Gathering optimizer statistics for upgrading oracle database. Problem is its taking more than 2 hours to finish gathering stats. What type of stats to gather bonus script dba paradise. Types for the minimum and maximum values and histogram endpoints include. In oracle 10g collecting of data dictionary statistics is.
By running these scripts before performing the actual database. Why sometimes gather stats runs for longer time than normal. Gather statistics on some oracle tables take a long time. You are looking for the methods to identify if these. Fixed objects statistics and why they are important. Beginning with oracle database 10g, oracle recommends you compute statistics for dictionary tables also. When it comes to statistics within your oracle database, information is power.
To decrease the amount of downtime, gather statistics. Oracle database automatically gathers fixed object statistics as part of automated statistics gathering if they have not been previously collected. To fine tune system statistics for the workload use start and stop or interval options. The majority of these questions can be summarized into two topics.
Oracle recommends gathering dictionary statistics after upgrade. That saying translates a lot of different ways but the overall idea is that the more you know about someone or something, the more effective you can be working with that someone or something. If you clone or relocate a pdb, then of course the statistics will not require special treatment assuming they are being maintained. Oracle database 10g is a big departure from previous releases of oracle insofar as oracle recommends that you analyze the data dictionary.
These tables have a record count ranging from 2 million records to 9 million records. A pdb has a dictionary and the auto gather stats job will refresh the dict stats as well. Maintaining statistics on large partitioned tables. This article will show you how to identify the last analyze date for system, oracle dictionary and fixed objects statistics. Oracle implicitly determines which objects need new statistics, and determines how to gather those statistics.
If you already have a wellestablished, manual statistics gathering procedure then you might prefer to use that instead. Sometimes its great to reinvent hot water and discover that a nice functionality is there since oracle 10g. Which has the higher priority in your organization. Of course this is warehouse with thousends of tables and hundreds of thousends partitions but even that i think we can get better performance. The database stores optimizer statistics in the data dictionary. System stats where introduced with oracle 9i, and contain information about the system hardware, such as cpu speed and io performance. Oracle gathers statistics on all database objects automatically and maintains those. Statistics improvements oracle database 11g release 2 11. Steps to upgrade oracle database from 10g to 11g alok. Managing automatic optimizer statistics collection or gathering statistics manually. The point is we want to keep it as standard as possible for new builds, upgrades and migrations as possible, but in the meantime are flexible enough to go ondemand changes in statistics gathring like addressing special needs on skipping stats. I remember an interesting discussion during oracle openworld 2009 in the thirsty bear pub in san francisco. Or you can use brconnect to collect oracle dictionary statistics as follows. How to identify the last analyzed date for system, oracle.
Oracle 11g gather statistics params raadinoracle dba. Workload statistics, introduced in oracle 9i, gather single and multiblock read times. Taking statistics and have them updated is a very important task on most oracle databases, the cbo cost based optimizer evaluates the cost of several execution paths, this cost is mainly based on physical and logical disk io, cpu use and network io, if our stats are not being taken or arent updated there is a possibility for the cbo to take a wrong decision. Let auto stats gather dictionary stats for you too and this is a continuous process rather than onetime operation. Oracle recommends using the most recent timezone data. Oracle database performance tuning guide for more information about managing optimizer statistics. Oracle isv migration center upgrade to oracle database 11g. Fixed table automatic statistic gathering in 12c blog. How to restore statistics and view statistics history.
Looking for a website, and resources, dedicated solely to. Gathering dictionary statistics after upgrading oracle docs. By running these scripts prior to performing the actual database upgrade, you. Concurrent processing how to gather statistics on oracle applications release 11i andor release 12 concurrent process,temp tables, manually. Library note which has the higher priority in your organization. From oracle database 12c release 1 the automatic statistics gathering job will gather statistics for fixed tables that have missing stats. With oracle 10g, the gathering of statistics has become automated. Since from oracle 10g the rulebased optimizer is no longer supported, in this. Since oracle 12c, table statistics are gathered automatically for some bulk operations.
But most dbas from the new school have already read 245051. So here is another post i keep mainly for my own reference, since i regularly need to gather new schema statistics. Steps to upgrade oracle database from 10g to 11gthis post covers step by step upgrade of oracle database from version 10g 10. Upgrading to oracle database 11g compatibility matrix minimum version of the database that can be directly upgraded to oracle 11g release 1 the following database version will require an indirect u. This appendix provides scripts that collect optimizer statistics for dictionary objects. In oracle 11g, that association does not seem to be present as the query returns.
Gathering fixed object statistics is valuable for database performance, because these statistics help the optimizer generate good execution plans, which can. In 10g statistics on the dictionary tables will be maintained via the automatic statistics gathering job run during the nightly maintenance window. How to check automatic statistics collection is scheduled on 10g. The job initiates a program of statistics gathering appropriate for the database in question. The statistics are stored in the data dictionary and can be exported from one database and imported into another.
Steps to upgrade oracle database from 10g to 11g steps to upgrade oracle database from 10g to 11g this post covers step by step upgrade of oracle database from version 10g 10. Upgrading to oracle database 11g persistent storage. Oracle data dictionary statistics tips expert oracle database tips by donald burleson december 8, 2015 question. Ask tom how to gather stats in 11g database oracle. We have gotten a lot of questions recently regarding how to gather and maintain optimizer statistics on large partitioned tables. You can monitor statistics gathering jobs using data dictionary views. This procedure gathers statistics for all system schemas, including sys and system, and other optional schemas, such as ctxsys and. See these notes on details for analyzing the fixed oracle tables. You can collect noworkload statistics in which oracle basically randomly reads the database data files to determine base statistics such as the average io seek. For further information, refer to my oracle support note 1585343. The statistics of interest to be viewed or modified can reside in the dictionary or in a table created in the users schema for this purpose. You need the new system privilege, analyze any dictionary, for this purpose. Oracle only gather stats on objects with stale statistics. This inconspicuous new feature called online statistics gathering for bulk loads is very practical for etl jobs in data warehouses.
Starting from oracle 10g, oracle introduced an automated task gathers statistics on all objects in the database that having stale or missing statistics, to check the status of that task. Oracle provides scripts that collect optimizer statistics for dictionary objects in oracle database. In particular, the automatic gathering of optimizer statistics. Only statistics stored in the dictionary have an impact on the costbased optimizer. Shows in this scenrio there are backup of stats that exists for scott. As per kba note 1817553 point 3, this is very important that the latest oracle dictionary and system statistics are collected to ensure the db is optimal. We cannot change the parameters of the above gather stats command as the application vendor insists as these. Hello tom i want to ask what should be the correct approach for a enterprise standard on statstics gathering for oracle dbs.