Just a small Sunday night anecdote with a wider point. I, or maybe a colleague, recently received an update statement from a developer. Now, this developer is long of tooth and is well versed in the ways of Oracle data manipulation.
The aforementioned update statement contained an interesting hint. BYPASS_UJVC. You may not have heard of this hint. It’s not commonly used, although it’s been around since Oracle 8.1.5. Mainly because it is (more...)
If your company has a passing interest in database security, you are probably running some sort of session auditing at the very least [audit session] (although this can also be useful for troubleshooting connectivity issues). There’s a reasonable chance you’re also running some level of object auditing, or even DML access auditing if your employer so dictates:
Check access/change of objects in the DB
1 select audit_option, success, failure
2 from dba_stmt_audit_opts
I was pottering around with the sequence cache recently, investigating a few things like exactly when it refreshes (such as if it is flushed or aged from the shared pool – pin it!) and I was monitoring the next value using V$_SEQUENCE, like I have been since, erm, Oracle 8i in 1999 or summit.
I happened to log into an Oracle 220.127.116.11 DB for a check-test and it was empty! My (more...)
Sequences on Oracle databases are simple, but there are some basic truths about sequences which need to be understood if you are going to use them, especially on RAC:
- Sequences will have “holes” in them, even if you specify NOCACHE (e.g. if you rollback your transaction).
- Don’t specify NOCACHE. It doesn’t scale.
- Sequences will NOT necessarily be, erm, sequential for your transactions. That will depend upon the COMMIT order and if you are (more...)
One complication that you may face with replicating data using Goldengate (or other tools) is when your source character set is different to your destination character set. This is particularly true when the source character set is UTF-8 and the destination is not.
If the application does not sanitise (or you do not want to sanitise) inputs to restrict them to the lowest common denominator within your systems, you will need to ensure that you (more...)
Do you check the alert log of your databases every day? In the morning when you get in? But what about the alerts which happen during the day? How do you spot them – especially if you don’t have Grid Control or Cloud Control configured. Even if you do have a full monitoring solution, this can be useful for a belt-and-braces approach.
Here’s a short bash shell script to use adrci to read through each ORACLE_HOME (more...)
On Sunday I will be heading North from London to Liverpool for 4 days, to attend another UK Oracle User Group conference – #UKOUG_Tech14
I’m sure it will be as wonderful and informative a 4 days as you can get in the Oracle technical area. The hard part of attending is working out what and who to see.
I will be presenting there again – this time a talk on Goldengate late on the final (more...)
Wednesday’s word is Epicaricacy, meaning to take joy in the misfortune of others. Yes, this is the (admittedly rare) English word that doesn’t exist, causing an outbreak of German in otherwise sane sentence.
It’s interesting that taking pleasure from others misfortune as a single ‘concept'; Schadenfreude, skadeglädje, leedvermaak, skadefryd, skadeglädje and vahingonilo, are all Northern European words (being German, Swedish, Dutch, Danish, Norwegian and Finnish respectively). Us North Europeans seem to like little more that a good (more...)
I was at a talk recently, and there was an update by Jason Arneil about adding columns to tables with DEFAULT values in Oracle 12C. The NOT NULL restriction has been lifted and now Oracle cleverly intercepts the null value and replaces it with the DEFAULT meta-data without storing it in the table. To repeat the 11G experiment I ran recently:
SQL> alter table ncha.tab1 add (filler_default char(1000) default 'EXPAND' not (more...)