Limitations | Hive | QueryGrid - Known Limitations (Hive-to-Teradata) - Teradata QueryGrid

QueryGridâ„¢ Installation and User Guide - 3.06

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
Lake
VMware
Product
Teradata QueryGrid
Release Number
3.06
Published
December 2024
ft:locale
en-US
ft:lastEdition
2024-12-07
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ndp1726122159943.ditamap
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dita:id
lxg1591800469257
Product Category
Analytical Ecosystem
The following limitations affect use of Hive-to-Teradata links with QueryGrid:
  • Transaction semantics between systems is not supported.
  • Import of temporal tables is not supported.
  • QueryGrid does not collect query metrics (such as CPU usage) for remote Teradata queries.
  • Date literals used in WHERE clauses are not converted to the time zone of the remote system if the remote system time zone is different from the initiator system time zone.
  • The maximum size supported for BLOB and CLOB is less than 2GB (2,097,088,000).The maximum size of VARCHAR is 64k.
  • The temporary database name, NVP, is not supported on Teradata Database version 15.10.
  • The Foreign Function Execution (FFE) feature is not supported for the Hive target connector.
  • After data has been exported and committed to a remote system, any subsequent errors or aborts on the local system do not roll back the remote request.
  • The following Hive speculative properties are not supported and are disabled by default, unless the Support Hive Task Retries parameter is set to True:
    • mapreduce.map.speculative=false
    • mapreduce.reduce.speculative=false
    • hive.mapred.reduce.tasks.speculative.execution=false
    • tez.am.speculation.enabled=false
  • When using the Hive initiator:
    • For HDP, export is supported for Hive-on-Tez (Hive Execution Engine property = Tez) on HDP 3.0.1 or later only
    • Export is not supported for Hive-on-Spark (Hive Execution Engine property = Spark)
    • The target server returns all columns and the initiator server processes any column projection
    • The target server does not return query and plan data when using the Explain command
    • The target server returns all columns when using the Count command; these then aggregate on the initiator server
    • Sub-queries
  • If Hive is upgraded or the location of standard Hive JARs are changed, a tdqg-node restart is required.
  • The default for Timestamp precision is nine (9); QueryGrid truncates data with more than six decimal places when using Hive-to-Teradata links.
  • Date literals used in WHERE clauses are not converted to the time zone of the remote system if the remote system time zone is different from the initiator system time zone.
  • UTF-16 supplementary characters longer than 2 bytes in a table cause data truncation
  • IMPORT is not supported on the VARCHAR, STRING, and CHAR columns of the Hive table if the table character set is something other than Latin or UTF-16.
  • Condition pushdown of the LIMIT clause is not supported.
  • When running a SELECT query with UNION ALL in a Hive-to-Teradata connection, if the same target table is used among multiple select statements, you must create a unique external table name for each SELECT statement.