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Teradata RDBMS Database Administration - NCR

NCR Teradata RDBMS Database Administration - NCR , 2004. - 616 p.
Download (direct link): teradatadatabaseadmin2004.pdf
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Disk and AMP CPU usage

Use ResUsage reports to determine whether:

Disk I/O counts seem too high. You may be able to reduce I/Os by modifying the Cylinder Read default values. For details, see "Managing I/O with Cylinder Read" on page 15-2.

High and low disk and AMP CPU usage values are the same or different. The action you take depends on your findings, as follows:

IF disk and AMP CPU values are . THEN .
different resource utilization is skewed. There may be a system problem in one of the AMPs or PEs, or uneven data distribution. Check the hardware and/or applications as follows: For uneven data distribution, discuss improving primary index uniqueness with operations and/or application designers. For an AMP or PE problem, see "Tools for Troubleshooting Hardware" on page 12-10.
the same There may be a problem with the client connection. For help, see "Tools for Troubleshooting Client Connections" on page 12-8. You may need to add AMPs, PEs, disks, and/or nodes for more capacity. For help, see "Solving Bottlenecks by Expanding Your Teradata RDBMS Configuration" on page 12-28.

12 - 26

Teradata RDBMS Database Administration 12 - 23 Chapter 12: Troubleshooting

Solving PPI and RI Validation Errors

Solving PPI and RI Validation Errors

You can use the following procedures and tools to detect and correct errors in tables that use partitioning and referencing. (For details, see "Benefits of a Using a Partitioned Primary Index (PPI)" on page 2-25 and "Using Referential Integrity" on page 7-7.)

IF you want to ... THEN .
correct a partitioning expression that is causing transaction rollbacks due to an evaluation error (such as divide by zero) do one of the following: Change the partitioning expression Delete the rows causing the problem Remove partitioning from the table Drop the table
find invalid table states and/or internal structures run the CheckTable utility LEVEL 3 command.
regenerate only the headers in a table with a PPI use the ALTER TABLE ... REVALIDATE PRIMARY INDEX statement
for a table with a PPI: Regenerate table headers Re-evaluate partition expressions Recalculate row hash values Move rows to proper AMPs and partitions Update any SI, JI, and HI defined for the table use the ALTER TABLE . REVALIDATE PRIMARY INDEX null_partition_handler WITH DELETE / INSERT [INTO] statement. WITH DELETE deletes any rows with a partition number outside the range 1-65535. WITH INSERT [INTO] deletes any rows with a partition number outside the valid range and inserts them into save_table. Note: REVALIDATE changes the table version.
reset the state of RI tables after an ARC RESTORE operation run the ARC utility REVALIDATE REFERENCES FOR command.
find corrupt rows after running an update or delete operation using WITH NO CHECK OPTION on tables with RI constraints submit the RI Validation Query, structured as: SELECT DISTINCT childtablename.* FROM childtablename,parenttablename WHERE childtablename.fkcol NOT IN (SELECT pkcol FROM parenttablename) AND childtablename.fkcol IS NOT NULL; This query reports every row in the Child table with an FK value that does not have a matching PK value. (FK nulls are excluded because it is not possible to determine the values they represent.)
purify a Child table for which corrupt rows were reported by the RI Validation Query Delete from the Child table any reported rows as soon as possible in order to maintain the integrity of your database.

Teradata RDBMS Database Administration

12 - 27 Chapter 12: Troubleshooting

Solving Bottlenecks by Expanding Your Teradata RDBMS Configuration

Solving Bottlenecks by Expanding Your Teradata RDBMS Configuration

System saturation and bottleneck identification are interrelated. When your Teradata RDBMS is saturated, the bottleneck is usually some key resource, such as a CPU or disk. Use the information obtained from performance monitoring, resource usage, and query capture and process tracking tools to find the cause of repeated bottlenecks.

If a resource has been a bottleneck consistently during peak utilization periods and you have determined that your database design, data modeling, and query structures are efficient, consider expanding your Teradata configuration to improve performance.

Expansion involves adding any combination of disk arrays, memory, vprocs, or nodes (with BYNETs), and then running the pdeconfig or Parallel Upgrade Tool (PUT) and Configuration and Reconfiguration utilities.

The Reconfiguration utility can provide an estimate of the duration of outage based on parameters you supply interactively. (For an overview of the utilities and a summary of procedures, see "Viewing or Modifying the Teradata RDBMS Configuration" on page A-13.)

Note: Make sure your applications are scalable and can take best advantage of the expansion. For guidelines, see "Scaling Your Applications" on page 12-32.

Determining Resource Needs

When planning expansion, you need to determine whether your configuration needs more memory, a more powerful or additional processors, more nodes, more disks, more disk array controllers, or additional options for OLTP environments.
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