Julian-
My connection process is expensive, so I would like to keep the same connection
open for the lifespan of the JDBC Connection (i.e., I want to use the same
connection for schema querying as well as table enumeration). However,
SchemaFactory.create(SchemaPlus, String, Map) doesn't seem to give me any
access path to an OptiqConnection. How can I use the same connection for the
duration of the JDBC connection without storing it in my Schema implementation?
I notice that the mongodb driver holds onto the DB connection in its own
MongoSchema subclass.
And yes, I am the original author of sqlline (as well as jline). I'm delighted
that you find it useful!
-Marc
On Jul 4, 2014, at 5:55 PM, Julian Hyde <[email protected]> wrote:
> If you're working on a recent version of Optiq, schemas exist outside of
> connections. None of the objects in the schema (e.g. tables) should have a
> reference to an open connection. When you want to get data from these tables,
> an Optiq connection will be passed in. You can store the connection to the
> underlying system in the Optiq connection, or can create a connection for the
> duration of the scan, and make sure that you close it when the scan
> completes.
>
> See for example s.asQueryable. The Enumerator is from ResultSetEnumerable,
> which takes a DataSource as an argument, creates a java.sql.Connection, and
> calls java.sql.Connection.close() from ResultSetEnumerator.close().
>
> While you are initializing a schema, you will probably create a short-lived
> connection, populate metadata, and then close the connection.
> JdbcSchema.computeTables is an example of this. The metadata objects (in this
> case instances of JdbcTable) do not keep a reference to that connection.
>
> Hope that helps.
>
> By the way, I presume you are the same Marc Prud'hommeaux who started the
> sqlline project many years ago. Thank you! We are still enjoying (and
> improving) that project.
>
> Julian
>
> On Jul 4, 2014, at 12:16 PM, Marc Prud’hommeaux <[email protected]> wrote:
>
>> Optiq Folk-
>>
>> I'm writing an Optiq adapter, modeled on the excellent optiq-csv sample. I'm
>> wondering when and where I should close the connection to the underlying
>> datasource? The connection is being created in my AbstractSchema subclass,
>> but there doesn't appear to be any close() or disconnect() method in there
>> for me to override.
>>
>> -Marc
>>
>
