Oracle

Full page logging in Postgres and Oracle

By Franck Pachot . In my opinion, the volume of logging (aka redo log, aka xlog, aka WAL) is the most important factor for OLTP performance, availability and scalability, for several reasons: This is the only structure where disk latency(…)

V$MYSTAT delta values

By Franck Pachot . Here is a little script I use from time to time to look at V$MYSTAT values and displaying on one line a set of statistics with their delta value between two calls.

Server process name in Postgres and Oracle

By Franck Pachot . Every database analysis should start with system load analysis. If the host is in CPU starvation, then looking at other statistics can be pointless. With ‘top’ on Linux, or equivalent such as process explorer on(…)

12cR2 PDB archive

By Franck Pachot . In 12.1 we had the possibility to unplug a PDB by closing it and generating a .xml file that describes the PDB metadata required to plug the datafiles into another CDB. In 12.2 we got an(…)

JAN18: Database 11gR2 PSU, 12cR1 ProactiveBP, 12cR2 RU

By Franck Pachot . If you want to apply the latest patches (and you should), you can go to the My Oracle Support Recommended Patch Advisor. But sometimes it is not up-todate. For example, for 12.1.0.2 only the PSU is(…)

Multitenant, PDB, ‘save state’, services and standby databases

By Franck Pachot . Creating - and using - your own services has always been the recommendation. You can connect to a database without a service name, though the instance SID, but this is not what you should do. Each(…)

Migrate Windows VM with more than 4 Disks from VMware to OVM

Suppose you got an OVA image created on VMware and the VM contains more than 4 Disks and you have to migrate this machine from VMware to OVM. As first step you import the OVA into the OVM in(…)

Result Cache: when *not* to use it

By Franck Pachot . I encountered recently a case where result cache was incorrectly used, leading to high contention when the application encountered a peak of load. It was not a surprise when I've seen that the function was called(…)

Testing Oracle SQL online

By Franck Pachot . Want to test some DDL, a query, check an execution plan? You need only a browser. And you can copy-paste, or simply link, your test-case in a forum, a tweet, an e-mail, a tweet. Here is(…)

Explain Plan format

By Franck Pachot . The DBMS_XPLAN format accepts a lot of options, which are not all documented. Here is a small recap of available information. The minimum that is displayed is the Plan Line Id, the Operation, and the Object(…)