NOT IN and NULL

I posted about Unexpected results in June 2005. Here are more results from NOT IN and NULL select * from dual WHERE (1) NOT IN (SELECT NULL FROM DUAL); no rows selected select * from dual WHERE (1,1) NOT IN (SELECT NULL,1 FROM DUAL); no rows selected However, and this surprised me, select * from […]

MIN(DISTINCT X)

What is doing the MIN(DISTINCT X) call? Basically, every distinct value of X is passed to the MIN function. Well, it is probably of very little interest as the MIN function is very fast and processing less rows than MIN(X) should not boost the performance because of the overhead of sorting distinct values. However, if […]

next patchset for Oracle 10gR2

10.2.0.4 should be available this year on Linux x86. Check Metalink Certification for different plateforms. Certify – Additional Info Oracle Database – Enterprise Edition Version 10gR2 On Linux (x86) Operating System: Linux (x86) Version SLES-10 Oracle Database – Enterprise Edition Version 10gR2 N/A Version N/A Status: Certified Product Version Note: None available for this product. […]

ContentDB installation

Yesterday I installed ContentDB. The installation is fairly straightforward. Download and install Oracle Identity Management OID 10.1.4.0.1 Install the Infrastructure, with the Identity Management and Repository, including Internet Directory, Single Sign-on, Delegated Administration Services and Directory provisioning This will create a 10.1.0.5 database. The default parameters are too low for contentDB. alter system set processes=250 […]

Database Internals Newsletter October 2007

Oracle Support started a series about database internals. DATABASE INTERNALS NEWSLETTER Volume 1: October, 2007 Introduction to the Internals Newsletter Support Tips on Block Corruption What Constitutes a Severity 1 Issue? Note 460494.1

What is bigger than infinity?

Nan select BINARY_DOUBLE_INFINITY INF, BINARY_DOUBLE_NAN NAN, greatest(BINARY_DOUBLE_INFINITY, BINARY_DOUBLE_NAN) GRE from t; INF NAN GRE — — — Inf Nan Nan Nan means not a number. It could be square root of -1, log of -1, 0/0, acos(1000), Inf-Inf, etc… select SQRT(-1d), LN(-1d), 0/0d, acos(1000d), BINARY_DOUBLE_INFINITY-BINARY_DOUBLE_INFINITY from t; SQR LN- 00D ACO BIN — — — […]