Create a new table with the specified columns and properties.
A ksqlDB TABLE works much like tables in other SQL systems. A table has zero or more rows. Each
row is identified by its
PRIMARY KEY. A row's
PRIMARY KEY can not be
NULL. A message in the
underlying Kafka topic with the same key as an existing row will replace the existing row in the
table, or delete the row if the message's value is
NULL, i.e. a tombstone, as long as it has
a later timestamp /
This situation is handled differently by ksqlDB STREAM, as shown in the following table.
|Key column type
|NON NULL key constraint
Messages in the Kafka topic with a NULL
PRIMARY KEY are ignored.
|Unique key constraint
Messages with the same key as another have no special meaning.
Later messages with the same key replace earlier.
Messages with NULL values are ignored.
NULL message values are treated as a tombstone
Any existing row with a matching key is deleted.
Each column is defined by:
column_name: the name of the column. If unquoted, the name must be a valid
SQL identifier and ksqlDB converts it to uppercase.
The name can be quoted if case needs to be preserved or if the name is not a valid SQL
identifier, for example
data_type: the SQL type of the column. Columns can be any of the
data types supported by ksqlDB.
PRIMARY KEY: columns that are stored in the Kafka message's key should be marked as
PRIMARY KEY columns. If a column is not marked as a
PRIMARY KEY column ksqlDB loads it
from the Kafka message's value. Unlike a stream's
KEY column, a table's
PRIMARY KEY column(s)
are NON NULL. Any records in the Kafka topic with NULL key columns are dropped.
Each row within the table has a
ROWTIME pseudo column, which represents the last modified time
of the row. The timestamp has milliseconds accuracy. The timestamp is used by ksqlDB when updating
a row, during any windowing operations and during joins, where data from each side of a join is
generally processed in time order.
ROWTIME is populated from the corresponding Kafka message timestamp. Set
WITH clause to populate
ROWTIME from a column in the Kafka message key or value.
The WITH clause supports the following properties:
|The name of the Kafka topic that backs this source. The topic must either already exist in Kafka, or PARTITIONS must be specified to create the topic. Command will fail if the topic exists with different partition/replica counts.
|Specifies the serialization format of message values in the topic. For supported formats, see Serialization Formats.
|The number of partitions in the backing topic. This property must be set if creating a TABLE without an existing topic (the command will fail if the topic does not exist).
|The number of replicas in the backing topic. If this property is not set but PARTITIONS is set, then the default Kafka cluster configuration for replicas will be used for creating a new topic.
|Used when VALUE_FORMAT='DELIMITED'. Supports single character to be a delimiter, defaults to ','. For space and tab delimited values you must use the special values 'SPACE' or 'TAB', not an actual space or tab character.
|By default, the pseudo
ROWTIME column is the timestamp of the message in the Kafka topic. The TIMESTAMP property can be used to override
ROWTIME with the contents of the specified column within the Kafka message (similar to timestamp extractors in Kafka's Streams API). Timestamps have a millisecond accuracy. Time-based operations, such as windowing, will process a record according to the timestamp in
|Used in conjunction with TIMESTAMP. If not set the timestamp column must be of type
bigint. If it is set, then the TIMESTAMP column must be of type
varchar and have a format that can be parsed with the java
DateTimeFormatter. If your timestamp format has characters requiring single quotes, you can escape them with successive single quotes,
'', for example:
'yyyy-MM-dd''T''HH:mm:ssX'. For more information on timestamp formats, see DateTimeFormatter.
|Controls how values are deserialized where the values schema contains only a single column. The setting controls how ksqlDB will deserialize the value of the records in the supplied
KAFKA_TOPIC that contain only a single column.
If set to
true, ksqlDB expects the column to have been serialized as named column within a record.
If set to
false, ksqlDB expects the column to have been serialized as an anonymous value.
If not supplied, the system default, defined by ksql.persistence.wrap.single.values, then the format's default is used.
null values have special meaning in ksqlDB. Care should be taken when dealing with single-column schemas where the value can be
null. For more information, see Single column (un)wrapping.
Note: Supplying this property for formats that do not support wrapping, for example
DELIMITED, or when the value schema has multiple columns, will result in an error.
|By default, the topic is assumed to contain non-windowed data. If the data is windowed, i.e. was created using ksqlDB using a query that contains a
WINDOW clause, then the
WINDOW_TYPE property can be used to provide the window type. Valid values are
|By default, the topic is assumed to contain non-windowed data. If the data is windowed, i.e., was created using ksqlDB using a query that contains a
WINDOW clause, and the
WINDOW_TYPE property is TUMBLING or HOPPING, then the WINDOW_SIZE property should be set. The property is a string with two literals, window size (a number) and window size unit (a time unit). For example:
- To use Avro or Protobuf, you must have Schema Registry enabled and
ksql.schema.registry.url must be set in the ksqlDB server configuration
file. See Configure ksqlDB for Avro, Protobuf, and JSON schemas.
- Avro and Protobuf field names are not case sensitive in ksqlDB. This matches the ksqlDB column name behavior.
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