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Cache fusion potentially expose your database to many contention problem on resources. Typical contentions are: Read/Read contention – a false problem as a shared storage can be deal this contention without GCS intervention Write/Read contention – solved using consistent read technology Write/Write contention – contention addresses to Cache Fusion technology solved shipping needed block across [...]
I’ve hit this bug in my environments. See below: SQL> create sequence ste_seq 2 start with 1 3 increment by 1 4 nocache 5 noorder; Sequence created. SQL> select ste_seq.nextval from dual; NEXTVAL ———- 1 SQL> drop sequence ste_seq; Sequence dropped. Now, this is a normal sequence creation, use and drop. Now you sure expect [...]
A core component of Oracle RAC Database is the Cache Fusion. Cache Fusion should not be intended as a merged buffer cache across all RAC instances. This is what many people thinks and what you may see but the reality is that each node has a private buffer cache and thought Cache Fusion blocks needed [...]
Does column position affect performance? The answer is Yes, definitely. Even if many people does not think so or worse they ignore it. Let’s explain in few words how Oracle stores row for a table. For each row you have a row header that contains usually general information about the data as block address, and type [...]
OPAQUE_TRANSFOR comes as undocumented hint you can usually see in a data warehouse environment. Oracle rewrite query INSERT INTO..SELECT or CREATE TABLE..AS every time you refer to a remote instance using DBLink. OPAQUE_TRANSFORM appears every time query is distributed and involves the SELECT part from remote database. SQL> insert into t1 select * from t1@lab11r2 [...]
These days I’ve dealt with a big problem. Consider an infrastructure where you have some ESX4 connected with 4 paths to a MetroCluster NetApp 3040. For some not really known reasons out storage came out with the following error: Wed Feb 10 10:58:12 CET [nas1b: scsitarget.fcp.dump.warning:warning]: FCP target SRAM dump disabled for adapter 0b, isp2400fct_process_ctio: [...]
Really you need an Oracle RAC database? I’m sure this question maybe a joke, but isn’t it. I’ve seens dozens of RAC database used simply to provide a clustering or a sort of failover and high availabilty service. But this is not true, definitly not. First if you ask for an Oracle database high availabilty [...]
I was looking online for this issue: are you able to know when a parameter was changed in your database or also track all parameters changes in your database? Kerry Osborne has the solution. Even if you’re able to check in your alert log file for changes (Oracle logs every changes to parameters) you can [...]
Do you know that there are more than thirty not documented and hidden parameters for tracing? You can find them with this query: select ksppinm "Parameter Name", ksppstvl "Value", ksppstdf "Default", from x$ksppi x, x$ksppcv y where x.indx = y.indx and ksppinm like ‘/_%trace%’ escape ‘/’ ; Note that Oracle 9i has about 26 parameters [...]
Sometimes you can get this error: [oracle@oratest03 scripts]$ emctl start dbconsole Environment variable ORACLE_UNQNAME not defined. Please set ORACLE_UNQNAME to database unique name. [oracle@oratest03 scripts]$ [oracle@oratest03 scripts]$ export ORACLE_UNQNAME=T11R2 [oracle@oratest03 scripts]$ emctl start dbconsole OC4J Configuration issue. /app/oracle/product/11.2.0.1/oc4j/j2ee/OC4J_DBConsole_oratest03_T11R2 not found. This is due to a misconfiguration of dbconsole during database setup. The fastest solution is [...]
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