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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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Adjusting Available Free Memory (UNIX MP-RAS)

To protect against UNIX MP-RAS panics and prevent wasting free memory, you can increase the values of the page parameters in /etc/conf/cf.d/stune. Higher pages enable the OS to start paging sooner and thus free up memory sooner. The stune parameters and recommended values are as follows:

Change this parameter. From default (pages) of. To (pages).
LOTSFREE 512 8192

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Chapter 12: Troubleshooting

Tools for Troubleshooting Client Connections

Change this parameter... From default (pages) of. To (pages).
DESFREE 256 4096
MINFREE 128 2048

For more information on other settings associated with memory on UNIX MP-RAS, see the following sections in Teradata RDBMS Performance Optimization:

"RedistBufSize Performance Field"

"Adjusting for Low Available Free Memory"

Resolving Join and PPI Memory Issues

If insufficient memory is reported by queries involving hash joins, multiple JIs, HIs, and/or partitioned tables, modify the appropriate fields in the DBS Control GDO as indicated below. (For detailed instructions on modifying the DBS Control GDO, see "DBS Control Utility" in Teradata RDBMS Utilities.)

IF the query .

THEN .

returns error 7550 (hash join aborted due to nonavailability of segments)

make sure the following fields are set to their recommended value and resubmit the query:

Field Use Value
HHTMemAlloc (performance field) Percentage of memory to be allocated, per query, to the hash subtable during hash join processing. Note: Do not try to disable hash joins by setting this field to 0 and do not set it to a value higher than 1. 1
SkewAllowance (performance field) Factor used to decide the size of each hash join partition. 75

contends for memory when using partitioned tables in join, merge spooling, or aggregation operations

try increasing the value of the PPICacheThrP performance field and resubmit the query. This field limits the percent of FS cache allocated during PPI operations. (For details, see "Controlling Memory Usage with PPICacheThrP" on page 2-33.)

To determine the most efficient percentage according to your applications and types of operations, see "PPICacheThrP" under "DBS Control Utility" in Teradata RDBMS Utilities.

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Teradata RDBMS Database Administration Chapter 12: Troubleshooting

Tools for Troubleshooting Client Connections

returns error 3710 or 3711 (parser memory exceeded)

depending on the problem, modify the values in the following fields of the DBS Control GDO and resubmit the query. (Also see "Memory Limitations Related to Partitioned Primary Indexes" in Teradata RDBMS SQL Reference, Volume 4.)

IF the PPI table . THEN .
does not have JIs or HIs set the MaxParseTreeSegs performance field to 2000. This field controls memory segments allocated to parser operations.
also has a hash index and/or more than set the following fields to the recommended values:
one join index Field Use Value
MaxParseTreeSegs (performance field) Controls memory segments allocated to parser operations. 2000
OptMaxGlobalJI (internal field) Note: Contact the TSC for assistance. Controls the number of join indexes considered for a query. (The DBS Control utility cannot display internal fields. Contact the TSC.) 8


I

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Diagnosing SSO Logon Errors (Windows 2000 only)

Diagnosing SSO Logon Errors (Windows 2000 only)

If you are administering a Windows 2000 site that supports SSO, a high incidence of rejected logons might indicate a mismatch among user expectations and the settings of the SSO field in the Gateway Control GDO and the DBS Control Record GDO.

For detailed instructions, see "Implementing Single Sign On (SSO) (Windows 2000 Only)" on page 6-25.

Mismatch of DBS and Gateway GDOs

Errors will occur if users submit logons with passwords when both the DBS and the Gateway GDOs are set to SS_ONLY (or when DBSCONTROLGDO is set to ON and GTWCONTROLGDO is set to ONLY). Both GDOs must be set to the same SSO values, and your clients should be aware of the required procedure.

Note: A DBSCONTROLGDO setting of SS_ONLY or SS_OFF overrides any gateway setting.

To reset the SSO value in the DBS Control GDO, use the DBW command:

set sso on/off/only

To reset SSO in the Gateway GDO to a matching value, use the gtwcontrol command with the -a option.

gtwcontrol -a on/off/only

Include the -g option if you use client groups:

gtwcontrol -g hostid -a on/off/only

where hostid is the unique identifier you assigned to a client group. (For details, see "Logon Control" in Teradata RDBMS Security Administration.)

Non-Unique Usernames

Another setting that might cause SSO errors is the Append Domain Name field in the Gateway Control GDO. Attempts to log on will fail when:

A username cannot be recognized as unique across all domains in the network. (To guarantee uniqueness, you can append your usernames with domain names; see "CREATE USER and Logon Security" on page 5-6.)
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