DEFERRED CONSTRAINTS in PostgreSQL

Introduction

DEFERRED CONSTRAINTS are useful when you know that in a transaction you'll have inconsistent data for a while, like foreign keys that don't match, but you know that at the end of a transaction it will be consistent.

It was a nice PostgreSQL surprise to discover DEFERRED CONSTRAINTS, because it's not . . .

Posted in: postgresql

December 19, 2017

SQL Server trace flags

Introduction

Microsoft defines the trace flags as:

Trace flags are used to temporarily set specific server characteristics or to switch off a particular behavior.

The purpose of trace flags is to change a SQL Server default behavior. The context they apply to can be global, session or query and it depends . . .

Posted in: sqlserver

March 03, 2017

List all Ole DB Providers in Powershell

In Microsoft documentation for OleDbEnumerator.GetRootEnumerator() method
there's a C# example how to list all Ole DB Providers. I've just rewritten it in Powershell, creating a function that returns a list of providers, so it's easier to work with and can be filtered.
It's useful to check which providers are installed . . .

Posted in: oledbpowershell

June 21, 2016

PostgreSQL "Could not resolve client IP address to a host name" error

Using hostnames in pg_hba.conf

Since PostgreSQL 9.1 it's possible to use host names in pg_hba.conf.

I'm using it in a server and I got this error from a Java's client application trying to connect to it:

Caused by: org.postgresql.util.PSQLException: FATAL: no pg_hba.conf entry for host "192.168.1.2", user "my_user", . . .

Posted in: postgresql

June 03, 2016

Using functions on columns instead on literals

I always hear from developers that DBAs are against the use of ORMs (like Hibernate) without any reason. Before being a DBA, I was a developer and I recognize that I like to use ORMs because it makes it easier but you should always have in mind what’s beyond the ORM’s classes and what queries are executed by the ORM.

In other words: . . .

April 20, 2016

SQL Server vs PostgreSQL: fighting for resources in the same server

Introduction

Notice: This is not the typical performance’s comparative between SQL Server and PostgreSQL. I only test their performance’s affectation when they run in the same server, that I would never do.

We were asked: “Is it possible to run SQL Server and a PostgreSQL in the same server?”

Obviously, . . .

April 20, 2016

Learning in Internet’s era

In the last post of the year I’ll talk about knowledge and how we are continuously learning. The idea of the topic comes from a Packt Publishing offer: selling books for Xmas for \$5.

It doesn’t matter our job, it’s changing, so we’ve to evolve too. In fact, I don’t know any job that you don’t have to improve your skills continuously . . .