(Bertram Moshier) People traditionally think of differences between two dates in the form of years, months, and days instead of simply days or months with fractional portions. While Oracle provides easy to use methods to compute the differences between two dates (e.g. subtraction of dates or the ont

(Jonathan Gennick) You’re writing a query that returns computed column values. As input to your calculations, you need values from multiple rows. What do you do? This is actually a fairly common problem. Solutions to it often involve inscrutable combinations of self-joins and subqueries. Oracle

(Steven Feuerstein) What is refactoring? Most PL/SQL developers stay very busy building applications. As a result, relatively few explore the wider world of software programming, in which the topic of refactoring is known.

(Galina Petrenko) This script displays instance background process information. The script works when the database is MOUNTed or OPENed. (script)

(Amar Kumar Padhi) In Oracle, a query may be executed in more than one way. The execution plan that has the best ranking or the lowest cost is the one that will return output with the fastest rate and optimal utilization of resources. The execution plan is generated by the Optimizer. Optimizer is an

(James Koopmann) The days of building your own DDL extraction utilities are almost gone. While Oracle has given us a simplistic approach to look at the DDL, it isn’t quite everything we would hope for.

(Jonath1n Gennick) I don’t usually write about new Oracle features for this list, because so few people can use them, but this time I’m going to break that pattern. Oracle Database 10g brings a new feature called the “partition outer-join”. You use the feature to “densify” data, to fill in missing

When an SQL request is commonly issued using multiple columns, a concatenated or multi-column index can be used to improve performance. Oracle supports the use of multi-valued indexes, but there are some important limitations. Unlike other relational databases, Oracle requires that all columns in th

(Sanjay Ray) This script generates a spool file that can be run from a SQL*Plus session to list the differences between 2 tables with identical structure. This can be useful if 2 similar tables need to be compared across different schemas (or different databases, in which case a local view will

These notes introduce the Oracle server architecture. The architecture includes physical components, memory components, processes, and logical structures.