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.
In the last post we had a look at how EDB BART integrates into EDB PEM, so backups and restores can be managed centrally from the PEM console. Another tool that comes with an EDB subscription is EDB EFM (EDB Failover Manager). We again will not cover how that tool works or how you need to set it up, but…
When it comes to our PostgreSQL customers we basically have two types: There are customers that do not want to have a subscription. For these types of customers we go with plain community PostgreSQL and a choice of other open source components for supporting backup and recovery, high availability and monitoring/alerting. The other type of customer usually already has a…
From Oracle GoldenGate (OGG) version 12.2 and above, there is a transparent integration of OGG with Oracle Data Pump as explained in the Document ID 1276058.1. The CSN for each table is captured on an Oracle Data Pump export. The CSN is then applied to system tables and views on the target database on the import. These views and system…
If you are thinking about to move your MySQL databases to the Cloud but you are still reticent, you can maybe use the “Oracle Cloud Free Tier” offer to test it. Oracle Cloud Free Tier offers you 2 Oracle Autonomous Databases and 2 Oracle Cloud Infrastructure Compute VMs as Always Free services and in addition a 30-day Free Trial with…
In this blog post, I will show you what I did to troubleshoot an interesting problem with Memory on SQL Server. It all started with a job performing DBCC CHECKDB on all databases taking hours to complete instead of 10 minutes. So the Job ran outside of its maintenance window, still running in the morning when users come back to…
By Franck Pachot . Since Aug. 4, 2020 we have the possibility to rename an Autonomous Database (ATP, ADW or AJD – the latest JSON database) on shared Exadata infrastructure (what was called ‘serverless’ last year which is a PDB in a public CDB). As the PDB name is internal, we reference the ADB with its database name is actually…
Introduction A complaint I heard from customers about ODA is the low core speed of the Intel Xeon processor embedded in the X8-2 servers: Intel(R) Xeon(R) Gold 5218 CPU @ 2.30GHz. 2.30GHz only? Because of its comfortable number of cores (16 per processor), the cruise speed of each core is limited. Is it a problem compared to a home made…
By Franck Pachot . That’s common to any data structure, whether it is RDBMS or NoSQL, indexes are good to accelerate reads but slow the writes. This post explains the consequences of adding indexes in DynamoDB. Secondary Indexes What we call an index in DynamoDB is different from an index in RDBMS. They have the same goal: store your data…
In the following blog, you will learn how to install the latest version of the MariaDB Server 10.5.5 on CentOS 8 and how to use the mariadb user & binaries instead of mysql. As a reminder, MariaDB Server is highly scalable and can be either used as a Stand Alone, a Master/Slave or a Galera based MariaDB Cluster. MariaDB Server…
In a recent project we migrated an Oracle database previously running on 12.1.0.2 on an Oracle Database Appliance to an Exadata X8 with DB version 19.7. Shortly after the migration a merge-statement (upsert) failed with an ORA-07445: exception encountered: core dump [kdu_close()+107] [SIGSEGV] [ADDR:0xE0] [PC:0x1276AE6B] [Address not mapped to object] [] The stack looked as follows: kdu_close – updThreePhaseExe -…
By Franck Pachot . In The myth of NoSQL (vs. RDBMS) “joins dont scale” I explained that joins actually scale very well with an O(logN) on the input tables size, thanks to B*Tree index access, and can even be bounded by hash partitioning with local index, like in DynamoDB single-table design. Jonathan Lewis added a comment that, given the name…
By Franck Pachot . I have written a few blog posts about some NoSQL (vs. RDBMS) myths (“joins dont scale”, “agility: adding attributes” and “simpler API to bound resources”). And I’ll continue on other points that are claimed by some NoSQL vendors and are, in my opinion, misleading by lack of knowledge and facts about RDBMS databases. But here I’m…
