Data types

Knime supports multiple data types. This variety reflects in the multiple node port types, in the column types within a data table and in the flow variable types.

Node port types

Nodes can have multiple input and output ports of different types. Each node port type looks different. Only ports of the same type can be connected to each other. Here is a list of the most used port types.

Port type	Carries	Icon	Example node
Table	Data table		CSV Reader, Excel Reader
DB Data	An SQL query and allows you to preview the result		DB Reader, DB GroupBy
DB Session	The current DB Session, including data types, connection properties, etc.		DB Connector, PostgreSQL Connector
Flow Variable	Flow variables passed alongside a connection		(red in/out ports on every node)
Generic port	Can connect to all kinds of ports, except table and flow variable.		Capture Workflow Start, Variable Filter
Workflow	A workflow port object		Workflow Reader, Workflow Writer
Credential	Authentication credentials passed to downstream nodes		Google Authenticator, Salesforce Connector
Credential (Knime Hub)	A Knime Hub Credential		Hub Authenticator, Space Connector
File System	For downstream nodes to perform file system operations e.g. read, write		Local File System Connector
Email Session	Defining outgoing mail server and connection properties		Email Connector (Labs), Email Sender (Labs)
Filter definition	A filter definition produced by an interactive component view		Interactive filter widgets in a component
Image	An image object		JavaScript view node, Table View
Normalize	PMML document containing normalization parameters		Normalizer (PMML), Denormalizer
Outlier	A model of detected outlier boundaries/statistics		Numeric Outliers, Numeric Outliers Apply
Python Environment	A reference to a configured Python environment		Python Environment Propagation
Report	Report content		Report Template Creator, Report Concatenate

Column types

Knime tables support columns of multiple data types. The main column types available are:

• Number (Integer)
• Number (Long Integer)
• Number (Float)
• String
• Boolean
• Collection (List) and Collection (Set)
• HTML
• JSON
• XML
• URI
• Path
• Document
• Date
• Time
• Date&time (Local) and Date&time (Zoned)
• Duration (Time-based) and Duration (Date-based)
• Bit Vector and Bit Vector (Sparse)
• Byte Vector
• Image (PNG) and Image (SVG)
• Model (PMML)

Flow variable types

• BooleanType
• DoubleType
• IntType
• LongType
• StringType
• CredentialsType
• FSLocationVariableType
• Array counterparts of the above: BooleanArrayType, IntArrayType, LongArrayType, DoubleArrayType, StringArrayType

Note that not all column types have a corresponding flow variable type. When converting a table cell to flow variable, if the corresponding flow variable type is not available, the value is casted to StringType.