Quoted Identifiers in TDengine

[Stefan Bischof]

Hi all!

I'm currently trying to the timeseries database TDengine (https://tdengine.com/) from ontop. TDengine uses backticks instead of double quotes for quoted identifiers in SQL queries.

For example, a simple SQL query looks like this:

SELECT * FROM `mydb`.`my_table`;

and double quotes are not allowed by the SQL engine.

What works: I can establish a connection from ontop to the database and I can create and debug mappings from the Protege plugin.

What doesn't work: I can not start the reasoner because it can not find the table, exactly because of this backtick issue.

Now my question: is there an easy way to configure ontop to use backticks instead of double quotes for quoted identifiers?

I already tried to use the python scaffolding tool, but couldn't find an obvious way to configure this.

Best,

Stefan Bischof

[LB]

Hi,

I think in the Ontop properties file can can change parts of the used components for the creation of the SQL query. I can't find better docs but in the dev section you can see the different components that make up a DB system in Ontop: https://ontop-vkg.org/dev/db-adapter.html#declaring-an-implementation

I think for you the SQLQuotedIDFactory is relevant and MySQL and Apache Spark, among others, do also have backticks escaping.

So starting from the JDBC driver name (not sure if this is the correct one)

and probably changing the metadata provider to MySQL might work? You can try to add this line to your Ontop properties file

com.taosdata.jdbc-metadataProvider = it.unibz.inf.ontop.dbschema.impl.MySQLDBMetadataProvider

Lorenz

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