The most effective and proactive method to prevent poorly written queries, such as those causing product joins on large tables, from harming the system is to use a Teradata Active System Management (TASM) system filter. Filters are rules that evaluate queries before they execute. An administrator can configure a filter to specifically detect and reject queries that are estimated to cause a product join, thereby preventing them from ever running and consuming system resources. This directly addresses the client's need to "avoid the harm" caused by these specific queries.

A. Use the Query Spotlight Viewpoint portlet to deprioritize the queries.

This is a reactive, manual action taken on a query that is already running. Deprioritizing only slows the query down; it does not stop the resource-intensive product join from occurring.

B. Use the Flex Throttle option.

Flex Throttles manage the number of concurrent queries based on system health. They do not inspect the nature of individual queries and cannot prevent a specific type of query, like a product join, from running.

D. Use the Query Log Viewpoint portlet to identity and abort the harmful queries.

The Query Log portlet is for analyzing historical query data after execution. It cannot be used to identify or abort queries that are currently running; that is a function of other portlets like Query Spotlight.

1. Teradata Vantage™ Workload Management User Guide, Release 17.20, B035-1197-112K.

Section: Filters: "Filters provide a way to prevent queries from running on the system based on user, query characteristics, or both... For example, you can use filters to prevent queries that are known to be resource-intensive, such as those that result in product joins, or queries that are estimated to run for a long time." (This directly supports option C).

2. Teradata® Viewpoint User Guide, Release 17.20, B035-2206-112K.

Section: Query Spotlight: "Query Spotlight is a real-time query monitor... You can perform actions on sessions and queries, such as changing a workload, changing a priority, or aborting a request." (This confirms option A is a reactive measure for already-running queries).

Section: Query Log: "The Query Log portlet allows you to view historical data about queries that have run on your Teradata systems." (This confirms option D is for historical analysis, not real-time intervention).

3. Teradata Vantage™ Workload Management User Guide, Release 17.20, B035-1197-112K.

Section: Throttles: "Throttles limit the number of concurrent queries... Flex throttles provide a way to dynamically adjust the throttle limit based on system conditions." (This confirms option B is for concurrency management, not query-specific rejection).