SCRIPT - to Set the 'SESSION_CACHED_CURSORS' and 'OPEN_CURSORS' Parameters(文档 ID 208857.1)

Abstract  SCRIPT -  to Tune the 'SESSION_CACHED_CURSORS' and  'OPEN_CURSORS' Parameters   Product Name, Product Version Oracle Server Enterprise Edition  Versions 8i, 9i, 10g and 11g.    Platform  GENERIC Date Created  24-Nov-2002   Instructions  Execution Environment:      SQL*Plus Access Privileges:      Requires user access to v$statname, v$sesstat, v$parameter,  Usage:      sqlplus <user>/<pw> @[SCRIPTFILE]  Instructions: PROOFREAD THIS SCRIPT BEFORE USING IT! Due to differences in the way text  editors, e-mail packages, and operating systems handle text formatting (spaces,  tabs, and carriage returns), this script may not be in an executable state when you first receive it. Check over the script to ensure that errors of this type are corrected.The script will produce an output file named [outputfile]. This file can be viewed in a browser or uploaded for support analysis.   Description  To allow the DBA/Analysts to check whether the sessions cursor cache or open cursors are really a constraint and then increase the parameter  session_cached_cursors or open_cursors accordingly. The Parameter SESSION_CACHED_CURSORS lets you specify the number of cursors to cache within an individual session. Repeated parse calls of the same SQL statement cause the session cursor for  that statement to be moved into the session cursor cache.  This script reports the setting of these parameters (at the system level) in the VALUE column and then the current maximum usage in any session as a percentage of these limits. If either of the Usage column figures approaches 100%, then the corresponding  parameter should normally be increased.  NOTE: Remember that the Parameter SESSION_CACHED_CURSORS can be changed dynamically at the session level. This means that if a session has increased its session cursor cache above the standard parameter setting, you could see percentages greater than 100%. If this happens you need to consider whether you want to use a higher value for all sessions or whether this 'special' session that is setting the higher value is an exception.   References  Note:1012049.6 Tuning Library Cache Latch Contention   Script  select   'session_cached_cursors'  parameter,   lpad(value, 5)  value,   decode(value, 0, '  n/a', to_char(100 * used / value, '990') || '%')  usage from   ( select       max(s.value)  used     from       v$statname  n,       v$sesstat  s     where       n.name = 'session cursor cache count' and       s.statistic# = n.statistic#   ),   ( select       value     from       v$parameter     where       name = 'session_cached_cursors'   ) union all select   'open_cursors',   lpad(value, 5),   to_char(100 * used / value,  '990') || '%' from   ( select       max(sum(s.value))  used     from       v$statname  n,       v$sesstat  s     where       n.name in ('opened cursors current') and       s.statistic# = n.statistic#     group by       s.sid   ),   ( select       value     from       v$parameter     where       name = 'open_cursors'   ) / Sample Output   PARAMETER               VALUE     USAGE  ----------------------  --------  ---------  session_cached_cursors         0        n/a  open_cursors                 300         1%    Disclaimer  EXCEPT WHERE EXPRESSLY PROVIDED OTHERWISE, THE INFORMATION, SOFTWARE, PROVIDED ON AN "AS IS" AND "AS AVAILABLE" BASIS. ORACLE EXPRESSLY DISCLAIMS ALL WARRANTIES OF ANY KIND, WHETHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. ORACLE MAKES NO WARRANTY THAT: (A) THE RESULTS THAT MAY BE OBTAINED FROM THE USE OF THE SOFTWARE WILL BE ACCURATE OR RELIABLE; OR (B) THE INFORMATION, OR OTHER MATERIAL OBTAINED WILL MEET YOUR EXPECTATIONS. ANY CONTENT, MATERIALS, INFORMATION OR SOFTWARE DOWNLOADED OR OTHERWISE OBTAINED IS DONE AT YOUR OWN DISCRETION AND RISK. ORACLE SHALL HAVE NO RESPONSIBILITY FOR ANY DAMAGE TO YOUR COMPUTER SYSTEM OR LOSS OF DATA THAT RESULTS FROM THE DOWNLOAD OF ANY CONTENT, MATERIALS, INFORMATION OR SOFTWARE. ORACLE RESERVES THE RIGHT TO MAKE CHANGES OR UPDATES TO THE SOFTWARE AT ANY TIME WITHOUT NOTICE.   Limitation of Liability  IN NO EVENT SHALL ORACLE BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES, OR DAMAGES FOR LOSS OF PROFITS, REVENUE, DATA OR USE, INCURRED BY YOU OR ANY THIRD PARTY, WHETHER IN AN ACTION IN CONTRACT OR TORT, ARISING FROM YOUR ACCESS TO, OR USE OF, THE SOFTWARE. SOME JURISDICTIONS DO NOT ALLOW THE LIMITATION OR EXCLUSION OF LIABILITY. ACCORDINGLY, SOME OF THE ABOVE LIMITATIONS MAY NOT APPLY TO YOU.

REFERENCES

NOTE:1012049.6 - Tuning Library Cache Latch Contention (8i and below)
NOTE:214179.1 - SYSTEMS: Standalone Script Template
NOTE:430473.1 - ORA-4031 Common Analysis/Diagnostic Scripts [Video]

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• Oracle Database Products > Oracle Database > Oracle Database > Oracle Database - Personal Edition > RDBMS > Database Level Performance Issues (not SQL Tuning)
• Oracle Database Products > Oracle Database > Oracle Database > Oracle Database - Enterprise Edition > RDBMS > Database Level Performance Issues (not SQL Tuning)
• Oracle Database Products > Oracle Database > Oracle Database > Oracle Database - Standard Edition > Generic RDBMS > Database Level Performance Issues (not SQL Tuning)

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DATA_COLLECT; QTUNE