Syntax Reference

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The KSQL CLI provides a terminal-based interactive shell for running queries.

Table of Contents

CLI-specific commands
KSQL statements
Scalar functions
Aggregate functions
Configuring KSQL

CLI-specific commands

Unlike KSQL statements such as SELECT, these commands are for setting a KSQL configuration, exiting the CLI, etc. Run the CLI with --help to see the available options.

Tip: You can search and browse your command history in the KSQL CLI with Ctrl-R. After pressing Ctrl-R, start typing the command or any part of the command to show an auto-complete of past commands.

Description:
  The KSQL CLI provides a terminal-based interactive shell for running queries.  Each command must be on a separate
  line. For KSQL command syntax, see the documentation at https://github.com/confluentinc/ksql/docs/.

help:
  Show this message.

clear:
  Clear the current terminal.

output:
  View the current output format.

output <format>:
  Set the output format to <format> (valid formats: 'JSON', 'TABULAR')
  For example: "output JSON"

history:
  Show previous lines entered during the current CLI session. You can use up and down arrow keys to navigate to the
  previous lines too.

version:
  Get the current KSQL version.

exit:
  Exit the CLI.


Default behavior:

    Lines are read one at a time and are sent to the server as KSQL unless one of the following is true:

    1. The line is empty or entirely whitespace. In this case, no request is made to the server.

    2. The line ends with backslash (`\`). In this case, lines are continuously read and stripped of their trailing
    newline and `\` until one is encountered that does not end with `\`; then, the concatenation of all lines read
    during this time is sent to the server as KSQL.

KSQL statements

Important:

KSQL statements must be terminated with a semicolon (;).
Multi-line statements:
- In the CLI you must use a back-slash (\) to indicate continuation of a statement on the next line.
- Do not use \ for multi-line statements in .sql files.

DESCRIBE

Synopsis

DESCRIBE (stream_name|table_name);

Description

List the columns in a stream or table along with their data type and other attributes.

CREATE STREAM

Synopsis

CREATE STREAM stream_name ( { column_name data_type } [, ...] )
  WITH ( property_name = expression [, ...] );

Description

Create a new stream with the specified columns and properties.

The supported column data types are:

BOOLEAN
INTEGER
BIGINT
DOUBLE
VARCHAR (or STRING)
ARRAY<ArrayType> (JSON only)
MAP<VARCHAR, ValueType> (JSON only)

KSQL adds the implicit columns ROWTIME and ROWKEY to every stream and table, which represent the corresponding Kafka message timestamp and message key, respectively.

The WITH clause supports the following properties:

Property	Description
KAFKA_TOPIC (required)	The name of the Kafka topic that backs this stream. The topic must already exist in Kafka.
VALUE_FORMAT (required)	Specifies the serialization format of the message value in the topic. Supported formats: `JSON`, `DELIMITED`
KEY	Associates the message key in the Kafka topic with a column in the KSQL stream.
TIMESTAMP	Associates the message timestamp in the Kafka topic with a column in the KSQL stream. Time-based operations such as windowing will process a record according to this timestamp.

Example:

CREATE STREAM pageviews (viewtime BIGINT, user_id VARCHAR, page_id VARCHAR)
  WITH (VALUE_FORMAT = 'JSON',
        KAFKA_TOPIC = 'my-pageviews-topic');

CREATE TABLE

Synopsis

CREATE TABLE table_name ( { column_name data_type } [, ...] )
  WITH ( property_name = expression [, ...] );

Description

Create a new table with the specified columns and properties.

The supported column data types are:

BOOLEAN
INTEGER
BIGINT
DOUBLE
VARCHAR (or STRING)
ARRAY<ArrayType> (JSON only)
MAP<VARCHAR, ValueType> (JSON only)

KSQL adds the implicit columns ROWTIME and ROWKEY to every stream and table, which represent the corresponding Kafka message timestamp and message key, respectively.

The WITH clause supports the following properties:

Property	Description
KAFKA_TOPIC (required)	The name of the Kafka topic that backs this table. The topic must already exist in Kafka.
VALUE_FORMAT (required)	Specifies the serialization format of the message value in the topic. Supported formats: `JSON`, `DELIMITED`
KEY	Associates the message key in the Kafka topic with a column in the KSQL table.
TIMESTAMP	Associates the message timestamp in the Kafka topic with a column in the KSQL table. Time-based operations such as windowing will process a record according to this timestamp.

Example:

CREATE TABLE users (usertimestamp BIGINT, user_id VARCHAR, gender VARCHAR, region_id VARCHAR)
  WITH (VALUE_FORMAT = 'JSON',
        KAFKA_TOPIC = 'my-users-topic');

CREATE STREAM AS SELECT

Synopsis

CREATE STREAM stream_name
  [WITH ( property_name = expression [, ...] )]
  AS SELECT  select_expr [, ...]
  FROM from_item [, ...]
  [ WHERE condition ]
  [PARTITION BY column_name];

Description

Create a new stream along with the corresponding Kafka topic, and continuously write the result of the SELECT query into the stream and its corresponding topic.

If the PARTITION BY clause is present, then the resulting stream will have the specified column as its key.

The WITH clause supports the following properties:

Property	Description
KAFKA_TOPIC	The name of the Kafka topic that backs this stream. If this property is not set, then the name of the stream will be used as default.
VALUE_FORMAT	Specifies the serialization format of the message value in the topic. Supported formats: `JSON`, `DELIMITED`. If this property is not set, then the format of the input stream/table will be used.
PARTITIONS	The number of partitions in the topic. If this property is not set, then the number of partitions of the input stream/table will be used.
REPLICATIONS	The replication factor for the topic. If this property is not set, then the number of replicas of the input stream/table will be used.
TIMESTAMP	Associates the message timestamp in the Kafka topic with a column in the KSQL stream. Time-based operations such as windowing will process a record according to this timestamp.

Note: The KEY property is not supported -- use PARTITION BY instead.

CREATE TABLE AS SELECT

Synopsis

CREATE TABLE stream_name
  [WITH ( property_name = expression [, ...] )]
  AS SELECT  select_expr [, ...]
  FROM from_item [, ...]
  [ WINDOW window_expression ]
  [ WHERE condition ]
  [ GROUP BY grouping_expression ]
  [ HAVING having_expression ];

Description

Create a new KSQL table along with the corresponding Kafka topic and stream the result of the SELECT query as a changelog into the topic.

The WITH clause supports the following properties:

Property	Description
KAFKA_TOPIC	The name of the Kafka topic that backs this table. If this property is not set, then the name of the table will be used as default.
VALUE_FORMAT	Specifies the serialization format of the message value in the topic. Supported formats: `JSON`, `DELIMITED`. If this property is not set, then the format of the input stream/table will be used.
PARTITIONS	The number of partitions in the topic. If this property is not set, then the number of partitions of the input stream/table will be used.
REPLICATIONS	The replication factor for the topic. If this property is not set, then the number of replicas of the input stream/table will be used.
TIMESTAMP	Associates the message timestamp in the Kafka topic with a column in the KSQL table. Time-based operations such as windowing will process a record according to this timestamp.

DROP STREAM

Synopsis

DROP STREAM stream_name;

Description

Drops an existing stream.

DROP TABLE

Synopsis

DROP TABLE table_name;

Description

Drops an existing table.

SELECT

Synopsis

SELECT select_expr [, ...]
  FROM from_item [, ...]
  [ WINDOW window_expression ]
  [ WHERE condition ]
  [ GROUP BY grouping_expression ]
  [ HAVING having_expression ];

Description

Selects rows from a KSQL stream or table. The result of this statement will not be persisted in a Kafka topic and will only be printed out in the console. To stop the continuous query in the CLI press Ctrl-C.

In the above statements from_item is one of the following:

stream_name [ [ AS ] alias]
table_name [ [ AS ] alias]
from_item LEFT JOIN from_item ON join_condition

WHERE clause can refer to any column defined for a stream or table, including the two implicit columns ROWTIME and ROWKEY.

Example:

SELECT * FROM pageviews
  WHERE ROWTIME >= 1510923225000
    AND ROWTIME <= 1510923228000;

Tip: If you want to select older data, you can configure KSQL to query the stream from the beginning. You must do this configuration before running the query:
SET 'auto.offset.reset' = 'earliest';

The WINDOW clause lets you control how to group input records that have the same key into so-called windows for operations such as aggregations or joins. Windows are tracked per record key. KSQL supports the following WINDOW types:

TUMBLING: Tumbling windows group input records into fixed-sized, non-overlapping windows based on the records' timestamps. You must specify the window size for tumbling windows. Note: Tumbling windows are a special case of hopping windows where the window size is equal to the advance interval.

Example:
```
SELECT item_id, SUM(quantity)
  FROM orders
  WINDOW TUMBLING (SIZE 20 SECONDS)
  GROUP BY item_id;
```
HOPPING: Hopping windows group input records into fixed-sized, (possibly) overlapping windows based on the records' timestamps. You must specify the window size and the advance interval for hopping windows.

Example:
```
SELECT item_id, SUM(quantity)
  FROM orders
  WINDOW HOPPING (SIZE 20 SECONDS, ADVANCE BY 5 SECONDS)
  GROUP BY item_id;
```
SESSION: Session windows group input records into so-called sessions. You must specify the session inactivity gap parameter for session windows. For example, imagine you set the inactivity gap to 5 minutes. If, for a given record key such as "alice", no new input data arrives for more than 5 minutes, then the current session for "alice" is closed, and any newly arriving data for "alice" in the future will mark the beginning of a new session.

Example:
```
SELECT item_id, SUM(quantity)
  FROM orders
  WINDOW SESSION (20 SECONDS)
  GROUP BY item_id;
```

CAST

Synopsis

CAST (expression AS data_type);

You can cast an expression's type to a new type using CAST. Here is an example of converting a BIGINT into a VARCHAR type:

-- This query converts the numerical count into a suffixed string; e.g., 5 becomes '5_HELLO'
SELECT page_id, CONCAT(CAST(COUNT(*) AS VARCHAR), '_HELLO')
  FROM pageviews_enriched
  WINDOW TUMBLING (SIZE 20 SECONDS)
  GROUP BY page_id;

LIKE

Synopsis

column_name LIKE pattern;

The LIKE operator is used for prefix or suffix matching. Currently KSQL supports %, which represents zero or more characters.

Example:

SELECT user_id
  FROM users
  WHERE user_id LIKE 'santa%';

SHOW TOPICS

Synopsis

SHOW | LIST TOPICS;

Description

List the available topics in the Kafka cluster that KSQL is configured to connect to (default setting for bootstrap.servers: localhost:9092).

SHOW STREAMS

Synopsis

SHOW | LIST STREAMS;

Description

List the defined streams.

SHOW TABLES

Synopsis

SHOW | LIST TABLES;

Description

List the defined tables.

SHOW QUERIES

Synopsis

SHOW QUERIES;

Description

List the running persistent queries.

SHOW PROPERTIES

Synopsis

SHOW PROPERTIES;

Description

List the configuration settings that are currently in effect.

TERMINATE

Synopsis

TERMINATE query_id;

Description

Terminate a persistent query. Persistent queries run continuously until they are explicitly terminated.

In standalone mode, exiting the CLI will stop (think: "pause") any persistent queries because exiting the CLI will also stop the KSQL server. When the CLI is restarted, the server will be restarted, too, and any previously defined persistent queries will resume processing.
In client-server mode, exiting the CLI will not stop persistent queries because the KSQL server(s) will continue to process the queries.

(To terminate a non-persistent query use Ctrl-C in the CLI.)

Scalar functions

Function	Example	Description
ABS	`ABS(col1)`	The absolute value of a value
CEIL	`CEIL(col1)`	The ceiling of a value
CONCAT	`CONCAT(col1, '_hello')`	Concatenate two strings
EXTRACTJSONFIELD	`EXTRACTJSONFIELD(message, '$.log.cloud')`	Given a string column in JSON format, extract the field that matches
FLOOR	`FLOOR(col1)`	The floor of a value
LCASE	`LCASE(col1)`	Convert a string to lowercase
LEN	`LEN(col1)`	The length of a string
RANDOM	`RANDOM()`	Return a random DOUBLE value between 0 and 1.0
ROUND	`ROUND(col1)`	Round a value to the nearest BIGINT value
STRINGTOTIMESTAMP	`STRINGTOTIMESTAMP(col1, 'yyyy-MM-dd HH:mm:ss.SSS')`	Converts a string value in the given format into the BIGINT value representing the timestamp.
SUBSTRING	`SUBSTRING(col1, 2, 5)`	Return the substring with the start and end indices
TIMESTAMPTOSTRING	`TIMESTAMPTOSTRING(ROWTIME, 'yyyy-MM-dd HH:mm:ss.SSS')`	Converts a BIGINT timestamp value into the string representation of the timestamp in the given format.
TRIM	`TRIM(col1)`	Trim the spaces from the beginning and end of a string
UCASE	`UCASE(col1)`	Convert a string to uppercase

Aggregate functions

Function	Example	Description
COUNT	`COUNT(col1)`	Count the number of rows
MAX	`MAX(col1)`	Return the maximum value for a given column and window
MIN	`MIN(col1)`	Return the minimum value for a given column and window
SUM	`SUM(col1)`	Sums the column values

Configuring KSQL

You can set configuration properties for KSQL and your queries with the SET statement. This includes settings for Kafka's Streams API (e.g., cache.max.bytes.buffering) as well as settings for Kafka's producer client and consumer client (e.g., auto.offset.reset).

SET '<property-name>'='<property-value>';

Examples:

ksql> SET 'auto.offset.reset'='earliest';
ksql> SET 'commit.interval.ms'='5000';

Both property name and property value should be enclosed in single quotes.

Tip: SHOW PROPERTIES shows the current settings.

Once a property has been set, it will remain in effect for the remainder of the KSQL CLI session until you issue another SET statement to change it.

You can also use a properties file instead of the SET statement. The syntax of properties files follow Java conventions, which are slightly different to the syntax of the SET statement above.

# Show the example contents of a properties file
$ cat ksql.properties
auto.offset.reset=earliest

# Start KSQL in standalone mode with the custom properties above
$ ksql-cli local --properties-file ./ksql.properties

# Start a KSQL server node (for client-server mode) with the custom properties above
$ ksql-server-start ./ksql.properties

Note: Be careful when you are using KSQL in Docker because the properties file must be available inside the Docker container. If you don't want to customize your Docker setup so that it contains an appropriate properties file, you should not use a properties file but the SET statement.

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syntax-reference.md

syntax-reference.md

Syntax Reference

CLI-specific commands

KSQL statements

DESCRIBE

CREATE STREAM

CREATE TABLE

CREATE STREAM AS SELECT

CREATE TABLE AS SELECT

DROP STREAM

DROP TABLE

SELECT

CAST

LIKE

SHOW TOPICS

SHOW STREAMS

SHOW TABLES

SHOW QUERIES

SHOW PROPERTIES

TERMINATE

Scalar functions

Aggregate functions

Configuring KSQL

Files

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syntax-reference.md

File metadata and controls

Syntax Reference

CLI-specific commands

KSQL statements

DESCRIBE

CREATE STREAM

CREATE TABLE

CREATE STREAM AS SELECT

CREATE TABLE AS SELECT

DROP STREAM

DROP TABLE

SELECT

CAST

LIKE

SHOW TOPICS

SHOW STREAMS

SHOW TABLES

SHOW QUERIES

SHOW PROPERTIES

TERMINATE

Scalar functions

Aggregate functions

Configuring KSQL