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https://issues.apache.org/jira/browse/FLINK-6442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16152746#comment-16152746
]
ASF GitHub Bot commented on FLINK-6442:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3829#discussion_r136847905
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/queryConfig.scala
---
@@ -19,9 +19,21 @@
package org.apache.flink.table.api
import _root_.java.io.Serializable
+
import org.apache.flink.api.common.time.Time
-class QueryConfig private[table] extends Serializable {}
+class QueryConfig private[table] extends Serializable {
+}
+
+object QueryConfig {
+ def getQueryConfigFromTableEnv(tableEnv: TableEnvironment): QueryConfig
= {
--- End diff --
The problem is that we should have the correct subtype of `QueryConfig`
(not only the returned object but also the method signature) and the separation
of the stream and batch APIs. The `StreamExecutionEnvironment.queryConfig`
method must be typed to `StreamQueryConfig` to prevent casting. However, we
don't want to have a method that is typed to `StreamQueryConfig` in the base
class `TableEnvironment` because 1) this class should be independent from the
streaming API and 2) we don't want a streaming method in the
`BatchTableEnvironment`.
So, we can add a method to `TableEnvironment` that returns `QueryConfig`
(depending on its own type a `StreamQueryConfig` or `BatchQueryConfig`) and
override this method in `StreamTableEnvironment` such that it returns a
`StreamQueryConfig` (and if later necessary in `BatchTableEnvironment` to
return a `BatchQueryConfig`).
The duplicated code are < 5 lines and we have correct types everywhere.
> Extend TableAPI Support Sink Table Registration and ‘insert into’ Clause in
> SQL
> -------------------------------------------------------------------------------
>
> Key: FLINK-6442
> URL: https://issues.apache.org/jira/browse/FLINK-6442
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: lincoln.lee
> Assignee: lincoln.lee
> Priority: Minor
>
> Currently in TableAPI there’s only registration method for source table,
> when we use SQL writing a streaming job, we should add additional part for
> the sink, like TableAPI does:
> {code}
> val sqlQuery = "SELECT * FROM MyTable WHERE _1 = 3"
> val t = StreamTestData.getSmall3TupleDataStream(env)
> tEnv.registerDataStream("MyTable", t)
> // one way: invoke tableAPI’s writeToSink method directly
> val result = tEnv.sql(sqlQuery)
> result.writeToSink(new YourStreamSink)
> // another way: convert to datastream first and then invoke addSink
> val result = tEnv.sql(sqlQuery).toDataStream[Row]
> result.addSink(new StreamITCase.StringSink)
> {code}
> From the api we can see the sink table always be a derived table because its
> 'schema' is inferred from the result type of upstream query.
> Compare to traditional RDBMS which support DML syntax, a query with a target
> output could be written like this:
> {code}
> insert into table target_table_name
> [(column_name [ ,...n ])]
> query
> {code}
> The equivalent form of the example above is as follows:
> {code}
> tEnv.registerTableSink("targetTable", new YourSink)
> val sql = "INSERT INTO targetTable SELECT a, b, c FROM sourceTable"
> val result = tEnv.sql(sql)
> {code}
> It is supported by Calcite’s grammar:
> {code}
> insert:( INSERT | UPSERT ) INTO tablePrimary
> [ '(' column [, column ]* ')' ]
> query
> {code}
> I'd like to extend Flink TableAPI to support such feature. see design doc:
> https://goo.gl/n3phK5
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