends that people use in Hive.
For such features, Babel is probably a better home.
> Liberal "babel" parser that accepts all SQL dialects
> ----------------------------------------------------
>
> Key: CALCITE-2280
> URL: https://issues.apache.org/jira/browse/CALCITE-2280
> Project: Calcite
> Issue Type: Bug
> Components: babel
> Reporter: Julian Hyde
> Assignee: Julian Hyde
> Priority: Major
> Fix For: 1.17.0
>
>
> Create a parser that accepts all SQL dialects.
> It would accept common dialects such as Oracle, MySQL, PostgreSQL, BigQuery.
> If you have preferred dialects, please let us know in the comments section.
> (If you're willing to work on a particular dialect, even better!)
> We would do this in a new module, inheriting and extending the parser in the
> same way that the DDL parser in the "server" module does.
> This would be a messy and difficult project, because we would have to comply
> with the rules of each parser (and its set of built-in functions) rather than
> writing the rules as we would like them to be. That's why I would keep it out
> of the core parser. But it would also have large benefits.
> This would be new territory Calcite: as a tool for manipulating/understanding
> SQL, not (necessarily) for relational algebra or execution.
> Some possible uses:
> * analyze query lineage (what tables and columns are used in a query);
> * translate from one SQL dialect to another (using the JDBC adapter to
> generate SQL in the target dialect);
> * a "deep" compatibility mode (much more comprehensive than the current
> compatibility mode) where Calcite could pretend to be, say, Oracle;
> * SQL parser as a service: a REST call gives a SQL query, and returns a JSON
> or XML document with the parse tree.
> If you can think of interesting uses, please discuss in the comments.
> There are similarities with Uber's
> [QueryParser|https://eng.uber.com/queryparser/] tool. Maybe we can
> collaborate, or make use of their test cases.
> We will need a lot of sample queries. If you are able to contribute sample
> queries for particular dialects, please discuss in the comments section. It
> would be good if the sample queries are based on a familiar schema (e.g.
> scott or foodmart) but we can be flexible about this.
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