2.10 - RTO Process - Teradata QueryGrid

Teradata® QueryGrid™ Installation and User Guide

prodname
Teradata QueryGrid
vrm_release
2.10
created_date
September 2019
category
Administration
Configuration
Installation
User Guide
featnum
B035-5991-099K
When a query is sent from the Teradata Database to a remote data source, and a push profile is used, the following occurs:
  1. The operation is sent to the remote data source.
    Statistics are collected. The statistics and push profile settings determine whether the operation is performed on the remote data source.
  2. A temporary table is created on the remote data source and the following scenarios apply:
    • If delayed fetch is enabled and chosen based on static statistics, dynamic statistics are collected for the temporary table. The statistics determine whether a remote join or local join is performed on the temporary table.
    • If a remote join is chosen (with or without delayed fetch), the temporary table is exported for a local join.
  3. Statistics about the row count and byte count of the temporary table are collected and sent to the Teradata Database optimizer for analysis.
  4. If the counts are at or below the delayed fetch threshold specified in the push profile, the query result (the temporary table) is sent to the Teradata Database.
  5. If the byte count is greater than the delayed fetch threshold, the dynamic statistics that were collected are sent to the optimizer. The optimizer then decides whether a local join or remote join is performed.
    • If a local join is chosen, the temporary table is brought back in a separate execution phase.
    • If a remote join is chosen, the local table is exported, joined with the temporary table on the remote system, then brought back to the local system.