2.10 - Spark SQL Connector and Link Properties - Teradata QueryGrid

Teradata® QueryGrid™ Installation and User Guide

Teradata QueryGrid
September 2019
User Guide
When you create links and associated properties in the QueryGrid portlet, you are creating Configuration Name Value Pairs (NVP). NVP does the following:
  • Specifies the behavior of the target connector component
  • Configures how data is transformed
  • Configures the underlying link data transportation layer
  • Affects how the initiator connector performs

Links are named configurations that include an initiating connector and a target connector. If the same property is set for a link and a connector, the link setting overrides the connector setting.

Properties may be available for initiating connectors only, target connectors only, or both.
Name Default Description Overridable?

Property Name

Connector Type
16.20+ LOB Support True On Teradata Databases version 16.20 and later, the STRING and BINARY columns on Spark SQL are mapped to CLOB and BLOB by default. Deselect this option to map the STRING and BINARY columns to VARCHAR and VARBYTE, respectively.

Disable this option if there are a large number of STRING/BINARY columns in the Spark table.


Authentication Mechanism None Overall security mechanism for the cluster.

For HDInsight clusters when using the Enterprise Security Package (ESP), select Kerberos.

Collect Approximate Activity Count False Displays the approximate number of rows exported to the target data source.

When set to false, the activity count displays a 1. When set to true, an approximate activity count is returned. The default is false.


Compression Codec System Default Compression type to use when exporting to a Spark target table. Valid values are System Default, Deflate, BZip2, GZip, LZ4, and Snappy.


Conf File Paths /etc/hadoop/conf/,


Paths to core-site.xml, hdfs-site.xml, and hive-site.xml (if available) in a comma-separated list.   Target
Connection Evict Frequency 30 minutes

Frequency of eviction checks. Connection objects from the pool are checked, closed, and removed if the idle time (current time - last time of use) of a connection object is greater than the Connection Max Idle Time setting.

Reduce the time between checks if there are multiple concurrent users running queries to clear the connections more frequently.

Valid values are 1–1440 minutes.

Connection Max Idle Time 86400 seconds

The maximum idle time for the connection cache object, after which the object is closed and removed from the cache. Use this property when there are multiple concurrent users and queries running on the system that might lead to starvation of connection objects.

Valid values are 1–86400 seconds.

Connection Pool Size 100

Maximum number of connection objects that can be stored in a connection pool. When acquiring a new connection, the connector checks for an available space in the pool. If no space is available in the connection pool, the connection fails after 5 minutes. Only one connection pool and username per connector configuration is allowed.

Valid values are 1–10000.

Database Name Default Name of the database for the connector, if not provided in the user query.

Maximum name length is 255 characters.


Default Binary Size 64000 bytes The default truncation size for the VARBINARY types.

Valid values are 1–2097088000 bytes.

This is for a Teradata-to-Spark link and is used by the target Spark connector and is applicable when the initiating Teradata Database does not support BLOB data types with QueryGrid. With BLOB support, the default binary size is not used.


Default String Size 32000 characters The VARCHAR truncation size. This is the size at which data imported from or exported to string columns is truncated. The value represents the maximum number of Unicode characters to import, and defaults to 32000 characters. Teradata QueryGrid truncates the string columns at the default value set in defaultStringSize.

Valid values are 1–1048544000 characters.

This is for a Teradata-to-Spark link and is used by the target Spark connector and is applicable when the initiating Teradata Database does not support CLOB data types with QueryGrid. With CLOB support, the default string size is not used.


Disable Pushdown False When set to true, disables the pushdown of all query conditions to the target system.

Certain system-level, session-level, and column-level query attributes, such as CASESPECIFIC, can affect character string comparison results. These attributes can cause some queries to return incorrect results due to incorrect row filtering on the target system.

To avoid incorrect results caused by condition pushdown in situations where the settings on the initiating system do not match the settings on the target system, you can disable the pushdown of all conditions to the target system.

If designated as Overridable, this property can only be overridden at the session level from false to true (indicating you are disabling pushdown), but cannot be changed from true to false.


Enable Logging INFO Runs queries with debugging mode enabled.

Valid values are NONE, WARN, INFO, and DEBUG.

  Initiator, Target
Hadoop Properties None Specifies Hadoop environment properties for a user session. Properties are provided in a list. Use = between each property and its value (name=value, name=value, name=value), and a comma as a separator between properties, with or without a space after the comma.

For example:


If Hadoop Properties is not selected, the default Hadoop environment properties are used.


Keytab None Absolute path to the Kerberos keytab file. QueryGrid only uses the keytab file for authentication if a username and password is not provided.   Target
Link Buffer Count 4 Maximum number of write buffers available on a single channel at one time.
Link Buffer Count overrides the default internal fabric property shmDefaultNumMemoryBuffers.

Valid values are 2–16.


Initiator, Target
Link Buffer Size 1048576 Maximum size of the write buffers to allocate for row handling and message exchange.

Valid values are 73728–10485760 bytes.


Initiator, Target
Link Handshake Timeout 30000 Handshake and ACK timeout in milliseconds for the shared memory channel setup.

Valid values are 60000–86400000.

  Initiator, Target
Link Heartbeat Interval 3600000 Maximum interval in milliseconds for the heartbeat signal on a channel between the connector and the fabric instance, used for health check status. Tunable for diagnostic purposes only.
Set this interval greater than the Link Handshake Timeout.

Valid values are 60000–86400000.

  Initiator, Target
Number Executors None Unit of parallelism when data is exported or imported into Spark SQL.


Initiator, Target
Password None Password of the user or service account.   Target
Port 10016 Valid values for the Spark Connector are 1026–65535.   Target
Queue Name None Name of the queue that submits Spark jobs. Spark application mode only.


Read Timeout 3600000 Number of milliseconds to wait to read between data packets when importing data messages.

Valid values are 300000–86400000.


Initiator, Target
Response Timeout 86400000 Number of milliseconds to wait for the final data exec response when all the data has been transferred.

Valid values are 1800000–172800000.


Initiator, Target
Server None Used to connect to the target database as part of the JDBC connection string. This is the IP address or DNS name of the target host.   Target
Spark Resource Manager YARN Resource Manager used by the Spark platform. Possible values are YARN and standalone.   Both
Spark Monitoring REST Servers localhost:8080 One or more Host/IP:Port combinations for the Spark Monitoring REST Servers.   Initiator
Spark Home Path /usr/hdp/current/spark2-client/ Filepath to the Spark home directory where the /jars sub-directory resides containing all the Spark library .jar files.   Target
Spark Execution Mechanism Spark Thrift Server Mechanism used by the target connector to submit queries to Spark. Possible values are Spark Thrift Server and Spark Application.   Target
SSL TrustStore Password None SSL truststore or keystore password for authentication on the Spark Thrift Server when SSL is enabled.

Not needed if the keys are stored in the Java truststore.

SSL TrustStore Path None SSL truststore or keystore path for authentication on the Spark Thrift Server when SSL is enabled.

Not needed if the keys are stored in the Java truststore.

Temporary Database Name Default Temporary database name for storing temporary tables and views.


Username Hive Name of the user. A username added for a connector or target connector link must be included in Allowed OS users.

Maximum length is 255 characters.

This NVP is saved in the Teradata QueryGrid Manager configuration and is required when the initiator does not support a mechanism to provide user credentials. The username is also used for connectivity diagnostic checks.

Write Timeout 3600000 Number of milliseconds to wait to write between data packets when exporting data messages.

Valid values are 300000–86400000.


Initiator, Target