Alternate Query Investigation Methods - Teradata Database

Teradata Database Administration

Product
Teradata Database
Release Number
15.10
Language
English (United States)
Last Update
2018-10-06
Product Category
Software

Alternate Query Investigation Methods

 

Problem

Action

If the system is CPU-bound or disk-bound, or the processing is skewed.

  • Look at physical resource utilization:
  • Use Teradata Viewpoint. Monitor physical resources to view CPU/disk usage by node. Monitor virtual resources to view CPU/disk usage by vproc.
  • Look at DBC.ResusageSpma to view CPU, disk, and BYNET usage.
  • Look at workload utilization:
  • Use DBQL to find the user with the skewed processing.

  • Look at data distribution:
  • Use DBC.TableSizeV to identify tables with skewed data distribution.

    If the processing is skewed, identify the user.

  • Use Teradata Viewpoint.
  • Check DBC.SessionInfoV or run Query Session to identify the current user.
  • Check DBC.LogOnOffV to view historical users.
  • Check DBC.AMPUsage to identify the heavy resource user.
  • Check DBC.DiskSpaceV to identify large spool user.
  • If the processing is skewed, get information on the problematic query.

  • To identify the query, ask the user or check query log.
  • Run EXPLAIN on the query to determine if a bad join plan exists. Look for unexpected product joins. Verify that large tables are not joined before small tables. Look for estimates that are too high or too low.