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https://issues.apache.org/jira/browse/CALCITE-6239?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17823753#comment-17823753
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Julian Hyde commented on CALCITE-6239:
--------------------------------------
[~bchapuis], In my
[6239-postgis-dialect|https://github.com/julianhyde/calcite/tree/6239-postgis-dialect]
branch I have added a commit that attempts to decouple the GEOMETRY type from
the JTS Geometry class. Please take a look.
> Add a PostGIS dialect that supports ST_ functions
> -------------------------------------------------
>
> Key: CALCITE-6239
> URL: https://issues.apache.org/jira/browse/CALCITE-6239
> Project: Calcite
> Issue Type: New Feature
> Components: core, spatial
> Reporter: Bertil Chapuis
> Assignee: Bertil Chapuis
> Priority: Minor
> Labels: pull-request-available
>
> Calcite implements support for spatial types (geometry, point, etc.) and
> spatial functions (ST_), and it can connect to PostGIS via a JdbcSchema.
> However, the Postgresql dialect does not currently handle spatial types and
> functions. As a result, Calcite tries to execute the spatial functions at the
> level of the JVM instead of pushing them down to postgis.
> As a result, the following query gets executed, but the type of the geom
> column is incorrect:
> SELECT id, geom FROM public.spatial_table
> The following query fails with a ClassCastException as Calcite tries to use
> the java implementation of the ST_SRID function:
> SELECT id, ST_SRID(geom) FROM public.spatial_table
> java.lang.ClassCastException: class org.postgresql.util.PGobject cannot be
> cast to class org.locationtech.jts.geom.Geometry
> (org.postgresql.util.PGobject and org.locationtech.jts.geom.Geometry are in
> unnamed module of loader 'app')
> In my current understanding, this issue could be addressed with a new
> PostgisSqlDialect that extends PostgresqlSqlDialect and adds support for
> spatial types and functions. Here is a tentative roadmap:
> - Add all the spatial functions to the SqlKind class
> - Create a PostgisSqlDialect class that extends PostgresqlSqlDialect
> - Add support for the spatial types (geometry) by overriding the getCastSpec
> method of the SqlDialect class
> - Add support for the spatial functions by overriding the supportsFunction
> method of the SqlDialect class
> - Add support for the spatial aggregate functions by overriding the
> supportsAggregateFunction method of the SqlDialect class
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