Hacking Indexes

Jonathan Lewis on 03 October 2016 with 3 comments

Indexes are expensive to maintain so we want to get the greatest benefit we can from them and make sure that Oracle uses them whenever it’s appropriate. Sometimes, though, the optimizer seems to ignore indexes that we think would be very effective and when this happens it’s often because the statistics that Oracle has gathered do not reflect the quality… Continue Reading →

All Things Oracle Full Articles, Performance Tuning, Troubleshooting

There’s a possibility you’ve parachuted into this series on JSON and Oracle at this point. If you are already familiar with what JSON is and how it is created, and are only interested in discovering how to wrestle JSON data from an Oracle database, then you’re welcome, grab a seat. However, if you see the words JSON and Oracle, and… Continue Reading →

All Things Oracle Full Articles, Database Development

Introduction Oracle Database 10g Release 1 introduced Automatic Storage Management (ASM), a new framework for managing Oracle database files. ASM provides a foundation for highly efficient storage management with direct I/O, redundancy, striping and load balancing. Files stored on ASM are evenly distributed across disks in a disk group and mirrored according to the policies defined in the disk group…. Continue Reading →

10g, 11g, 12c, All Things Oracle Full Articles

Rebuilding indexes is an activity that you shouldn’t need to do often. There are always a few special cases – like when you’ve moved or recreated a table or if you’ve done a massive delete on a table – when it’s probably a reasonable idea but, in general, there are very few cases where there’s any great benefit to be… Continue Reading →

All Things Oracle Full Articles, Oracle Database, Troubleshooting

The Oracle Database In-Memory option was introduced in Oracle 12c ( patch set). By using the In-Memory option, businesses can benefit from better decisions made in real time, improved productivity, increased competitiveness and lowered costs. The Oracle In-Memory option is designed to fit both Data warehouse and mixed workload OLTP databases, and can be deployed with any existing application that… Continue Reading →

12c, All Things Oracle Full Articles

Cloning of a Pluggable Database (PDB) in Oracle Multitenant is a great feature and is very useful. Oracle Database 12c Release 1 has introduced various enhancements to the cloning of Pluggable Databases to overcome the limitations imposed by the initial release of Oracle Database 12c ( In Oracle PDBs can be hot cloned, i.e. you don’t need to put the source PDB… Continue Reading →

12c, All Things Oracle Full Articles

Welcome to part three in this series of articles about Oracle and its uneasy romance with JSON. Uneasy? Well, that’s a bit of a spoiler; so far it’s been smooth sailing. Part 1 was a precis of JSON, while Part 2 delved into the reasons for Oracle’s involvement in the area. So far so good; but now we’ve got to… Continue Reading →

All Things Oracle Full Articles

In the initial release of Oracle 12c (, a non-Container Database (non-CDB) could be converted to a pluggable database (PDB) using any of the following methods: Using DBMS_PDB Using datapump (expdb, impdp) Using GoldenGate replication The patchset has introduced the ability to clone a remote non-CDB as a PDB directly over the network. Remote Cloning of a Non-CDB is a… Continue Reading →

12c, All Things Oracle Full Articles

Text Indexes

Jonathan Lewis on 05 September 2016 with 4 comments

The Oracle database has many features that are not spoken of frequently and a recent note by Connor McDonald reminded me that there are a couple of notes about optimising Text indexes that have been on my “must write” list for several years. If you’re not familiar with what text indexes can do for you, here’s a thumbnail sketch: create… Continue Reading →

All Things Oracle Full Articles

Introduction When it comes to tuning a badly-performing query, there are many things that need to be checked. There may be poor query design causing the query to run slowly. There could be an issue with the underlying hardware such as CPU or IO which is bringing the performance of the query down. There could be stale statistics or missing… Continue Reading →

All Things Oracle Full Articles