Everything our consultants learn while running databases for customers: Oracle, PostgreSQL, SQL Server, MySQL, MariaDB, MongoDB and Delphix. Expect hands-on posts about installation, day-to-day administration, backup and recovery, performance tuning, replication and upgrades.
You might wonder, but yes, Veritas is still alive and there are customers that use it and are very happy with it. Recently we upgraded a large cluster from Veritas 5/RHEL5 to Veritas InfoScale 7.3/RHEL7 and I must say that the migration was straight forward and very smooth (when I have time I’ll write another post specific to the migration).…
A recent tweet from Kevin Closson outlined that in PostgreSQL it might be confusing if something is an index or table. Why is it like that? Lets have a look and start be re-building the example from Kevin: For getting into the same situation Kevin described we need something like this: postgres=# create table base4(custid int, custname varchar(50)); CREATE TABLE…
By Franck Pachot . The title of this blog post was: “Tracing DBMS_RCVMAN for reclaimable archivelogs” until I started to write the conclusion… In a previous post I mentioned that there’s a bug with archivelog deletion policy when you want to mention both the ‘BACKED UP … TIMES TO …’ and ‘APPLIED’ or ‘SHIPPED’ as conditions for archived logs to…
By Franck Pachot . There are several bugs with the optimizer in FIRST_ROWS mode. Here is one I encountered during a 10.2.0.4 to 12.2.0.1 migration when a view had an ‘order by’ in its definition. Here is the test case that reproduces the problem. A big table: SQL> create table DEMO1 (n constraint DEMO1_N primary key,x,y) as select 1/rownum,’x’,’y’ from…
A recent tweet of mine resulted in Martin Widlake to write a really great blog post about What makes a community. Please read it before you continue to read this. There was another response from Stefan Koehler which is worth mentioning as well. Both, Martin and Stefan, speak about Oracle communities because this is were they are involved in. At…
It has been quite a while since the last post in this series but today comes the next one. Being at a customer this morning this question popped up: Can we have instead of triggers on a view in PostgreSQL as well? I couln’d immediately answer (although I was quite sure you can) so here is the test. I took…
Some days ago EDB Postgres Advanced Server 10 was released and one feature which might be handy is auto pre-warming. What this does is to save all the buffers (or better a description of the buffers) which are currently loaded in to shared_buffers to disk and then re-read the buffers automatically when the instance is restarted. Lets see how it…
By Franck Pachot . On datawarehouse databases, I frequently recommend increasing the level of dynamic sampling because: Queries have complex predicates with AND, OR, IN(), ranges and correlated values for which the optimizer cannot estimate the cardinality properly Queries are long anyway (compared to OLTP) and can afford more parse time to get an optimized execution plan However, there’s a…
Did you ever wonder what exactly is in a PostgreSQL data file? Usually you don’t care, I agree. But there might be situations where knowing how you can do this might be a great help. Maybe your file is corrupted and you want to recover as much data as possible? Maybe you just want to do some research. There is…
After having worked with OVM on various architectures I can say that it is a good technology to easily build virtualized environments for production applications. Because it is based on XEN and has simple ways to deal with existing storage (FC, ISCSI, NFS, …) and networking solution (bond, lacp, …) it is a robust and convenient way to virtualized IT…
Before SQL Server 2016, you had the possibility to check the case “Send Windows and SQL Server Error Reports….” during the installation if you want to be a part of the Customer Experience Improvement Program (CEIP). In SQL Server 2016, after the installation, all of the CEIP are automatically turned on. Why? SQL Server and SQL Azure share the same…
Last Friday I saw a very interesting session in Pass Summit 2017 about how to Bypass, or Ensure, SQL Server security by Matt Martin. Matt explained us how to bypass SQL Server security with the complicity of your SQL Server DBA. Msdb is the most powerful database to get stuff done: mail, jobs… so let’s have a look how to…
