2.06 - Presto Connector and Link Properties - Teradata QueryGrid

Teradata® QueryGrid™ Installation and User Guide

Teradata QueryGrid
Release Number
September 2018
English (United States)
Last Update
When you create links and associated properties in the QueryGrid portlet, you are creating Configuration Name Value Pairs (NVP). NVPs do 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 Presto are mapped to CLOB and BLOB by default. Unselect this option to map the STRING and BINARY columns to VARCHAR and VARBYTE, respectively.


Authentication Mechanism None Indicates the authentication mechanism used on the target data source.

Valid values are None, Kerberos, and LDAP.

This is a required setting.

Catalog Name hive Name of the catalog for the Presto connector.


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.

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-Presto link and is used by the target Presto 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 if less than the actual column size.

Valid values are 1–1048544000 characters.

This is for a Teradata-to-Presto link and is used by the target Presto connector and is applicable when the initiating Teradata Database does not support the CLOB data type 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 None Logging level for the connector or link properties. User level log settings can be explicitly set through the add or edit link page in the QueryGrid portlet.

This setting applies to both the initiating and target connector. The logging level for the initiator connector in the link, however, takes precedence if they are set differently.

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

  Initiator, Target
Explain Kind None Defines the flavor of the explain for the EXPLAIN SQL statement for a remote Presto query.

Valid values are logical or distributed.


Keytab None Absolute path to the Kerberos keytab file. QueryGrid only uses it for authentication if the user does not provide a username and password.   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 4–8.


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

Valid values are 73728–10240000 bytes.


Link Handshake Timeout 30000 Handshake timeout in milliseconds for the link channel setup.

Valid values are 5000–300000.

  Initiator, Target
Link Heartbeat Interval 60000 Maximum interval in milliseconds for the heartbeat signal on a channel between the connector and the fabric instance, used for health check status.
This interval should be greater than Link Handshake Timeout.

Valid values are 5000–300000.

  Initiator, Target
Password None User password.

Maximum length is 255 characters.

Port None Typically set to 8080.

This is a required setting.

Valid values are 1026–65535. The default value can be overridden.

Presto Reader Task Concurrency 8 Number of parallel concurrent readers in Presto per worker per query.


Presto Writer Count 8 Number of parallel writers in Presto or concurrent writer threads per worker per query.


Read Timeout 300000 Number of milliseconds to wait to read between data packets when importing data messages.


Initiator, Target
Realm None Kerberos realm.   Target
Response Timeout 1800000 Number of milliseconds to wait for the final data exec response when all the data has been transferred.


Initiator, Target
Schema Name default Name of the schema used for the Presto connector.


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
SSL Trust or Key Store Password None SSL truststore or keystore password for LDAP or Kerberos authentication on Presto.   Target
SSL Trust or Key Store Path None SSL truststore or keystore path for LDAP or Kerberos authentication on Presto.   Target
Temporary Database Name None Specified database name for creating temporary tables/views.

If you do not provide a database name in this property, QueryGrid creates the temporary view in the default database assigned to the user.


Username Default username for the connector. Name of the user.

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 300000 Number of milliseconds to wait to write between data packets when exporting data messages.


Initiator, Target