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.
By Franck Pachot . This month, I’ll talk – with lot of demos – about multitenant internals at DOAG conference. The multitenant dictionary architecture starts with a simple idea: system metadata and data are in CDB$ROOT and user metadata and data are in PDB. And it could have been that simple. When a session connected to a PDB needs to…
By Franck Pachot . The documentation says that for Reduction of duplication and Ease of database upgrade the Oracle-supplied objects such as data dictionary table definitions and PL/SQL packages are represented only in the root. Unfortunately, this is only partly true. System PL/SQL packages are only in root but system table definition are replicated into all PDBs. This post is…
When you start using PostgreSQL 10 logical replication you might think it is a good idea to setup bi-directional replication so you end up with two or more masters that are all writable. I will not go into the details of multi master replication here (conflict resolution, …) but will show what happens when you try to do that. Lets…
By Franck Pachot . AWR collects segment statistics, and this can be used to quickly understand an abnormal database growth. Here is a script I use to get, from the AWR history, the segments that have grown by more than 1% of the database size, in one hour. First I must mention that this uses only the part of AWR…
Another interesting topic that popped up last week during pgconfeu: Are large objects supported with logical replication in PostgreSQL 10? The only truth is a test, isn’t it? Lets go… Obviously we need a table containing same large objects to start with: postgres=# create table t1 ( a int, b oid); CREATE TABLE Before inserting some data lets create a…
Today starts the Pass Summit 2017 taking place in Seattle. After a small fly over the Ocean, more than 10 hours… yesterday, and a nice jet lag which avoid me to sleep later than 4AM this morning, I arrived to the Convention Center in Seattle where the Pass takes place. I start this first day by the session of Itzik…
Today is the first day of the PASS SUMMIT 2017 in Seattle (WA). The weather is cloudy and we have only 11°C… but where is the problem? Everything happens inside! (at the Convention Center). In this blog, I will make a summary of main attack vectors against MSSQL environments, based on Argenis FERANDEZ’s session called “Modern Security Attack Vectors Against…
By Franck Pachot . Here is a quick SQL Developer report which display a chart about the Dbvisit replicate lag over the last hours The idea is to have the following chart showing the lag in MINE and APPLY processes. Here is an example where I stopped the replication to show some lag. The query is on the DBVREP.DBRSCOMMON_LAG_STATS on…
While doing the EDB quiz at their booth last week at pgconfeu one of the questions was: Are temporary tables auto vacuumed? What do you think? My first thought was yes, but lets see. The first question we need to answer is: How can we check if a table (no matter if temporary or not for now) was auto vacuumed…
By Franck Pachot . Here is a small warning. In Standard Edition, you may expect that the features that are not available for your edition are blocked, but in 12.2 you can create more than one PDB in Standard Edition, and you should set MAX_PDBS to prevent that. 12cR1 In 12.1 Standard Edition, when you try to create more than…
By Mouhamadou Diaw As you may know the parameter STANDBY_FILE_MANAGEMENT enables or disables automatic standby file management. When automatic standby file management is enabled, operating system file additions and deletions on the primary database are replicated on the standby database. It is generally recommended to set this parameter to AUTO, but it can happen that this parameter is set to…
By Franck Pachot . The development teams often see the database as a ‘persistence layer’ only. And sometimes it is mentioned that the database is always the cause of the problems, especially when implementing continuous integration and trying to be agile. Then cames the idea to have this ‘persistence layer’ in an isolated environment, such as a docker container, with…
