(Michael Paquier) In PostgreSQL terminology, hint bints are a page-level mechanism implemented to be able to guess the visibility status of a tuple directly at the page level (actually whether the tuple xmin or xmax is committed or aborted), without going though checks in pg_clog and pg_subtrans whi

(Stephane Combaudon) A question often comes when talking about indexing: should we use multiple column indexes or multiple indexes on single columns? Peter Zaitsev wrote about it back in 2008 and the conclusion then was that a multiple column index is most often the best solution. But with all the r

(Giuseppe Maxia) In the last 10 years I have worked a lot with replication systems, and I have developed a keen interest in the topic of multiple masters in a single cluster. My interest has a two distinct origins:

(Miguel Angel Nieto) Table structures are stored in .frm files and in the InnoDB Data Dictionary. Sometimes, usually in data recovery issues, we need to recover those structures to be able to find the lost data or just to recreate the tables.

(Leo Hsu and Regina Obe) One of the features new to PostgreSQL 9.3 is the COPY FROM PROGRAM sql construct and in psql the equivalent copy from program. Michael Paquier covered the COPY TO/FROM PROGRAM in hist Postgres 9.3 feature highlight: COPY TO/FROM PROGRAM.

(Jon Jensen) Busy database-backed websites often hit scalability limits in the database first. In tuning MySQL, one of the first things to look at is the max_connections parameter, which is often too low. (Of course another thing to look at is appropriate fragment caching in your app server, HTTP ob

(Akshay Suryawanshi) One of the routine tasks for a DBA is renaming database schemas, and as such MySQL added a command to carry out that purpose called “RENAME DATABASE ”. However this command just made it through a few minor releases before being discontinued (from MySQL 5.1.7 to 5.

(Hans-Juergen Schoenig) Database security is always an essential issue in any database application. Especially when critical data is stored, it might be interesting to know who has changed which data when and how. To track those changes made to tables in PostgreSQL you can write yourself a generic c

(Dave Stokes) MySQL 5.6 introduced the ability to expire passwords. Many work environments have rules where it is mandatory to change passwords on a regular basis. It is easy to expire a single account with a ALTER USER ‘dave’@’localhost’ PASSWWORD EXPIRE; command.

(Morgan Tocker) Today I wanted to look at the relative merits of different optimization paths that can be taken on a Greenfield project. That is to say, one that has no constraints imposed on it by previous decisions made, and has received little to no optimization work to date.