Performance Tuning :: Restart Database After Increase Db_cache_size?
Aug 23, 2012
SQL> show parameter sga
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 1152M
sga_target big integer 0
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in scenario above, the database do not using ASMM, and spfile If I wan to increase db_cache_size parameter, do i need to rebounce instance?
Step 1: Increased Physical Memory on one Node from 32 G to 48 G. Step 1 Impact : DB was running same as before Step 2 : Increased SGA from 12 G to 15 G. Step2 Impact : DB was running same as before for 1 day next day one reporting job was hanging. Step 3 : Increased DB_CACHE_SIZE from 5G to 7G. Step 3 Impact : Over all CPU Utilization was high and no effect on reporting job. Step 4 : Decreased DB_CACHE_SIZE from 7 G to 5 G. Step 4 Impact : CPU Utilization came down little bit but no effect on reporting job.
Now our main concern is why CPU Utilization is going high. Because same thing we did last time and we got positive results.
We have a table emp_details with 23772889 records. Our requirement is to increase few of the columns size in the table emp_details. We are following the below alter statement which is taking around 2 hours of time.
NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ undo_management string AUTO undo_retention integer 96000 undo_tablespace string undo
Following are the details in AWR report (00:00 til 01:00 of 21-Apr-2013) .... not thet the error was produced at 00:42
Undo Segment Summary DB/Inst: DBCPY/dbcpy01 Snaps: 18853-18854 -> Min/Max TR (mins) - Min and Max Tuned Retention (minutes) -> STO - Snapshot Too Old count, OOS - Out of Space count -> Undo segment block stats: -> uS - unexpired Stolen, your - unexpired Released, uU - unexpired reUsed
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Undo Advisor information taken 'now' is as following
SQL> select dbms_undo_adv.longest_query(sysdate-2,sysdate) from dual; DBMS_UNDO_ADV.LONGEST_QUERY(SYSDATE-2,SYSDATE) ---------------------------------------------- 379650 SQL> select dbms_undo_adv.required_retention from dual;
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In above situation what should be my first choice (assuming increasing space is not an issue) - increase undo tablespace or increase undo retention?
If latter is the choice then what should be the value? Because as I understand present 96000 value is taken as lower limit and because of auto tuning the actual value (TUNED_UNDORETENTION) being used was 345600 In that case shall I set it to something > max(maxquerylen) i.e 379,650 + X?Or I shall increase the undo tablespace size?
From Undo Advisor output it looks to me that even if I increase the undo retention to 379650 current undo size will be able to support it (may be at the expense of DMLs)Is that right?
Looking to understand the difference between instance tuning and database tuning.
What is the difference between these two tuning exercises? I understand that an instance is memory based structures (logical) where as database consists of physical structures.
However, how does one tune a database the physical structure? Does it have to do with file placements/block sizes etc. Would you agree that a lot of that is taken care by ASM now in 11g? What tools are required/available (third party as well as oracle supplied) for these types of tuning scenarios?
There is a simple way to increase the performance of a query by reducing the row-size of the table it hits. I used it in the past by dividing the table into smaller parts and querying respective smaller table in each query.
what is this method called ? just forgot the method and can't recall it. what this type of row-reduction optimization is called ?
Testing our 9i to 11g upgrade, we've imported the entire DB into the new machine.We've found that certain procedures are really suffering performance problems. BUT, we've also found, that if we check out a production copy of the procedure from our source code control, and reinstall it, the performance issue goes away. Just alter the procedure and recompiling does NOT work.
The new machine where the 11g database exists is slightly different than the source, but it's not like we have this problem with every procedure. It's only a couple.
any possible reason that we'd have to re-install a procedure to correct a performance problem?
One of my MOD_PLSQL based Oracle APEX Application is running on the web. I have almost 1000 web users to access the Application where at least 250-300 users are always on line. In Oracle EM web interface When run ADDM I see suggestions "Investigate the cause of SQL*Net more data to client" or something like this. and I am getting complains about poor server response. Here are my configuration of the system:
Database Server Host: DBServer (Oracle Database 10.2.0.3) HTTP Server Host: OraHTTP (Oracle Companion CD 10g)
DADS.conf HTTP Server configuration MOD_PLSQL database access for web clients.
How can I increase database connection performance?
insight into the overheads for mutally authenticated SSL for database connections? This is over a fast local network, to a RAC cluster, with DB firewall in front. There's always a large element of "it depends"
Information I'm interested in are things like latency for initial session setup and subsequent data transfer. Also the increase in network packet size, and the increase in CPU cost for the database server. I guess there is some implications for session memory usage as well.
I have one big database which I need to migrate to Oracle, because it rocks with big databases, instead of other databases and when I was made transfer software and all works great except one more think. During this process I found that Oracle normally fill log & undo table, and my question is how to migrate (or can I migrate) database to oracle without filling undo database (deactivate this process) and after that to put database to work normally, because I just need to transfer data as is and from that point Oracle goes on...
i am using 11.2.0.3 version of oracle. We have recently migrated to 11g, after 1 month of smooth and comparatively better performance, we are suddenly facing performance issues with our database and it got crashed twice within 5 days. even we didnt push any new code to our database in recent past, atleast after the 11G migration. And after getting feedback from the ORACLE corporation guys , they pointed out about the default database stats gathering job, which was eating most of the CPU, because of the default degree mentioned So it was running in 160 parallel threads causing resource starvation.so we reduce the degree of the stats gathering job to 8 .
But the database crashed again two days back, and rebooted within 3 mins to back to normal, even after this default degree changed to 8. This is happening due to any specific application related sql or anything else.
I am doing import and export of database.Before loading data i drop all the tables and import.Is there any issue if we do drop tables and import data frequently.
I understand that when data is read from the disk, I/O is done..And When computations are done then CPU is used..Then where the following equation fits?
we are using oracle 9i on AIX Server. When Customer were accessing the database, accidentally power was shut down. we restarted the Server,and Oracle database. all resumed successfully.
However while doing "Payments by the customer" it takes a lot of time to insert even a single payment record on database.The database is Live and our customer are very much frustrated,
We are just but new oracle 10g(10.1.2.0.2) Database and application server ( form and report server ).have installed application server on window server 2003.
it will running ,but it is used lots of memory.so the performance decrease when user increase.
I am facing a weird situation wherein the explain plan of same sql in SIT and PROD is different.In fact the explain plan is very costly in Prod.Also the DB version of both SIT and PROD is same.
Below is the sql and corresponding explain plan in Prod and SIT respectively.
Query: SELECT seq,CCN,ProcessorPart,root_item,comp_path,Item,comp_item,comp_item_type, lag(comp_item_type,1,'PART') over(PARTITION BY seq ORDER BY lvl)Nxt_comp_item_type,lvl,bom_qty, ROUND(CASE min(abs(bom_qty)) OVER (PARTITION BY seq ORDER BY lvl) WHEN 0 THEN 0 ELSE 1 END * EXP (SUM (LN (nullif(abs(bom_qty),0))) OVER (PARTITION BY seq ORDER BY lvl))) Ulti_qty, 'AMER'
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The tables referred in above query is small tables containing arnd 10k records.The above tables are partitioned on Region and not indexed.
I am not able to attribute why there is a huge change in Cost between SIT and Prod.Apparently the Job is going for 3-5 hours which used to get completed within 20mins in SIT.
We have database with multiple fields containing NULL values and in many queries we have NVL function which in turn is suppressing the index usage when in fact it is really essential (selectying very few rows from massive data) instead of creating lot of Function based indexes (NVL) or composite indexes with (nullable_column, constant) I am thinking of settting a default value for most of the fields In that regard I have some queries :
Which approach is better - setting default value for the fields or updating the fields with default value and modyfing inserts to take care of future data? Though altering table and modifing column to set default value looks better considering it will take care of data inserted in the future, it will invalidate the subroutines.I understand in 10g both statement will generate lot of undo (though in 11g, I heard things changed for setting default value of a column) How to take care of all the queries which are using the criteria 'where column1 IS NULL' or 'where column1 IS NOT NULL'. It will be really difficult task to manually change each and every occurrence of such condition even using user_source.
Finally for numeric values say for ID field which starts from 1 onwards 2,3,4 etc, we can set 0 as sensible default so that the performance is not affected.
Is there such precaution for varchar2 field purely from performance point of view?
I have a question regarding memory parameters in oracle database 9.2.0.8, especially sga_max_size and db_cache_size. Database server has 32G of ram. Oracle parameter on server shmmax is set to 16G. Is reasonable to set sga_max_size to the same value, and db_cache_size to 80% of that size?
By default the DBMS_STATS package runs once every 24 hours to collect statistics for database objects and Oracle collects new statistics when enough of the data (about 10%) has changed.
My question here is how to check the table has changed 10% in database?
As there was a database performance, we started to analyse the issue by running ADDM using below.
@?/rdbms/admin/addmrpt.sql.
The result of running ADD is below.
DETAILED ADDM REPORT FOR TASK 'TASK_64718' WITH ID 64718 Analysis Period: 10-APR-2012 from 06:00:15 to 07:00:22 Database ID/Instance: 324353546/1 Database/Instance Names: JACK/jack1 Host Name: fdsfggwe001 [code].....
There was no significant database activity to run the ADDM.The database's maintenance windows were active during 100% of the analysis period.The analysis of I/O performance is based on the default assumption that the average read time for one database block is 10000 micro-seconds. An explanation of the terminology used in this report is available when you run the report with the 'ALL' level of detail.
I support to get a handle on statistics collectionn in their data warehouses. It seems developers have created several ANALYZE TABLE jobs but the code for these is not stored as PLSQL in the database and thus it is problematic for statistics collection. Even if we collect stats that way we want, these jobs kick in and overlay the statistics we collect every day.
Is there a way to AUDIT ANALYZE TABLE? I can't find it anywhere.
Is there a way to globally turn of ANALYZE TABLE in a 9i database?
I just shutdown the database and it seems to take a while, don't know if it's stuck or just takes awhile. I try to restart it in another session and get this error:
'ORA-01012: not logged on'
1) Shutdown SQL> connect sys/Welcome1 as sysdba Connected. SQL> shutdown normal _
2) So I try to restart it as sysdba on another session and get this error Connected to an idle instance. SQL> startup ORA-01012: not logged on
For a one week, oracle database (v 9.0.1.0.0) is hanging frequently.I could't showdown/restart the database. After restart the server (RedHat), the database is opened without any problem.after 9 or 10 hours once again hanging. too large spaces are availble in my HardDisk.
