Package org.apache.flink.table.api.internal

Class TableResultImpl

    • Method Detail

      • getJobClient

        public Optional<org.apache.flink.core.execution.JobClient> getJobClient()
        Description copied from interface: TableResult
        For DML and DQL statement, return the JobClient which associates the submitted Flink job. For other statements (e.g. DDL, DCL) return empty.
        Specified by:
        getJobClient in interface TableResult

      • await

        public void await()
           throws InterruptedException,
                  ExecutionException
        Description copied from interface: TableResult
        Wait if necessary until the data is ready.

        For a select operation, this method will wait until the first row can be accessed locally. For an insert operation, this method will wait for the job to finish, because the result contains only one row. For other operations, this method will return immediately, because the result is already available locally.

        Specified by:
        await in interface TableResult
        Throws:
        InterruptedException - if the operation was interrupted while waiting
        ExecutionException - if a problem occurred

      • await

        public void await​(long timeout,
                  TimeUnit unit)
           throws InterruptedException,
                  ExecutionException,
                  TimeoutException
        Description copied from interface: TableResult
        Wait if necessary for at most the given time for the data to be ready.

        For a select operation, this method will wait until the first row can be accessed locally. For an insert operation, this method will wait for the job to finish, because the result contains only one row. For other operations, this method will return immediately, because the result is already available locally.

        Specified by:
        await in interface TableResult
        Parameters:
        timeout - the maximum time to wait
        unit - the time unit of the timeout argument
        Throws:
        InterruptedException - if the operation was interrupted while waiting
        ExecutionException - if a problem occurred
        TimeoutException - if the wait timed out

      • getResolvedSchema

        public org.apache.flink.table.catalog.ResolvedSchema getResolvedSchema()
        Description copied from interface: TableResult
        Returns the schema of the result.

        The schema of DDL, USE, EXPLAIN: 

         +-------------+-------------+----------+
 | column name | column type | comments |
 +-------------+-------------+----------+
 | result      | STRING      |          |
 +-------------+-------------+----------+

        The schema of SHOW: 

         +---------------+-------------+----------+
 |  column name  | column type | comments |
 +---------------+-------------+----------+
 | <object name> | STRING      |          |
 +---------------+-------------+----------+
 The column name of `SHOW CATALOGS` is "catalog name",
 the column name of `SHOW DATABASES` is "database name",
 the column name of `SHOW TABLES` is "table name",
 the column name of `SHOW VIEWS` is "view name",
 the column name of `SHOW FUNCTIONS` is "function name",
 the column name of `SHOW MODULES` is "module name".

        The schema of DESCRIBE: 

         +------------------+-------------+-----------------------------------------------------------------------------+
 | column name      | column type |                              comments                                       |
 +------------------+-------------+-----------------------------------------------------------------------------+
 | name             | STRING      | field name                                                                  |
 | type             | STRING      | field type expressed as a String                                            |
 | null             | BOOLEAN     | field nullability: true if a field is nullable, else false                  |
 | key              | BOOLEAN     | key constraint: 'PRI' for primary keys, 'UNQ' for unique keys, else null    |
 | extras           | STRING      | extras such as computed or metadata column information, else null           |
 | watermark        | STRING      | watermark: string expression if a field is watermark, else null             |
 +------------------+-------------+-----------------------------------------------------------------------------+

        The schema of INSERT: (one column per one sink) 

         +----------------------------+-------------+-----------------------+
 | column name                | column type | comments              |
 +----------------------------+-------------+-----------------------+
 | (name of the insert table) | BIGINT      | the insert table name |
 +----------------------------+-------------+-----------------------+

        The schema of SELECT is the selected field names and types.

        Specified by:
        getResolvedSchema in interface TableResult

      • collect

        public org.apache.flink.util.CloseableIterator<org.apache.flink.types.Row> collect()
        Description copied from interface: TableResult
        Get the result contents as a closeable row iterator.

        NOTE:

        • For SELECT operation, the job will not be finished unless all result data has been collected. So we should actively close the job to avoid resource leak through CloseableIterator#close method. Calling CloseableIterator#close method will cancel the job and release related resources.
        • For DML operation, Flink does not support getting the real affected row count now. So the affected row count is always -1 (unknown) for every sink, and them will be returned until the job is finished. Calling CloseableIterator#close method will cancel the job.
        • For other operations, no flink job will be submitted (TableResult.getJobClient() is always empty), and the result is bounded. Do nothing when calling CloseableIterator#close method.

        Recommended code to call CloseableIterator#close method looks like: 

        
 TableResult result = tEnv.execute("select ...");
 // using try-with-resources statement
 try (CloseableIterator<Row> it = result.collect()) {
     it... // collect same data
 }

        This method has slightly different behaviors under different checkpointing settings (to enable checkpointing for a streaming job, set checkpointing properties through TableConfig).

        • For batch jobs or streaming jobs without checkpointing, this method has neither exactly-once nor at-least-once guarantee. Query results are immediately accessible by the clients once they're produced, but exceptions will be thrown when the job fails and restarts.
        • For streaming jobs with exactly-once checkpointing, this method guarantees an end-to-end exactly-once record delivery. A result will be accessible by clients only after its corresponding checkpoint completes.
        • For streaming jobs with at-least-once checkpointing, this method guarantees an end-to-end at-least-once record delivery. Query results are immediately accessible by the clients once they're produced, but it is possible for the same result to be delivered multiple times.

        In order to fetch result to local, you can call either TableResult.collect() and TableResult.print(). But, they can't be called both on the same TableResult instance, because the result can only be accessed once.

        Specified by:
        collect in interface TableResult

      • collectInternal

        public org.apache.flink.util.CloseableIterator<org.apache.flink.table.data.RowData> collectInternal()
        Description copied from interface: TableResultInternal
        Returns an iterator that returns the iterator with the internal row data type.
        Specified by:
        collectInternal in interface TableResultInternal

      • print

        public void print()
        Description copied from interface: TableResult
        Print the result contents as tableau form to client console.

        This method has slightly different behaviors under different checkpointing settings (to enable checkpointing for a streaming job, set checkpointing properties through TableConfig).

        • For batch jobs or streaming jobs without checkpointing, this method has neither exactly-once nor at-least-once guarantee. Query results are immediately accessible by the clients once they're produced, but exceptions will be thrown when the job fails and restarts.
        • For streaming jobs with exactly-once checkpointing, this method guarantees an end-to-end exactly-once record delivery. A result will be accessible by clients only after its corresponding checkpoint completes.
        • For streaming jobs with at-least-once checkpointing, this method guarantees an end-to-end at-least-once record delivery. Query results are immediately accessible by the clients once they're produced, but it is possible for the same result to be delivered multiple times.

        In order to fetch result to local, you can call either TableResult.collect() and TableResult.print(). But, they can't be called both on the same TableResult instance, because the result can only be accessed once.

        Specified by:
        print in interface TableResult