Hi chrisr,
It seems there are no "single line" ways to solve your problem. To print
results on screen, you can use the DataStream.print() / DataSet.print()
method, and to limit the output you can add a FilterFunction. The code
looks like:
Table projection1 = customers
> .select("id,last_name")
> .filter("last_name !== 'foobar'");
> tableEnv.toAppendStream(projection1, Row.class).filter(new
> FilterFunction<Row>() {
> int count = 0;
> @Override
> public boolean filter(Row value) throws Exception {
> return count ++ < 10;
> }
> }).setParallelism(1).print();
Hope this helps,
Hequn
On Sun, Jun 24, 2018 at 7:05 AM, chrisr123 <chris.rueg...@gmail.com> wrote:
> Is there a simple way to output the first few rows of a Flink table to
> stdout
> when developing an application? I just want to see the first 10-20 rows on
> screen
> during development to make sure my logic is correct.
> There doesnt seem to be something like print(10) in the API to see the
> first
> n rows
> Here is simple sample program, but I am writing to a CSV table sink for
> testing right now.
>
> // Get Customers
> String customersPath = "input/customers.csv";
> // id,first_name,last_name,email,address,city,state,zip
> CsvTableSource customersTableSource = CsvTableSource.builder()
> .path(customersPath)
> .ignoreFirstLine()
> .fieldDelimiter(",")
> .field("id", Types.INT())
> .field("first_name", Types.STRING())
> .field("last_name", Types.STRING())
> .field("email", Types.STRING())
> .field("address", Types.STRING())
> .field("city", Types.STRING())
> .field("state", Types.STRING())
> .field("zip", Types.STRING())
> .build();
>
>
> // Register our table source
> tableEnv.registerTableSource("customers", customersTableSource);
> Table customers = tableEnv.scan("customers");
>
>
> // Perform Operations
> // SELECT id,last_name
> // FROM customers
> Table projection1 = customers
> .select("id,last_name")
> .filter("last_name !== 'foobar'");
>
>
> // Write to Sinks
> int parallelism = 1;
> TableSink<Row> sink = new CsvTableSink("output/customers_out.csv", ",",
> parallelism, WriteMode.OVERWRITE);
> projection1.writeToSink(sink);
>
>
>
> --
> Sent from: http://apache-flink-user-mailing-list-archive.2336050.
> n4.nabble.com/
>
