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.
The 2nd edition of 24HOP French Edition 2017 is over and we had great sessions about SQL Server and various topics ( SQL Server 2017 new features, Azure, PowerBI, High Availability , Linux, Hyper-convergence , Modeling …) If you did not attend to this event, you now have the opportunity to watch the videos of the different sessions. From my side,…
By William Sescu Per default, MariaDB is shipped with a utility called mysqldump for logical backups. For more information, please take a look at the following link. https://mariadb.com/kb/en/mariadb/mysqldump/ The mysqldump has advantages, e.g. it is easy to use and it is shipped with the standard MariaDB installation. So, no additional installation is needed. However, it has also some disadvantages. E.g.…
By Franck Pachot . I realize that I’m talking about indexes in Oracle and Postgres, and didn’t mention yet the best website you can find about indexes, with concepts and examples for all RDBMS: http://use-the-index-luke.com. You will probably learn a lot about SQL design. Now let’s continue on execution plans with indexes. As we have seen two posts ago, an…
There was a recent thread on the PostgreSQL general mailing list asking for GUI tools for PostgreSQL. This is question we get asked often at customers so I though it might be good idea to summarize some of them in a blog post. When you know other tools than the ones listed here which look promising, let me know so…
By Franck Pachot . Since X4 we can do Capacity on Demand on Exadata: disable some CPU cores to lower cost of Oracle Database licenses. Depending on the models, and the configuration, there are different minimums and here is a recap table about those. Here is the summary of Capacity on Demand minimum, maximum and increment. Those numbers come from the…
Imagine this scenario (which is not so uncommon): You have a lot of objects in a user schema and you want to grant another user access to that tables. You can easily do this by granting select on the tables to the user and you’re fine. Really? Maybe now, but what will happen when the user which owns the objects…
By Franck Pachot . In the previous post I said that an Index Only Access needs to find all rows in the index. Here is a case where, with similar data, Postgres can find all rows but Oracle needs additional considerations. In the previous post I’ve executed: select sum(n) from demo1 The execution plan was: Aggregate (cost=295.29..295.30 rows=1 width=8) (actual…
By Franck Pachot . In the previous post I’ve explained a sequential scan by accident: my query needed only one column which was indexed, and I expected to read the index rather than the table. And I had to hint the Oracle example to get the same because the Oracle optimizer chooses the index scan over the table scan in…
By Franck Pachot . With metered cloud services, keeping all your instances running may become expensive. The goal is to start them only when you need them. Here is a script that stops all instances you have on the Oracle Cloud Service PaaS. You can schedule it for example to stop them at the end of the business day, or…
By Franck Pachot . The latest version of SQL Developer, the 17.2 one released after Q2 of 2017, has a new item in the DBA view showing the Data Guard configuration. This is the occasion to show how you can cascade the log shipping in Oracle 12c A quick note about this new versioning: this is the release for 2017…
By Franck Pachot . Here is the first test I’ve done for my Postgres vs. Oracle access paths series and the first query did a sequential scan. It illustrates the first constant you find in the documentation for the query planner: seq_page_cost (floating point) Sets the planner’s estimate of the cost of a disk page fetch that is part of…
By Franck Pachot . I’ll start a series on Postgres vs. Oracle access paths because I know Oracle and I learn Postgres. While preparing it, I came upon some surprises because I’m so used to Oracle that I take some behavior as granted for any SQL databases. I recently posted a tweet about one of them, comparing latest Postgres version…
