1
vote
2answers
68 views

Oracle becomes too slow after system crash

I am using Oracle 11.2 as a database for my application. For this purpose I should import my data (around 100m records) to this database. For this purpose I used SQL Developer. Unfortunately at the ...
1
vote
2answers
41 views

Oracle result cache behaviour

Oracle by default caching the query results and function results(Buffer cache). I have noticed this with AutoTrace utility, where the physical reads are huge on first execution, but from next ...
0
votes
1answer
29 views

HOW does ROWNUM work with this “optimization”

I'm trying to optimize a query in which I have some requirements where I need to be able to arbitrarily select a row ROWX from a query. Why is it that SELECT XML_DATA FROM (Select ROWNUM AS ...
1
vote
1answer
30 views

Oracle Compatible Parameter to set

Is there any difference in setting the Compatible Parameter to 11.2.0.0 vs 11.2.0.4 ? Are there any advantages / dis-advantages ?
0
votes
0answers
92 views

index usages on table with recursive relationship

we are working on a project that uses jpa and oracle. In this project we have a table with a recursive relation: Create table alarm ( id varchar2(200), ... alarmcode varchar2(50), parent_id ...
0
votes
1answer
38 views

Access and filter in oracle plan

I came to a execution plan where oracle choose to access the index but instead of using the columns as predicate it only filter by them. My question is what are the reasons that can cause that(all ...
0
votes
1answer
56 views

How to interpret undo statistics in Oracle AWR report?

How can I use undo statistics in oracle AWR report for tuning Oracle? which indicators are important to identify that size of undo segments needs to be increased?
0
votes
1answer
42 views

Oracle 11g max login fail attempts workaround

My problem with database starts with situation where I cant really modify anything in database. My project specialist has limited time to help me. Here is the thing: My user in Oracle database has ...
0
votes
0answers
44 views

Explain difference between insert as select and select

Can someone explain why there is plan difference? Same query, same time the explain plan taken. I understand what happen (different order of getting the data) and how to fix it(move to forall insert ...
2
votes
1answer
61 views

In Oracle AWR report how to use “Latch statistics” section in analysis

Latch statistics in AWR report contain following sections 1.Latch Activity 2.Latch Sleep Breakdown 3.Latch Miss Sources 4.Parent Latch Statistics 5.Child Latch Statistics How can I use these ...
0
votes
1answer
99 views

performance difference between < and <=

I remember that there is a performance issue with SQLs that use "<" against "<=" because of statistics and/or histograms and/or the data itself, but I dont remember exactly the issue. I know ...
0
votes
1answer
126 views

How index work in oracle? [duplicate]

I want to understand : How index work in oracle. How they are stored in the disk. How they increase the efficiency of a query? By third point I means how Index contribute to the efficiency of ...
0
votes
2answers
72 views

Tips on using SQL access advisor in Oracle

Please share how to use oracle SQL access adviser for single or multiple queries. you can assume that we know the sql ids for the queries we are interested in.
1
vote
1answer
72 views

What useful information can I get from ASH report which I cannot get from AWR report?

What useful information can I get from ASH report which I cannot get from AWR report? What are the common scenarios in which its better to get information from ASH than from AWR?
0
votes
0answers
29 views

Slow exporting SAP Data Services to MySQL (Oracle is faster)

We've a MySQL 5.1 server and we are trying to import data from SAP Data Services from another server. It works but it takes 3h! We tried to setup an Oracle XE server to test the same operation and it ...
2
votes
1answer
51 views

Does Windows Server File Compression slow Oracle DB performance?

I'm starting a new a new contract and I get to troubleshoot their Oracle instance... I'm more apps and sql, but I'll be trying to figure out their crashes and slow performance. Go figure. I can ...
0
votes
2answers
133 views

oracle active sessions waiting for scheduler

Load on my 11g RAC looks like this: and I don't understand how to get insight into what this "scheduler" wait class is. It seems like "scheduler" that it refers to is the process that runs ...
1
vote
1answer
127 views

Internal query on CDEF$ and CON$ very CPU bound

I am checking an application (Infor ERP LN) that loads a lot of data into an oracle 10.2 database. While checking one of the user sessions with SQL_TRACE and its output with tkprof, I found that the ...
1
vote
2answers
66 views

distinguish single-block vs multi-block reads in Oracle explain plan

If I am looking at a query plan in Oracle 11g, is there any way I can tell which operations will result in single-block reads and which will result in multi-block?
1
vote
3answers
131 views

Oracle: terrible execution times from virtual application server

I've been provided with an Oracle VM linux box playing host to an Oracle 11g installation. I've also been provided with an Oracle VM Windows Server 2008 64-bit box acting as an application server. ...
0
votes
0answers
95 views

Oracle - How can I improve this query?

We have performance problems with some queries. We always use the rank() function to get the latest entries with a status. The question is, how to speed up things. CREATE TABLE PAYMENT ( CLIENT ...
3
votes
1answer
191 views

What is Required to use Oracle Performance Manager to monitor SQL Server?

I am working with a customer who has several SQL Server and Oracle DBMS server instances. My customer would like to setup up performance data collection, monitoring and alerting for all of their ...
0
votes
2answers
743 views

Oracle query is slower the second time

I have a general question about something I'm seeing in performance tuning in Oracle. I have a query that I'm testing. It's too big and complex for me to provide a simple example, sorry! (I tried ...
1
vote
1answer
88 views

A query executed in a backup of a database is performing better than if executed in the original database

We have two databases with the same data, let's call it Database A which is the original and Database B which is the backup from Database A. A query is performing much better in Database B for example ...
1
vote
0answers
74 views

Oracle specifying join order hint

Oracle 2 node RAC 11G R2 I have a query (this is a simplified version, but still exhibits the same issue as the larger query) that looks like this: SELECT t1.trip_id, t1.origin, ...
1
vote
1answer
86 views

How to -create- performance issues? - oracle [closed]

I want to dedicate some time to learn more about performance and tuning issues. I assign for that a clean DB. I want to know how can I load into it some data and performance-problem queries/DML/DDL? ...
0
votes
1answer
212 views

Oracle intermittent performance problem

I have some complex queries that are usually fast (< 1 sec), but occasionally slow (> 10 sec, even minutes). How do I track this down or identify what condition is causing it? One theory was ...
1
vote
1answer
316 views

How to partition an Oracle table with 65 million rows?

The table that needs partitioning contains a list of Components and their Values. So one table is tblComponents. Another is tblFields. Then this table, tblValues, contains the values of the ...
0
votes
2answers
1k views

Index for date column for range query in Oracle?

We have a lot: select count(*) from TBL where XDATE between ? and ? and FLD = ?; We expect to boost performance by tuning index on XDATE column (which have DATE type). What type of indexes more ...
1
vote
1answer
176 views

How to keep an Oracle 11g instance lean?

As a Mac user I run a local Oracle Enterprise Linux (OEL) Developer Day VM that houses an Oracle 11g instance for development/unit testing. I frequently refresh the data in the schemas (sometimes ...
0
votes
1answer
159 views

Can we create a table in specific datafile - Oracle 11g R2?

I am buying a new server than has two HDs: 300 GB with 15000 rpm. 600 GB with 10000 rpm. I am thinking to allocate the datafiles in both hard disks. and put the less used tables in the data files ...
0
votes
1answer
442 views

Changing the SGA and/or PGA in Oracle 11g affects the performance of the queries?

I am making a practice for school where one of the questions is if changing the SGA/PGA size would affect the queries performance and in what sense. I have been looking around for how to do that and ...
5
votes
1answer
159 views

Sudden increase in log_file_sync waits

I'm on Oracle 11gR2 with a 2 node RAC system. It's shared fiber storage to an EMC Clariion. Last friday things went bad..fast. All of the sudden processes that normally ran fine for years became ...
1
vote
0answers
161 views

Performance Hit when upgrading to Oracle 11gr2

I am experiencing the same symptoms as noted in this question which was closed and does not have a satisfactory answer. Original Question We've recently upgraded from Oracle 10gR2 (10.2.0.4 ) to ...
0
votes
1answer
126 views

Efficient way to perform approximated search?

I have to perform a join between table_a and table_b, using three fields as key being one of them the date of the event, say, both tables have id1, id2 and evnt_time for eache record. As it happens ...
0
votes
0answers
224 views

Temporarly disable cache in oracle 11g

I want to disable the caching for my session in oracle 11g to see how long a query takes. Is this possible or is there a better way for meassuring the time a query takes to run?
1
vote
1answer
3k views

What is the best way to insert a XML input to an oracle table in stored procedure?

I want to write a stored procedure which has a XML input (clob type) and inserts the data to a table. my XML structure is something like this: <rowset> <row> ...
3
votes
1answer
2k views

Oracle insert through dblink performance issue

I'm trying to do an insert as select to a table via dblink. The query looks like this: Insert into MARS_SUPERVISORS_PUB@EDHPUB select {...} from edhper a, edhper b where ...
4
votes
1answer
126 views

Oracle BLOB store performance

LOBs in Oracle are stored in-row when they are less than 4K in size and out-of-row otherwise. I'm wondering how do SECUREFILE storage options COMPRESS and ENABLE STORAGE IN ROW work? I have a lot of ...
0
votes
0answers
56 views

Database too slow after CHARSET Conversion

I have an Oracle database which runs on version 9.0.1 with WE8859P1 charset and i'm trying to migrate it to the version 9.2i which has the WE8MSWIN1252 charset. The conversion is made without any ...
3
votes
1answer
6k views

What queries is Oracle executing, how frequently, and time-taken?

I have a (Java) web-application, that of course executes many queries (selects, inserts, updates, deletes) to the Oracle Database. I want to find out the following for last 7 days: SQLQuery ...
5
votes
1answer
624 views

Oracle aggregate functions slows query down massively

I have a table with ~12M rows of data in it. Here is the table structure: SYSTEM_ID BATCH_ID MEASUREMENT_INDEX, PARAMETER_ONE, PARAMETER_TWO The primary key is made up of the first three columns. I ...
1
vote
1answer
1k views

Oracle 11g: “With Clause” very slow

I have written a query utilizing Oracle's with clause. I have identified one particular with clause in a larger query to be really, really slow. Here are three versions of the same query, they all ...
3
votes
2answers
593 views

Increase Oracle buffer cache gets slower

So we're contemplating increasing our Oracle 11gR2 buffer cache. They said they tried it in the past and things appeared to get worse - so they undid the change. They, however, have no idea why ...
2
votes
0answers
850 views

Oracle high Paging Faults

What are the reasons that lead to terrible high Paging faults. The following is the topas information and background about the Environment. OS: AIX 6.1 Softwares: Oracle 11gR2 Paging Space:30720 ...
0
votes
0answers
491 views

Oracle 10g - Sudden change in execution time for specific query

After the DBAs fiddled with some parameters in our Oracle 10g Production Environment, most queries became a little faster. But a single query (a quite complex one) became dramaticaly slower - it went ...
1
vote
2answers
398 views

How to isolate general Oracle 10g issues through SQL

Background: I've been working on a performance analysis on a system with major performance issues on a Oracle 10g server. Much of the SQL is badly written, or at least not written with performance in ...
2
votes
3answers
139 views

How can I identify and fix bottlenecks in an Oracle11gR2 import

I've recently been tasked with moving our Oracle 11g database from a linux CentOS desktop to a windows 2008 server. Given I've not done much behind the scenes stuff with oracle before I'm a bit out of ...
4
votes
2answers
1k views

Hibernate Query Running Slow

I am currently facing a problem with a slow running Hibernate query that is being kicked off from a Java program. It is making a call to Oracle 11g at the back end. This query is taking anything from ...
3
votes
3answers
296 views

Why does the query cost change so much and how to prevent it

The query causing me the issue is too big, but the piece that seems to be the core is quite simple, I will try to go with that: The query has an structure like: SELECT ... a lot of stuff ... ...