Tag: dba

18c XE is live!

Just a quick post because this is perhaps what I think is one of the biggest game changers for the Oracle Database. 18c Express Edition (18x XE) is now available for general use. For those people with experience with 11g XE, this might not…

Compressed LOB–my table got bigger?

We had an interesting question on AskTOM the other day about LOB compression. Someone was very concerned that after applying compression to the LOBS in the column of their table, the table actually got larger! Cue much confusion and panic, but after a little…

LOBs vs Data – when compression occurs

Just a quick tip for SECUREFILE lobs. You may be familiar with basic compression on data in tables. It is a dictionary attribute of the table, which is then taken into account when you perform: a SQL Loader direct load, or an INSERT with…

Partial Indexes–Take Care With Truncate

Partial indexes are a very cool feature that came along with Oracle 12c. The capability at partition level to control index existence allows for a couple of obvious use cases: 1) You index the data in recent partitions only, because small amounts of data…

Correcting datatypes with minimal downtime

Just a quick post here by request of an attendee of the September Office Hours. I had a demo converting the data type of a primary key without losing data and with minimal impact to the availability of the database using DBMS_REDEFINITION.  You can…

Another little 12c improvement

You’ve got a huge table right? Massive! Immense! And then something bad happens. You get asked to remove one of the columns from that table. “No problem” you think. “I won’t run the ‘drop column’ command because that will visit every block and take…

Partial indexing – get the dictionary definitions right

Just a quick post to clear up some confusion that can be seen on the partial indexing capabilities in Oracle Database 12c and above. I was at an event in the Oracle Perth office last week, and an attendee mentioned that they thought the…