All Things Oracle Full Articles

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All databases stand on a tripod of datatypes: strings, numbers and dates. And so I’d imagine that by Day 2 or so of dabbling with Oracle you’d be starting to get reasonably comfortable with the VARCHAR2, NUMBER and TIMESTAMP data types. And that’s a good thing, familiarity with those three data types will take you a long way into a… Continue Reading →

All Things Oracle Full Articles

PartitionedIndexEfficiency Although it is generally true that rebuilding an index represents a waste of time and resources, there nevertheless exist situations where degenerated indexes might benefit from reorganisation. When you think you are in such a situation, instead of shooting in the dark and rebuilding all indexes, you are better off finding and rebuilding only those indexes occupying more space… Continue Reading →

All Things Oracle Full Articles

Oracle RAC One Node, introduced in Oracle Database 11g Release 2 (11.2.0.2), is a single instance of an Oracle RAC-enabled database running on one node in a cluster. It lets you consolidate multiple databases onto a single cluster while providing high availability benefits of failover protection to the single instance databases. Oracle RAC One Node databases can be configured to… Continue Reading →

All Things Oracle Full Articles

In the 3rd part of this series, I introduced you to the concept of the bind variables. We also learned their importance in regard to cursors, i.e. how with the presence of bind variables, cursor reparsing can be reduced significantly. But as is famously said in the world of performance tuning, there is nothing black or white: it’s all grey…. Continue Reading →

All Things Oracle Full Articles

All databases stand on a tripod of datatypes: strings, numbers and dates. And though they might dress them in fancy clothing – varchar2, clob, float, integer – strings are really just strings, and numbers are really just numbers. But dates — dates are interesting. In this article I’ll talk to you about dates, about time, and about how both are… Continue Reading →

All Things Oracle Full Articles

Here’s a simple trick you can play on your friends. Ask them to pick a number from 1 to 10, and tell them you’ll read their mind and magically extract from it the number they’ve chosen. Don’t give them too long to choose; then put on your best imitation of a magician and say… 7. I don’t know why, but… Continue Reading →

All Things Oracle Full Articles, Application Development, Database Development

At times, we might need to duplicate a production pluggable database to a Past Point in Time without disturbing the production database itself, in order to: View the data in the Production Database (PDB) as it appeared then Perform testing Generate reports, etc. Duplication of a PDB slightly differs from that of a non-CDB. In order to duplicate the PDB, an… Continue Reading →

All Things Oracle Full Articles

Snapshots

Jonathan Lewis on 24 January 2017 with 0 comments

While looking at the results from a query against the dynamic performance view v$active_session_history during a recent trouble-shooting assignment I noticed a result that was so unusual that I decided I needed to get some information from the v$ash_info view over an interval of about 3 minutes – and it didn’t matter which three minutes in particular, any three (consecutive)… Continue Reading →

12c, All Things Oracle Full Articles, Oracle Database, Troubleshooting

In the previous post I described a problem with the strategy that the optimizer uses for costing an index fast full scan, and the alternative strategy that Oracle had supplied at some point in the 10g timeline to allow a more rational cost to be calculated in special cases. In an earlier post still I had described the problem with… Continue Reading →

All Things Oracle Full Articles, Oracle Database, Troubleshooting

In the first and the second parts of this series, we learned what query parsing is, how hard and soft parsing work, what their impact on the query is, and then moved on to understand the concept of parent and child cursors. In this third article, we will look at the issue of duplicate SQL statements and how Bind Variables… Continue Reading →

All Things Oracle Full Articles, Performance Tuning