Author: Laurent Schneider

sys_connect_by_path in 8i or the danger to use undocumented parameters…

I have been posting on metalink technical forum about a query that I run against all my test databases but did not work in production. as it simpliest form select sys_connect_by_path(dummy,’:’) from dual connect by 1=2; well, there is nothing wrong with this query. I tried it on 8i, 9iR2, 10gR1 10gR2 and it worked […]

oracle10gR2 on suse10

I prefer and recommend using Oracle on a supported version, like Suse Entreprise 9, because the installation is fair. The Installer does complain on SLES9 what is missing. Ok, I just received a brand new notebook, I decided to go to Suse 10, and, Ô Miracle, the installation was pretty easy! I surely installed C++ […]

Tom Day 3 : read consistency, transparent data encryption, dbms_advanced_rewrite

Day 3 concludes the Tom workshop in Switzerland. We started with read consistency and write consistency, with an interesting example were a single row update could make a big job run thrice slower, because of the write consistency. Once again, Tom insist on saying that you must understand Oracle to write applications. Tom demonstrates a […]

Tom Kyte Day 1

Day one was quite interesting! We learnt a lot of staff about tuning approach, I have got confirmation that most of the “WE KNOW THAT, IT HAS ALWAYS BEEN SO” were maybe one day true, but are no longer, for example “separate index and tables”, or, delightfull, “you must periodically reorganise your tables”. I also […]

encrypted listener password

There a few major changes in the database administration and the database security between 9i and 10g. In 9i, I used to grep in the listener.ora to find out the password. LISTENER_LSC61 = (DESCRIPTION=(ADDRESS_LIST= (ADDRESS=(PROTOCOL=TCP)( )) PASSWORDS_LISTENER_LSC61 = 1234567890ABCDEF this 64bit encrypted string can be used in 9i to stop the listener $ lsnrctl LSNRCTL […]

add_years and years_between

I just wrote those two functions add_years and years_between they work similary to add_months and months_between, with the exception of leap years. there is exactly 1 year between 28-feb-2003 and 28-feb-2004 there is 1.00273224 year (1+1/366) between 28-feb-2003 and 29-feb-2004 there is 0.99726776 year (1-1/366) between 29-feb-2004 and 28-feb-2005 there is exactly 1 year between […]

Welcome to Switzerland

I will attend Tom Kyte 3-days session in Zurich in 2 weeks. I am immensely impatient to follow his workshop ! I hope palindnilap will be there too 😉 I invited him to come to my home to go to Tom Workshop, and to have a game of xiangqi on the brand new wooden board […]

post from palindnilap

I just answered a question about the data dictionary on It is all about the dictionary views. How many tables should I know in the dictionary ? SQL> select count(*) from dict; 1857 Well, that’s too much. But I can remove the GV$ view, which contain the instance for RAC, and the DBA_ ALL_ […]

oracle voyage worm

I wrote a mini script to protect my customer from being attacked by an “oracle voyage worm” variant : revoke CREATE DATABASE LINK from CONNECT; revoke ALL on SYS.UTL_FILE from PUBLIC; revoke ALL on SYS.UTL_HTTP from PUBLIC; revoke ALL on SYS.UTL_SMTP from PUBLIC; revoke ALL on SYS.UTL_TCP from PUBLIC; grant EXECUTE on SYS.UTL_FILE to XDB; […] hidden parameters

In order to get a clean database configuration, I add the following two hidden parameters in my parameter file. Do not hurl that loud, I hear you from here! Well, as I said already about the _pga_max_size, I never recommend using hidden parameters when you can do the same without. However, I am going […]

ldap day 2

what can I do with LDAP? what is the difference between LDAP and Oracle Internet Directory? Well, there is quite a lot of interresting documents, pictures and faq on otn : OTN Directory homepage Directory Admin guide Identity Management ReferenceLDAP is a directory server, the info are stored in an Oracle database. When you […]

ldap server

My ldap server is up and running on my notebook with SLES9. Next, next, next, install. That is it. Oracle Application Server creates a database and start the Oracle Internet Directory – understand LDAP server – automatically. It can then be configured with the web interface.

Details regarding the 10g DBA OCM requirements will be available in December

Well, when 10g certification came out, it said : “will be available in late 2004”. In March 2005, I contacted Oracle University in Germany. They said : keep watching Later, it said : “will be available in mid 2005”. In Open World, I met the certification principal, who meant it will start in December […]


what is a hierarchy? I enjoy reading the wikipedia definition : In the doc the hierarchy is as a parent-child connection, CONNECT BY PRIOR defines the relationship. However, it is possible to have under certain circumstances to connect to a child, regardsless of the parent. This is no longer a practical relation. Sterile variant […]