Appendix

Keywords

The following table shows all keywords in the language.

keyword	description	example
ADD	add a column to a stream or table	ADD (COLUMN)? identifier type;
ADVANCE	hop size in hopping window	WINDOW HOPPING (SIZE 30 SECONDS, ADVANCE BY 10 SECONDS)
ALL	list hidden topics	SHOW ALL TOPICS;
ALTER	change a property, stream, or table	ALTER 'auto.offset.reset'='latest';
AND	logical "and" operator	WHERE userid<>'User_1' AND userid<>'User_2'
ARRAY	one-indexed array of elements	SELECT ARRAY[1, 2] FROM s1 EMIT CHANGES;
AS	alias a column, expression, or type
ASSERT	assert value, stream, table, tombstone, topic, schema	ASSERT NULL VALUES sourceName (columns)? KEY values;
BEGINNING	print from start of topic	PRINT <topic-name> FROM BEGINNING;
BETWEEN	constrain a value to a range	SELECT event FROM events WHERE event_id BETWEEN 10 AND 20 …
BY	specify expression	GROUP BY regionid, ADVANCE BY 10 SECONDS, PARTITION BY userid
BYTES	bytes data type
CASE	select a condition from expressions	SELECT CASE WHEN condition THEN result [ WHEN … THEN … ] … END
CAST	change expression type	SELECT id, CONCAT(CAST(COUNT(*) AS VARCHAR), '_HELLO') FROM views …
CHANGES	specify incremental refinement type	SELECT * FROM users EMIT CHANGES;
CONNECTOR	manage a connector	CREATE SOURCE CONNECTOR 'jdbc-connector' WITH( …
CONNECTORS	list all connectors	SHOW CONNECTORS;
CREATE	create an object	CREATE STREAM rock_songs (artist VARCHAR, title VARCHAR) …
DATE	date data type
DAY	time unit of one day for a window	WINDOW TUMBLING (SIZE 30 SECONDS, RETENTION 1 DAY)
DAYS	time unit of days for a window	WINDOW TUMBLING (SIZE 30 SECONDS, RETENTION 1000 DAYS)
DECIMAL	decimal numeric type
DEFINE	define a variable	DEFINE name = 'Tom Sawyer';
DELETE	remove a Kafka topic	DROP TABLE <table-name> DELETE TOPIC;
DESCRIBE	list details for object(s)	DESCRIBE PAGEVIEWS;
DISTINCT	test for uniqueness	CREATE STREAM output AS SELECT A, A IS NOT DISTINCT FROM 1,…);
DROP	delete an object	DROP CONNECTOR <connector-name>;
ELSE	condition in WHEN statement	CASE WHEN units<2 THEN 'sm' WHEN units<4 THEN 'med' ELSE 'large' …
EMIT	specify push query	SELECT * FROM users EMIT CHANGES;
END	close a CASE block	SELECT CASE WHEN condition THEN result [ WHEN … THEN … ] … END
EXISTS	test whether object exists	DROP STREAM IF EXISTS <stream-name>;
EXPLAIN	show execution plan	EXPLAIN <query-name>; or EXPLAIN <expression>;
EXTENDED	list details for object(s)	DESCRIBE <stream-name> EXTENDED;
FALSE	Boolean value of false
FINAL	suppress intermediate results on a windowed aggregation	SELECT * FROM users EMIT FINAL;
FROM	specify record source for queries	SELECT * FROM users;
FULL	specify FULL JOIN	CREATE TABLE t AS SELECT * FROM l FULL OUTER JOIN r ON l.ID = r.ID;
FUNCTION	list details for a function	DESCRIBE FUNCTION <function-name>;
FUNCTIONS	list all functions	SHOW FUNCTIONS;
GRACE	grace period for a tumbling window	WINDOW TUMBLING (SIZE 1 HOUR, GRACE PERIOD 2 HOURS)
GROUP	group rows with the same values	SELECT regionid, COUNT(*) FROM pageviews GROUP BY regionid
HAVING	condition expression	GROUP BY card_number HAVING COUNT(*) > 3
HEADER	Specify a header column	CREATE STREAM S (H BYTES HEADER('abc')…)
HEADERS	Specify a headers column	CREATE STREAM S (H ARRAY<STRUCT<key STRING, value BYTES>> HEADERS…)
HOPPING	specify a hopping window	WINDOW HOPPING (SIZE 30 SECONDS, ADVANCE BY 10 SECONDS)
HOUR	time unit of one hour for a window	WINDOW TUMBLING (SIZE 1 HOUR, RETENTION 1 DAY)
HOURS	time unit of hours for a window	WINDOW TUMBLING (SIZE 2 HOURS, RETENTION 1 DAY)
IF	test whether object exists	DROP STREAM IF EXISTS <stream-name>;
IN	specify multiple values	WHERE name IN (value1, value2, ...)
INNER	specify INNER JOIN	CREATE TABLE t AS SELECT * FROM l INNER JOIN r ON l.ID = r.ID;
INSERT	insert new records in a stream/table	INSERT INTO <stream-name> ...
INTEGER	integer numeric type	CREATE TABLE profiles (id INTEGER PRIMARY KEY, …
INTERVAL	number of messages to skip in PRINT	PRINT <topic-name> INTERVAL 5;
INTO	stream/table to insert values	INSERT INTO stream_name ...
IS	use with keywords like NOT and DISTINCT	CREATE STREAM output AS SELECT A, A IS NOT DISTINCT FROM 1,…);
JOIN	match records in streams/tables	CREATE TABLE t AS SELECT * FROM l INNER JOIN r ON l.ID = r.ID;
KEY	specify key column	CREATE TABLE users (userId INT PRIMARY KEY, …
LEFT	specify LEFT JOIN	CREATE TABLE t AS SELECT * FROM l LEFT JOIN r ON l.ID = r.ID;
LIKE	match pattern	WHERE UCASE(gender)='FEMALE' AND LCASE (regionid) LIKE '%_6'
LIMIT	number of records to output	SELECT * FROM users EMIT CHANGES LIMIT 5;
LIST	list objects	LIST STREAMS; or SHOW STREAMS;
MAP	map data type	SELECT MAP(k1:=v1, k2:=v1*2) FROM s1 EMIT CHANGES;
MILLISECOND	time unit of one ms for a window	WINDOW TUMBLING (SIZE 1 MILLISECOND, RETENTION 1 DAY)
MILLISECONDS	time unit of ms for a window	WINDOW TUMBLING (SIZE 100 MILLISECONDS, RETENTION 1 DAY)
MINUTE	time unit of one min for a window	WINDOW TUMBLING (SIZE 1 MINUTE, RETENTION 1 DAY)
MINUTES	time unit of mins for a window	WINDOW TUMBLING (SIZE 30 MINUTES, RETENTION 1 DAY)
MONTH	time unit of one month for a window	WINDOW TUMBLING (SIZE 1 HOUR, RETENTION 1 MONTH)
MONTHS	time unit of months for a window	WINDOW TUMBLING (SIZE 1 HOUR, RETENTION 2 MONTHs)
NOT	logical "not" operator
NULL	field with no value	CREATE STREAM s AS SELECT * FROM t WHERE (t.c1 IS NOT NULL);
ON	specify join criteria	LEFT JOIN users ON pageviews.userid = users.userid
OR	logical "or" operator	WHERE userid='User_1' OR userid='User_2'
OUTER	specify OUTER JOIN	CREATE TABLE t AS SELECT * FROM l FULL OUTER JOIN r ON l.ID = r.ID;
PARTITION BY	repartition a stream	PARTITION BY <key-field>
PARTITIONS	partitions to distribute keys over	CREATE STREAM users_rekeyed WITH (PARTITIONS=6) AS …
PERIOD	grace period for a tumbling window	WINDOW TUMBLING (SIZE 1 HOUR, GRACE PERIOD 2 HOURS)
PLUGINS	show connector plugins	LIST CONNECTOR PLUGINS; or SHOW CONNECTOR PLUGINS;
PRIMARY	specify primary key column	CREATE TABLE users (userId INT PRIMARY KEY, …
PRINT	output records in a topic	PRINT <topic-name> FROM BEGINNING;
PROPERTIES	list all properties	LIST PROPERTIES; or SHOW PROPERTIES;
PAUSE	pause a persistent query	PAUSE query_id;
QUERIES	list all queries	LIST QUERIES; or SHOW QUERIES;
REPLACE	string replace	REPLACE(col1, 'foo', 'bar')
RESUME	resume a paused persistent query	RESUME query_id;
RETENTION	time to retain past windows	WINDOW TUMBLING (SIZE 30 SECONDS, RETENTION 1000 DAYS)
RIGHT	specify RIGHT JOIN	CREATE TABLE t AS SELECT * FROM l RIGHT JOIN r ON l.ID = r.ID;
RUN SCRIPT	execute queries from a file	RUN SCRIPT <path-to-query-file>;
SAMPLE	number of messages to skip in PRINT	PRINT <topic-name> SAMPLE 5;
SCHEMA	specify a schema	ASSERT SCHEMA SUBJECT 'foo-value' ID 5;
SECOND	time unit of one sec for a window	WINDOW TUMBLING (SIZE 1 SECOND, RETENTION 1 DAY)
SECONDS	time unit of secs for a window	WINDOW TUMBLING (SIZE 30 SECONDS, RETENTION 1 DAY)
SELECT	query a stream or table	SELECT * FROM metrics EMIT CHANGES;
SESSION	specify a session window	WINDOW SESSION (60 SECONDS)
SET	assign a property value	SET 'auto.offset.reset'='earliest';
SHOW	list objects	SHOW FUNCTIONS;
SINK	create a sink connector	CREATE SINK CONNECTOR …
SIZE	time length of a window	WINDOW TUMBLING (SIZE 5 SECONDS)
SOURCE	create a source connector	CREATE SOURCE CONNECTOR …
STREAM	register a stream on a topic	CREATE STREAM users_orig AS SELECT * FROM users EMIT CHANGES;
STREAMS	list all streams	SHOW STREAMS;
STRUCT	struct data type	SELECT STRUCT(f1 := v1, f2 := v2) FROM s1 EMIT CHANGES;
TABLE	register a table on a topic	CREATE TABLE users (id BIGINT PRIMARY KEY, …
TABLES	list all tables	SHOW TABLES;
TERMINATE	end a persistent query	TERMINATE query_id;
THEN	return expression in a CASE block	CASE WHEN units<2 THEN 'sm' WHEN units<4 THEN 'med' ELSE 'large' …
TIME	time data type
TIMEOUT	specify the amount of time to wait for an assertion to succeed	ASSERT SCHEMA ID 4 TIMEOUT 10 SECONDS;
TIMESTAMP	timestamp data type
TIMESTAMP	specify a timestamp column	CREATE STREAM pageviews WITH (TIMESTAMP='viewtime', …
TOPIC	specify a Kafka topic	DROP TABLE <table-name> DELETE TOPIC;
TOPICS	list all topics	LIST TOPICS; or SHOW TOPICS;
TRUE	Boolean value of true
TUMBLING	specify a tumbling window	WINDOW TUMBLING (SIZE 5 SECONDS)
TYPE	alias a complex type declaration	CREATE TYPE <type_name> AS <type>;
TYPES	list all custom type aliases	LIST TYPES; or SHOW TYPES;
UNDEFINE	undefine a variable	UNDEFINE name;
UNSET	unassign a property value	UNSET 'auto.offset.reset';
VALUES	list of values to insert	INSERT INTO foo VALUES ('key', 'A');
VARIABLES	list all variables	LIST VARIABLES; or SHOW VARIABLES;
WHEN	specify condition in a CASE block	SELECT CASE WHEN condition THEN result [ WHEN … THEN … ] …
WHERE	filter records by a condition	SELECT * FROM pageviews WHERE pageid < 'Page_20'
WINDOW	groups rows with the same keys	SELECT userid, COUNT(*) FROM users WINDOW SESSION (60 SECONDS) …
WITH	specify object creation params	CREATE STREAM pageviews WITH (TIMESTAMP='viewtime', …
WITHIN	time range in a windowed join	SELECT * FROM impressions i JOIN clicks c WITHIN 1 minute …
YEAR	time unit of one year for a window	WINDOW TUMBLING (SIZE 1 HOUR, RETENTION 1 YEAR)
YEARS	time unit of years for a window	WINDOW TUMBLING (SIZE 1 HOUR, RETENTION 2 YEARS)

Operators

The following table shows all operators in the language.

operator	meaning	applies to
=	is equal to	string, numeric
!= or <>	is not equal to	string, numeric
<	is less than	string, numeric
<=	is less than or equal to	string, numeric
>	is greater than	string, numeric
>=	is greater than or equal to	string, numeric
+	addition for numeric, concatenation for string	string, numeric
-	subtraction	numeric
*	multiplication	numeric
/	division	numeric
%	modulus	numeric
|| or +	concatenation	string
:=	assignment	all
->	struct field dereference	struct
.	source dereference	table, stream
=>	lambda expression	function
E or e	exponent	numeric
NOT	logical NOT	boolean
AND	logical AND	boolean
OR	logical OR	boolean
BETWEEN	test if value within range	numeric, string
LIKE	match a pattern	string
IN	short hand for multiple OR expressions	all
--	simple comment	string
/* */	bracketed comment	string
--@	directive comment	string

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Last update: 2022-08-16