Robert Jackson
Having studied a generic Business Computing degree at university, I was fortunate to do my work placement as an Oracle DBA. I enjoyed the challenges of the job and found that my skills were suited to it, also.
Since graduating with a 1st class honours degree in Computing - Database Systems, I have worked my way up from a Junior Oracle DBA to a DBA Team Leader.
Robert Jackson's Latest Posts
DBMS_STATS – Gathering Database Statistics
There are various thoughts on the correct way to gather statistics in a database. Do you collect them weekly/monthly/daily? Do you do it when the objects have had a certain level of changes made to them? Do you do it straight in PROD or test it in a QA environment first? In this article I […]
System Statistics in the Oracle Database
If you can, refer to Oracle’s Metalink note: 149560.1 Firstly, you must have DBA privileges or GATHER_SYSTEM_STATISTICS role to update dictionary system statistics. Secondly, Oracle recommends that you gather system statistics during peak load in order to give the optimizer the ability to choose the best plan based on system resource usage and throughput as well […]
ORA-28000 the account is locked
The Problem There are many reasons why you might get the ORA-28000 the account is locked error message, ranging from too many attempts at logging on with an incorrect password to a password which has expired and subsequently been automatically locked. In Oracle 10g the default password security mechanisms which were included in the default […]
11g Install File Not Found
The Problem I was installing the Oracle database 11g software. I had extracted the software from two zip files which were downloaded from Metalink. Two folders were created. When running the installation via the GUI, I received the error messages below, in addition to many other similar messages. File not found D:\Oracle\product\11.2\owb\external\oc4j_applications\applications\WFMLRSVCApp.ear D:\Oracle\product\11.2\oc4j\j2ee\oc4j_applications\applications\WFMLRSVCApp.ear D:\Oracle\product\11.2\owb\external\oc4j_applications\applications\WFMGRApp.ear D:\Oracle\product\11.2\owb\external\oc4j_applications\applications\WFMGRApp.ear […]
Control File Parallel Write Wait Event
Usually, you will find that high wait times on the control file parallel write wait event will be indicative of high log switching. The query below will show you which session performed control file transactions. select a.sid, decode(a.type, ‘BACKGROUND’, ‘BACKGROUND-‘||substr(a.program, instr(a.program,'(‘,1,1)), ‘FOREGROUND’) type, b.time_waited, round(b.time_waited/b.total_waits,4) average_wait, […]
AWR Report Shows High % and Wait Times
The Problem I was using an AWR report in order to carry out some testing on a DEV environment. After generating the AWR report, I noticed that the percentage differences and wait times on the report looked wrong. None of the percentages tallied up to 100% and the numbers were huge for a lot of […]
CPU Time in Top 5 Timed Events on Statspack/AWR Report
When I first take a look at a statspack or Automatic Workload Repository (AWR) report, and there have been no reported performance problems, I home in on the Top 5 Timed Events section toward the top of the AWR report. It is from here that you are able to get clues as to which direction you should go in, and therefore […]
Oracle Partitioning Fundamentals
Partitioning It’s a topic which a large amount of information could be written. There are so many ways to partition, good ways, bad ways, complicated ways and out right ugly ways! If you have read through the Oracle documentation you will know that there is a document written purely for very large databases and partitioning. […]
ORA-20000: index or partition of such index is in unusable state
The Problem During one of our overnight jobs which gathers statistics on several tables after having data loaded into them, the job failed with the ORA-20000 error message. The problem was because we had a partition splitting job which ran against the table which caused the indexes to become unusable after the partition had been […]
The Oracle STARTUP command
If you are only interested in learning how to restart Oracle please read the section lower down on “STARTUP FORCE”. This is a quick way to restart your Oracle database but it’s not the recommended or cleanest approach! Before I explain a little about how to start the Oracle database let’s clarify the different parts of […]
