16.10 - Alternate Query Investigation Methods - Teradata Database

Teradata Database Administration

Product
Teradata Database
Release Number
16.10
Release Date
April 2018
Content Type
Administration
Publication ID
B035-1093-161K
Language
English (United States)
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.