SQL Client

SQL Client #

Flink’s Table & SQL API makes it possible to work with queries written in the SQL language, but these queries need to be embedded within a table program that is written in either Java or Scala. Moreover, these programs need to be packaged with a build tool before being submitted to a cluster. This more or less limits the usage of Flink to Java/Scala programmers.

The SQL Client aims to provide an easy way of writing, debugging, and submitting table programs to a Flink cluster without a single line of Java or Scala code. The SQL Client CLI allows for retrieving and visualizing real-time results from the running distributed application on the command line.

Animated demo of the Flink SQL Client CLI running table programs on a cluster

Getting Started #

This section describes how to setup and run your first Flink SQL program from the command-line.

The SQL Client is bundled in the regular Flink distribution and thus runnable out-of-the-box. It requires only a running Flink cluster where table programs can be executed. For more information about setting up a Flink cluster see the Cluster & Deployment part. If you simply want to try out the SQL Client, you can also start a local cluster with one worker using the following command:

./bin/start-cluster.sh

Starting the SQL Client CLI #

The SQL Client scripts are also located in the binary directory of Flink. Users have two options for starting the SQL Client CLI, either by starting an embedded standalone process or by connecting to a remote SQL Gateway. SQL Client default mode is embedded.

You can start the CLI in embedded mode by calling:

./bin/sql-client.sh

or explicitly use embedded mode:

./bin/sql-client.sh embedded

For gateway mode, you can start the CLI by calling:

./bin/sql-client.sh gateway --endpoint <gateway address>

In the gateway mode, the CLI submits the SQL to the specified remote gateway to execute statements.

The <gateway address> can be provided in two formats: as a host:port combination or as a full URL.

If you need to pass custom HTTP headers, you can do so by setting the FLINK_REST_CLIENT_HEADERS environment variable. For example:

export FLINK_REST_CLIENT_HEADERS="Cookie:myauthcookie=foobar;othercookie=baz"
./bin/sql-client.sh gateway --endpoint https://your-sql-gateway.endpoint.com/authenticated/sql

For multiple headers, separate them with a newline:

export FLINK_REST_CLIENT_HEADERS=$(cat << EOF
Cookie:myauthcookie=foobar
Cache-Control: no-cache
EOF)

By default, the SQL Client will use the truststore configured using the security.ssl.rest.truststore and security.ssl.rest.truststore-password properties in the Flink configuration file on the SQL client side. If these properties aren’t explicitly configured, the client will use the default certificate stores provided by the JDK.

Note SQL Client only supports connecting to the REST Endpoint since version v2.

See SQL Client startup options below for more details.

Running SQL Queries #

For validating your setup and cluster connection, you can enter the simple query below and press Enter to execute it.

SET 'sql-client.execution.result-mode' = 'tableau';
SET 'execution.runtime-mode' = 'batch';

SELECT
  name,
  COUNT(*) AS cnt
FROM
  (VALUES ('Bob'), ('Alice'), ('Greg'), ('Bob')) AS NameTable(name)
GROUP BY name;

The SQL Client will retrieve the results from the cluster and visualize them (you can close the result view by pressing the Q key):

+-------+-----+
|  name | cnt |
+-------+-----+
| Alice |   1 |
|   Bob |   2 |
|  Greg |   1 |
+-------+-----+

The SET command allows you to tune the job execution and the sql client behaviour. See SQL Client Configuration below for more details.

After a query is defined, it can be submitted to the cluster as a long-running, detached Flink job. The configuration section explains how to declare table sources for reading data, how to declare table sinks for writing data, and how to configure other table program properties.

Key-strokes #

There is a list of available key-strokes in SQL Client

Key-Stroke (Linux, Windows(WSL)) Key-Stroke (Mac) Description
alt-b, ctrl+⍇ Esc-b Backward word
alt-f, Ctrl+⍈ Esc-f Forward word
alt-c Esc-c Capitalize word
alt-l Esc-l Lowercase word
alt-u Esc-u Uppercase word
alt-d Esc-d Kill word
alt-n Esc-n History search forward (behaves same as down line from history in case of empty input)
alt-p Esc-p History search backward (behaves same as up line from history in case of empty input)
alt-t Esc-t Transpose words
ctrl-a ⌘-a To the beginning of line
ctrl-e ⌘-e To the end of line
ctrl-b ⌘-b Backward char
ctrl-f ⌘-f Forward char
ctrl-d ⌘-d Delete char
ctrl-h ⌘-h Backward delete char
ctrl-t ⌘-t Transpose chars
ctrl-i ⌘-i Invoke completion
ctrl-j ⌘-j Submit a query
ctrl-m ⌘-m Submit a query
ctrl-k ⌘-k Kill the line to the right from the cursor
ctrl-w ⌘-w Kill the line to the left from the cursor
ctrl-u ⌘-u Kill the whole line
ctrl-l ⌘-l Clear screen
ctrl-n ⌘-n Down line from history
ctrl-p ⌘-p Up line from history
ctrl-r ⌘-r History incremental search backward
ctrl-s ⌘-s History incremental search forward

Getting help #

The documentation of the SQL Client commands can be accessed by typing the HELP command.

See also the general SQL documentation.

Back to top

Configuration #

SQL Client startup options #

The SQL Client can be started with the following optional CLI commands. They are discussed in detail in the subsequent paragraphs.

./sql-client [MODE] [OPTIONS]

The following options are available:

Mode "embedded" (default) submits Flink jobs from the local machine.

  Syntax: [embedded] [OPTIONS]
  "embedded" mode options:
     -D <session dynamic config key=val>        The dynamic config key=val for a
                                                session.
     -f,--file <script file>                    Script file that should be
                                                executed. In this mode, the
                                                client will not open an
                                                interactive terminal.
     -h,--help                                  Show the help message with
                                                descriptions of all options.
     -hist,--history <History file path>        The file which you want to save
                                                the command history into. If not
                                                specified, we will auto-generate
                                                one under your user's home
                                                directory.
     -i,--init <initialization file>            Script file that used to init
                                                the session context. If get
                                                error in execution, the sql
                                                client will exit. Notice it's
                                                not allowed to add query or
                                                insert into the init file.
     -j,--jar <JAR file>                        A JAR file to be imported into
                                                the session. The file might
                                                contain user-defined classes
                                                needed for the execution of
                                                statements such as functions,
                                                table sources, or sinks. Can be
                                                used multiple times.
     -l,--library <JAR directory>               A JAR file directory with which
                                                every new session is
                                                initialized. The files might
                                                contain user-defined classes
                                                needed for the execution of
                                                statements such as functions,
                                                table sources, or sinks. Can be
                                                used multiple times.
     -pyarch,--pyArchives <arg>                 Add python archive files for
                                                job. The archive files will be
                                                extracted to the working
                                                directory of python UDF worker.
                                                For each archive file, a target
                                                directory be specified. If the
                                                target directory name is
                                                specified, the archive file will
                                                be extracted to a directory with
                                                the specified name. Otherwise,
                                                the archive file will be
                                                extracted to a directory with
                                                the same name of the archive
                                                file. The files uploaded via
                                                this option are accessible via
                                                relative path. '#' could be used
                                                as the separator of the archive
                                                file path and the target
                                                directory name. Comma (',')
                                                could be used as the separator
                                                to specify multiple archive
                                                files. This option can be used
                                                to upload the virtual
                                                environment, the data files used
                                                in Python UDF (e.g.,
                                                --pyArchives
                                                file:///tmp/py37.zip,file:///tmp
                                                /data.zip#data --pyExecutable
                                                py37.zip/py37/bin/python). The
                                                data files could be accessed in
                                                Python UDF, e.g.: f =
                                                open('data/data.txt', 'r').
     -pyclientexec,--pyClientExecutable <arg>   The path of the Python
                                                interpreter used to launch the
                                                Python process when submitting
                                                the Python jobs via "flink run"
                                                or compiling the Java/Scala jobs
                                                containing Python UDFs.
     -pyexec,--pyExecutable <arg>               Specify the path of the python
                                                interpreter used to execute the
                                                python UDF worker (e.g.:
                                                --pyExecutable
                                                /usr/local/bin/python3). The
                                                python UDF worker depends on
                                                Python 3.8+, Apache Beam
                                                (version == 2.43.0), Pip
                                                (version >= 20.3) and SetupTools
                                                (version >= 37.0.0). Please
                                                ensure that the specified
                                                environment meets the above
                                                requirements.
     -pyfs,--pyFiles <pythonFiles>              Attach custom files for job. The
                                                standard resource file suffixes
                                                such as .py/.egg/.zip/.whl or
                                                directory are all supported.
                                                These files will be added to the
                                                PYTHONPATH of both the local
                                                client and the remote python UDF
                                                worker. Files suffixed with .zip
                                                will be extracted and added to
                                                PYTHONPATH. Comma (',') could be
                                                used as the separator to specify
                                                multiple files (e.g., --pyFiles
                                                file:///tmp/myresource.zip,hdfs:
                                                ///$namenode_address/myresource2
                                                .zip).
     -pyreq,--pyRequirements <arg>              Specify a requirements.txt file
                                                which defines the third-party
                                                dependencies. These dependencies
                                                will be installed and added to
                                                the PYTHONPATH of the python UDF
                                                worker. A directory which
                                                contains the installation
                                                packages of these dependencies
                                                could be specified optionally.
                                                Use '#' as the separator if the
                                                optional parameter exists (e.g.,
                                                --pyRequirements
                                                file:///tmp/requirements.txt#fil
                                                e:///tmp/cached_dir).
     -s,--session <session identifier>          The identifier for a session.
                                                'default' is the default
                                                identifier.
     -u,--update <SQL update statement>         Deprecated Experimental (for
                                                testing only!) feature:
                                                Instructs the SQL Client to
                                                immediately execute the given
                                                update statement after starting
                                                up. The process is shut down
                                                after the statement has been
                                                submitted to the cluster and
                                                returns an appropriate return
                                                code. Currently, this feature is
                                                only supported for INSERT INTO
                                                statements that declare the
                                                target sink table.Please use
                                                option -f to submit update
                                                statement.


Mode "gateway" mode connects to the SQL gateway for submission.

  Syntax: gateway [OPTIONS]
  "gateway" mode options:
     -D <session dynamic config key=val>   The dynamic config key=val for a
                                           session.
     -e,--endpoint <SQL Gateway address>   The address of the remote SQL Gateway
                                           to connect.
     -f,--file <script file>               Script file that should be executed.
                                           In this mode, the client will not
                                           open an interactive terminal.
     -h,--help                             Show the help message with
                                           descriptions of all options.
     -hist,--history <History file path>   The file which you want to save the
                                           command history into. If not
                                           specified, we will auto-generate one
                                           under your user's home directory.
     -i,--init <initialization file>       Script file that used to init the
                                           session context. If get error in
                                           execution, the sql client will exit.
                                           Notice it's not allowed to add query
                                           or insert into the init file.
     -s,--session <session identifier>     The identifier for a session.
                                           'default' is the default identifier.
     -u,--update <SQL update statement>    Deprecated Experimental (for testing
                                           only!) feature: Instructs the SQL
                                           Client to immediately execute the
                                           given update statement after starting
                                           up. The process is shut down after
                                           the statement has been submitted to
                                           the cluster and returns an
                                           appropriate return code. Currently,
                                           this feature is only supported for
                                           INSERT INTO statements that declare
                                           the target sink table.Please use
                                           option -f to submit update statement.

SQL Client Configuration #

You can configure the SQL Client by setting the options below, or any valid Flink configuration entry:

SET 'key' = 'value';
Key Default Type Description
sql-client.display.color-schema

Batch Streaming
"DEFAULT" String SQL highlight color schema to be used at SQL client. Possible values: 'default', 'dark', 'light', 'chester', 'vs2010', 'solarized', 'obsidian', 'geshi'
sql-client.display.max-column-width

Batch Streaming
30 Integer Deprecated, please use table.display.max-column-width instead. When printing the query results, this parameter determines the number of characters shown on screen before truncating. This only applies to columns with variable-length types (e.g. CHAR, VARCHAR, STRING) in streaming mode. Fixed-length types and all types in batch mode are printed using a deterministic column width.
sql-client.display.print-time-cost

Batch
true Boolean Determine whether to display the time consumption of the query. By default, no query time cost will be displayed.
sql-client.display.show-line-numbers

Batch Streaming
false Boolean Determines whether there should be shown line numbers in multiline SQL or not.
sql-client.execution.max-table-result.rows

Batch Streaming
1000000 Integer The number of rows to cache when in the table mode. If the number of rows exceeds the specified value, it retries the row in the FIFO style.
sql-client.execution.result-mode

Batch Streaming
TABLE

Enum

Determines how the query result should be displayed.

Possible values:
  • "TABLE": Materializes results in memory and visualizes them in a regular, paginated table representation.
  • "CHANGELOG": Visualizes the result stream that is produced by a continuous query.
  • "TABLEAU": Display results in the screen directly in a tableau format.
sql-client.verbose

Batch Streaming
false Boolean Determine whether to output the verbose output to the console. If set the option true, it will print the exception stack. Otherwise, it only output the cause.

SQL Client result modes #

The CLI supports three modes for maintaining and visualizing results.

The table mode materializes results in memory and visualizes them in a regular, paginated table representation. It can be enabled by executing the following command in the CLI:

SET 'sql-client.execution.result-mode' = 'table';

The result of a query would then look like this, you can use the keys indicated at the bottom of the screen as well as the arrows keys to navigate and open the various records:


                           name         age isHappy        dob                         height
                          user1          20    true 1995-12-03                            1.7
                          user2          30    true 1972-08-02                           1.89
                          user3          40   false 1983-12-23                           1.63
                          user4          41    true 1977-11-13                           1.72
                          user5          22   false 1998-02-20                           1.61
                          user6          12    true 1969-04-08                           1.58
                          user7          38   false 1987-12-15                            1.6
                          user8          62    true 1996-08-05                           1.82




Q Quit                     + Inc Refresh              G Goto Page                N Next Page                O Open Row
R Refresh                  - Dec Refresh              L Last Page                P Prev Page

The changelog mode does not materialize results and visualizes the result stream that is produced by a continuous query consisting of insertions (+) and retractions (-).

SET 'sql-client.execution.result-mode' = 'changelog';

The result of a query would then look like this:

 op                           name         age isHappy        dob                         height
 +I                          user1          20    true 1995-12-03                            1.7
 +I                          user2          30    true 1972-08-02                           1.89
 +I                          user3          40   false 1983-12-23                           1.63
 +I                          user4          41    true 1977-11-13                           1.72
 +I                          user5          22   false 1998-02-20                           1.61
 +I                          user6          12    true 1969-04-08                           1.58
 +I                          user7          38   false 1987-12-15                            1.6
 +I                          user8          62    true 1996-08-05                           1.82




Q Quit                                       + Inc Refresh                                O Open Row
R Refresh                                    - Dec Refresh

The tableau mode is more like a traditional way which will display the results in the screen directly with a tableau format. The displaying content will be influenced by the query execution type (execution.type).

SET 'sql-client.execution.result-mode' = 'tableau';

The result of a query would then look like this:

+----+--------------------------------+-------------+---------+------------+--------------------------------+
| op |                           name |         age | isHappy |        dob |                         height |
+----+--------------------------------+-------------+---------+------------+--------------------------------+
| +I |                          user1 |          20 |    true | 1995-12-03 |                            1.7 |
| +I |                          user2 |          30 |    true | 1972-08-02 |                           1.89 |
| +I |                          user3 |          40 |   false | 1983-12-23 |                           1.63 |
| +I |                          user4 |          41 |    true | 1977-11-13 |                           1.72 |
| +I |                          user5 |          22 |   false | 1998-02-20 |                           1.61 |
| +I |                          user6 |          12 |    true | 1969-04-08 |                           1.58 |
| +I |                          user7 |          38 |   false | 1987-12-15 |                            1.6 |
| +I |                          user8 |          62 |    true | 1996-08-05 |                           1.82 |
+----+--------------------------------+-------------+---------+------------+--------------------------------+
Received a total of 8 rows

Note that when you use this mode with streaming query, the result will be continuously printed on the console. If the input data of this query is bounded, the job will terminate after Flink processed all input data, and the printing will also be stopped automatically. Otherwise, if you want to terminate a running query, just type CTRL-C in this case, the job and the printing will be stopped.

All these result modes can be useful during the prototyping of SQL queries. In all these modes, results are stored in the Java heap memory of the SQL Client. In order to keep the CLI interface responsive, the changelog mode only shows the latest 1000 changes. The table mode allows for navigating through bigger results that are only limited by the available main memory and the configured maximum number of rows (sql-client.execution.max-table-result.rows).

Attention Queries that are executed in a batch environment, can only be retrieved using the table or tableau result mode.

Initialize Session Using SQL Files #

A SQL query needs a configuration environment in which it is executed. SQL Client supports the -i startup option to execute an initialization SQL file to setup environment when starting up the SQL Client. The so-called initialization SQL file can use DDLs to define available catalogs, table sources and sinks, user-defined functions, and other properties required for execution and deployment.

An example of such a file is presented below.

-- Define available catalogs

CREATE CATALOG MyCatalog
  WITH (
    'type' = 'hive'
  );

USE CATALOG MyCatalog;

-- Define available database

CREATE DATABASE MyDatabase;

USE MyDatabase;

-- Define TABLE

CREATE TABLE MyTable(
  MyField1 INT,
  MyField2 STRING
) WITH (
  'connector' = 'filesystem',
  'path' = '/path/to/something',
  'format' = 'csv'
);

-- Define VIEW

CREATE VIEW MyCustomView AS SELECT MyField2 FROM MyTable;

-- Define user-defined functions here.

CREATE FUNCTION myUDF AS 'foo.bar.AggregateUDF';

-- Properties that change the fundamental execution behavior of a table program.

SET 'execution.runtime-mode' = 'streaming'; -- execution mode either 'batch' or 'streaming'
SET 'sql-client.execution.result-mode' = 'table'; -- available values: 'table', 'changelog' and 'tableau'
SET 'sql-client.execution.max-table-result.rows' = '10000'; -- optional: maximum number of maintained rows
SET 'parallelism.default' = '1'; -- optional: Flink's parallelism (1 by default)
SET 'pipeline.auto-watermark-interval' = '200'; --optional: interval for periodic watermarks
SET 'pipeline.max-parallelism' = '10'; -- optional: Flink's maximum parallelism
SET 'table.exec.state.ttl' = '1000'; -- optional: table program's idle state time
SET 'restart-strategy.type' = 'fixed-delay';

-- Configuration options for adjusting and tuning table programs.

SET 'table.optimizer.join-reorder-enabled' = 'true';
SET 'table.exec.spill-compression.enabled' = 'true';
SET 'table.exec.spill-compression.block-size' = '128kb';

This configuration:

  • connects to Hive catalogs and uses MyCatalog as the current catalog with MyDatabase as the current database of the catalog,
  • defines a table MyTable that can read data from a CSV file,
  • defines a view MyCustomView that declares a virtual table using a SQL query,
  • defines a user-defined function myUDF that can be instantiated using the class name,
  • uses streaming mode for running statements and a parallelism of 1,
  • runs exploratory queries in the table result mode,
  • and makes some planner adjustments around join reordering and spilling via configuration options.

When using -i <init.sql> option to initialize SQL Client session, the following statements are allowed in an initialization SQL file:

  • DDL(CREATE/DROP/ALTER),
  • USE CATALOG/DATABASE,
  • LOAD/UNLOAD MODULE,
  • SET command,
  • RESET command.

When execute queries or insert statements, please enter the interactive mode or use the -f option to submit the SQL statements.

Attention If SQL Client receives errors during initialization, SQL Client will exit with error messages.

Dependencies #

The SQL Client does not require setting up a Java project using Maven, Gradle, or sbt. Instead, you can pass the dependencies as regular JAR files that get submitted to the cluster. You can either specify each JAR file separately (using --jar) or define entire library directories (using --library). For connectors to external systems (such as Apache Kafka) and corresponding data formats (such as JSON), Flink provides ready-to-use JAR bundles. These JAR files can be downloaded for each release from the Maven central repository.

The full list of offered SQL JARs can be found on the connection to external systems page.

You can refer to the configuration section for information on how to configure connector and format dependencies.

Back to top

Usage #

SQL Client allows users to submit jobs either within the interactive command line or using -f option to execute sql file.

In both modes, SQL Client supports to parse and execute all types of the Flink supported SQL statements.

Interactive Command Line #

In interactive Command Line, the SQL Client reads user inputs and executes the statement terminated by a semicolon (;).

SQL Client will print success message if the statement is executed successfully. When getting errors, SQL Client will also print error messages. By default, the error message only contains the error cause. In order to print the full exception stack for debugging, please set the sql-client.verbose to true through command SET 'sql-client.verbose' = 'true';.

Execute SQL Files #

SQL Client supports to execute a SQL script file with the -f option. SQL Client will execute statements one by one in the SQL script file and print execution messages for each executed statements. Once a statement fails, the SQL Client will exit and all the remaining statements will not be executed.

An example of such a file is presented below.

CREATE TEMPORARY TABLE users (
  user_id BIGINT,
  user_name STRING,
  user_level STRING,
  region STRING,
  PRIMARY KEY (user_id) NOT ENFORCED
) WITH (
  'connector' = 'upsert-kafka',
  'topic' = 'users',
  'properties.bootstrap.servers' = '...',
  'key.format' = 'csv',
  'value.format' = 'avro'
);

-- set sync mode
SET 'table.dml-sync' = 'true';

-- set the job name
SET 'pipeline.name' = 'SqlJob';

-- set the queue that the job submit to
SET 'yarn.application.queue' = 'root';

-- set the job parallelism
SET 'parallelism.default' = '100';

-- restore from the specific savepoint path
SET 'execution.savepoint.path' = '/tmp/flink-savepoints/savepoint-cca7bc-bb1e257f0dab';

INSERT INTO pageviews_enriched
SELECT *
FROM pageviews AS p
LEFT JOIN users FOR SYSTEM_TIME AS OF p.proctime AS u
ON p.user_id = u.user_id;

This configuration:

  • defines a temporal table source users that reads from a CSV file,
  • set the properties, e.g job name,
  • set the savepoint path,
  • submit a sql job that load the savepoint from the specified savepoint path.

Attention Compared to the interactive mode, SQL Client will stop execution and exits when there are errors.

Execute a set of SQL statements #

SQL Client execute each INSERT INTO statement as a single Flink job. However, this is sometimes not optimal because some part of the pipeline can be reused. SQL Client supports STATEMENT SET syntax to execute a set of SQL statements. This is an equivalent feature with StatementSet in Table API. The STATEMENT SET syntax encloses one or more INSERT INTO statements. All statements in a STATEMENT SET block are holistically optimized and executed as a single Flink job. Joint optimization and execution allows for reusing common intermediate results and can therefore significantly improve the efficiency of executing multiple queries.

Syntax #

EXECUTE STATEMENT SET 
BEGIN
  -- one or more INSERT INTO statements
  { INSERT INTO|OVERWRITE <select_statement>; }+
END;

Attention The statements of enclosed in the STATEMENT SET must be separated by a semicolon (;). The old syntax BEGIN STATEMENT SET; ... END; is deprecated, may be removed in the future version.

Flink SQL> CREATE TABLE pageviews (
>   user_id BIGINT,
>   page_id BIGINT,
>   viewtime TIMESTAMP,
>   proctime AS PROCTIME()
> ) WITH (
>   'connector' = 'kafka',
>   'topic' = 'pageviews',
>   'properties.bootstrap.servers' = '...',
>   'format' = 'avro'
> );
[INFO] Execute statement succeed.

Flink SQL> CREATE TABLE pageview (
>   page_id BIGINT,
>   cnt BIGINT
> ) WITH (
>   'connector' = 'jdbc',
>   'url' = 'jdbc:mysql://localhost:3306/mydatabase',
>   'table-name' = 'pageview'
> );
[INFO] Execute statement succeed.

Flink SQL> CREATE TABLE uniqueview (
>   page_id BIGINT,
>   cnt BIGINT
> ) WITH (
>   'connector' = 'jdbc',
>   'url' = 'jdbc:mysql://localhost:3306/mydatabase',
>   'table-name' = 'uniqueview'
> );
[INFO] Execute statement succeed.

Flink SQL> EXECUTE STATEMENT SET
> BEGIN
>
> INSERT INTO pageview
> SELECT page_id, count(1)
> FROM pageviews
> GROUP BY page_id;
>
> INSERT INTO uniqueview
> SELECT page_id, count(distinct user_id)
> FROM pageviews
> GROUP BY page_id;
>
> END;
[INFO] Submitting SQL update statement to the cluster...
[INFO] SQL update statement has been successfully submitted to the cluster:
Job ID: 6b1af540c0c0bb3fcfcad50ac037c862
CREATE TABLE pageviews (
  user_id BIGINT,
  page_id BIGINT,
  viewtime TIMESTAMP,
  proctime AS PROCTIME()
) WITH (
  'connector' = 'kafka',
  'topic' = 'pageviews',
  'properties.bootstrap.servers' = '...',
  'format' = 'avro'
);

CREATE TABLE pageview (
  page_id BIGINT,
  cnt BIGINT
) WITH (
  'connector' = 'jdbc',
  'url' = 'jdbc:mysql://localhost:3306/mydatabase',
  'table-name' = 'pageview'
);

CREATE TABLE uniqueview (
  page_id BIGINT,
  cnt BIGINT
) WITH (
  'connector' = 'jdbc',
  'url' = 'jdbc:mysql://localhost:3306/mydatabase',
  'table-name' = 'uniqueview'
);

EXECUTE STATEMENT SET
BEGIN

INSERT INTO pageview
SELECT page_id, count(1)
FROM pageviews
GROUP BY page_id;

INSERT INTO uniqueview
SELECT page_id, count(distinct user_id)
FROM pageviews
GROUP BY page_id;

END;

Execute DML statements sync/async #

By default, SQL Client executes DML statements asynchronously. That means, SQL Client will submit a job for the DML statement to a Flink cluster, and not wait for the job to finish. So SQL Client can submit multiple jobs at the same time. This is useful for streaming jobs, which are long-running in general.

SQL Client makes sure that a statement is successfully submitted to the cluster. Once the statement is submitted, the CLI will show information about the Flink job.

Flink SQL> INSERT INTO MyTableSink SELECT * FROM MyTableSource;
[INFO] Table update statement has been successfully submitted to the cluster:
Cluster ID: StandaloneClusterId
Job ID: 6f922fe5cba87406ff23ae4a7bb79044

Attention The SQL Client does not track the status of the running Flink job after submission. The CLI process can be shutdown after the submission without affecting the detached query. Flink’s restart strategy takes care of the fault-tolerance. Please use the job statements to monitor the detached query status or stop the detached query.

However, for batch users, it’s more common that the next DML statement requires waiting until the previous DML statement finishes. In order to execute DML statements synchronously, you can set table.dml-sync option to true in SQL Client.

Flink SQL> SET 'table.dml-sync' = 'true';
[INFO] Session property has been set.

Flink SQL> INSERT INTO MyTableSink SELECT * FROM MyTableSource;
[INFO] Submitting SQL update statement to the cluster...
[INFO] Execute statement in sync mode. Please wait for the execution finish...
[INFO] Complete execution of the SQL update statement.

Attention If you want to terminate the job, just type CTRL-C to cancel the execution.

Start a SQL Job from a savepoint #

Flink supports to start the job with specified savepoint. In SQL Client, it’s allowed to use SET command to specify the path of the savepoint.

Flink SQL> SET 'execution.savepoint.path' = '/tmp/flink-savepoints/savepoint-cca7bc-bb1e257f0dab';
[INFO] Session property has been set.

-- all the following DML statements will be restroed from the specified savepoint path
Flink SQL> INSERT INTO ...

When the path to savepoint is specified, Flink will try to restore the state from the savepoint when executing all the following DML statements.

Because the specified savepoint path will affect all the following DML statements, you can use RESET command to reset this config option, i.e. disable restoring from savepoint.

Flink SQL> RESET execution.savepoint.path;
[INFO] Session property has been reset.

For more details about creating and managing savepoints, please refer to Job Lifecycle Management.

Define a Custom Job Name #

SQL Client supports to define job name for queries and DML statements through SET command.

Flink SQL> SET 'pipeline.name' = 'kafka-to-hive';
[INFO] Session property has been set.

-- all the following DML statements will use the specified job name.
Flink SQL> INSERT INTO ...

Because the specified job name will affect all the following queries and DML statements, you can also use RESET command to reset this configuration, i.e. use default job names.

Flink SQL> RESET pipeline.name;
[INFO] Session property has been reset.

If the option pipeline.name is not specified, SQL Client will generate a default name for the submitted job, e.g. insert-into_<sink_table_name> for INSERT INTO statements.

Monitoring Job Status #

SQL Client supports to list jobs status in the cluster through SHOW JOBS statements.

Flink SQL> SHOW JOBS;
+----------------------------------+---------------+----------+-------------------------+
|                           job id |      job name |   status |              start time |
+----------------------------------+---------------+----------+-------------------------+
| 228d70913eab60dda85c5e7f78b5782c | kafka-to-hive |  RUNNING | 2023-02-11T05:03:51.523 |
+----------------------------------+---------------+----------+-------------------------+

Terminating a Job #

SQL Client supports to stop jobs with or without savepoints through STOP JOB statements.

Flink SQL> STOP JOB '228d70913eab60dda85c5e7f78b5782c' WITH SAVEPOINT;
+-----------------------------------------+
|                          savepoint path |
+-----------------------------------------+
| file:/tmp/savepoint-3addd4-0b224d9311e6 |
+-----------------------------------------+

The savepoint path could be specified with state.savepoints.dir either in the cluster configuration or session configuration (the latter would take precedence).

For more details about stopping jobs, please refer to Job Statements.

SQL Syntax highlighting #

SQL Client can highlight SQL syntax with several color schemes. With sql-client.display.color-schema it could be set a color scheme. Available color schemes: chester, dracula, solarized, vs2010, obsidian, geshi, dark, light, default (no highlighting). In case of wrong name the fallback is to default.

Color schema \ Style Keyword Default Comment Hint Quoted SQL Identifier
Default Default Default Default Default Default Default
Chester Bold blue White Italic green Bold green Red Cyan
Dark Bold blue White Italic bright Bold bright Green Cyan
Dracula Bold magenta White Italic cyan Bold cyan Green Red
Geshi Bold #993333 White Italic #808080 Bold #808080 #66CC66 #000099
Light Bold red Black Italic bright Bold bright Green Cyan
Obsidian Bold green White Italic bright Bold bright Red Magenta
VS2010 Bold blue White Italic green Bold green Red Magenta
Solarized Bold yellow Blue Italic bright Bold bright Green Red

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