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https://issues.apache.org/jira/browse/BEAM-6674?focusedWorklogId=256196&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-256196
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ASF GitHub Bot logged work on BEAM-6674:
----------------------------------------
Author: ASF GitHub Bot
Created on: 07/Jun/19 20:26
Start Date: 07/Jun/19 20:26
Worklog Time Spent: 10m
Work Description: reuvenlax commented on issue #8725: [BEAM-6674] Add
schema support to JdbcIO read
URL: https://github.com/apache/beam/pull/8725#issuecomment-500027187
What you suggested already works via Schema inference. If you have
PCollection<T> and T has a registered schema, then Beam will infer it
(assuming that T is not erased for some reason). However to convert the
Jdbc class to T requires knowing the actual type in the IO.
On Fri, Jun 7, 2019 at 4:42 AM Charith Ellawala <[email protected]>
wrote:
> *@charithe* commented on this pull request.
> ------------------------------
>
> In sdks/java/io/jdbc/src/main/java/org/apache/beam/sdk/io/jdbc/JdbcIO.java
> <https://github.com/apache/beam/pull/8725#discussion_r291556575>:
>
> > @@ -188,6 +191,15 @@
> .build();
> }
>
> + /** Read Beam {@link Row}s from a JDBC data source. */
> + @Experimental(Experimental.Kind.SCHEMAS)
> + public static ReadRows readRows() {
> + return new AutoValue_JdbcIO_ReadRows.Builder()
> + .setFetchSize(DEFAULT_FETCH_SIZE)
> + .setOutputParallelization(true)
> + .build();
> + }
>
> So I assumed that it would be easy to obtain the schema for T and
> implicitly attach it to the PCollection. However, this appears to be
> difficult to do reliably unless the user explicitly provides a reference to
> Class<T> as you correctly suggested.
>
> Given that the user has to make a conscious effort to enable schema
> support by providing a reference to Class<T>, wouldn't it make sense to
> introduce a generic utility function such as
PCollections.withSchema(PCollection<T>,
> Class<T>) that would work for any kind of PCollection and not just the
> output of JDBC IO?
>
> —
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Issue Time Tracking
-------------------
Worklog Id: (was: 256196)
Time Spent: 2h 40m (was: 2.5h)
> The JdbcIO source should produce schemas
> ----------------------------------------
>
> Key: BEAM-6674
> URL: https://issues.apache.org/jira/browse/BEAM-6674
> Project: Beam
> Issue Type: Sub-task
> Components: io-java-jdbc
> Reporter: Reuven Lax
> Assignee: Shehzaad Nakhoda
> Priority: Major
> Time Spent: 2h 40m
> Remaining Estimate: 0h
>
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