SQL Server

Franck Pachot's picture

Data virtualization on SQL Server with Redgate SQL Clone

By Franck Pachot

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In the previous blog post I’ve installed SQL Server on the Oracle Cloud. My goal was actually to have a look at Redgate SQL Clone, a product that automates thin cloning. The SQL Server from the Oracle marketplace is ok for SQL Clone prerequisites. There’s a little difference in .NET Framework version (I have 4.6 where 4.7.2 or later is required but that’s fine – if it was not an update would be easy anyway).

Franck Pachot's picture

SQL Server on Oracle Cloud

By Franck Pachot

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You can create a VM with SQL Server running in the Oracle Cloud. This is easy with a few clicks on the marketplace:

Franck Pachot's picture

DBPod – le podcast Bases de Données

By Franck Pachot

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J’essaie quelque chose de nouveau. Je publie beaucoup en anglais (blog, articles, présentations) mais cette fois quelque chose de 100% francophone. En sortant du confinement, on reprend les transports (train, voiture,…) et c’est l’occasion de se détendre en musique mais aussi de s’informer avec des podcasts. J’ai l’impression que c’est un format qui a de l’avenir: moins contraignant que regarder une video ou ou lire un article ou une newsletter. Alors je teste une plateforme 100% gratuite: Anchor (c’est un peu le ‘Medium’ du Podcast).

Franck Pachot's picture

The myth of NoSQL (vs. RDBMS) agility: adding attributes

By Franck Pachot

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There are good reasons for NoSQL and semi-structured databases. And there are also many mistakes and myths. If people move from RDBMS to NoSQL because of wrong reasons, they will have a bad experience and this finally deserves NoSQL reputation. Those myths were settled by some database newbies who didn’t learn SQL and relational databases. And, rather than learning the basics of data modeling, and capabilities of SQL for data sets processing, they thought they had invented the next generation of persistence… when they actually came back to what was there before the invention of RDBMS: a hierarchical semi-structured data model. And now encountering the same problem that the relational database solved 40 years ago. This blog post is about one of those myths.

Franck Pachot's picture

How SQL Server MVCC compares to Oracle and PostgreSQL

By Franck Pachot

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Microsoft SQL Server has implemented MVCC in 2005, which has been proven to be the best approach for transaction isolation (the I in ACID) in OLTP. But are you sure that writers do not block readers with READ_COMMITTED_SNAPSHOT? I’ll show here that some reads are still blocked by locked rows, contrary to the precursors of MVCC like PostgreSQL and Oracle.

For this demo, I run SQL Server 2019 RHEL image on docker in an Oracle Cloud compute running OEL7.7 as explained in the previous post. If you don’t have the memory limit mentioned, you can simply run:

docker run -d -e "ACCEPT_EULA=Y" -e 'MSSQL_PID=Express' -p 1433:1433 -e 'SA_PASSWORD=**P455w0rd**' --name mssql mcr.microsoft.com/mssql/rhel/server:2019-latest

Franck Pachot's picture

How SQL Server MVCC compares to Oracle and PostgreSQL

By Franck Pachot

.
Microsoft SQL Server has implemented MVCC in 2005, which has been proven to be the best approach for transaction isolation (the I in ACID) in OLTP. But are you sure that writers do not block readers with READ_COMMITTED_SNAPSHOT? I’ll show here that some reads are still blocked by locked rows, contrary to the precursors of MVCC like PostgreSQL and Oracle.

For this demo, I run SQL Server 2019 RHEL image on docker in an Oracle Cloud compute running OEL7.7 as explained in the previous post. If you don’t have the memory limit mentioned, you can simply run:

docker run -d -e "ACCEPT_EULA=Y" -e 'MSSQL_PID=Express' -p 1433:1433 -e 'SA_PASSWORD=**P455w0rd**' --name mssql mcr.microsoft.com/mssql/rhel/server:2019-latest

Franck Pachot's picture

Running SQL Server on the Oracle Free tier

By Franck Pachot

The Oracle Cloud is not only for Oracle Database. You can create a VM running Oracle Linux with full root access to it, even in the free tier: a free VM that will be always up, never expires, with full ssh connectivity to a sudoer user, where you are able to tunnel any port. Of course, there are some limits that I’ve detailed in a previous post. But that is sufficient to run a database, given that you configure a low memory usage. For Oracle Database XE, Kamil Stawiarski mentions that you can just hack the memory test in the RPM shell script.

Franck Pachot's picture

Running SQL Server on the Oracle Free tier

By Franck Pachot

The Oracle Cloud is not only for Oracle Database. You can create a VM running Oracle Linux with full root access to it, even in the free tier: a free VM that will be always up, never expires, with full ssh connectivity to a sudoer user, where you are able to tunnel any port. Of course, there are some limits that I’ve detailed in a previous post. But that is sufficient to run a database, given that you configure a low memory usage. For Oracle Database XE, Kamil Stawiarski mentions that you can just hack the memory test in the RPM shell script.

dbakevlar's picture

How Not to Perform a Difficult Update in SQL Server/Azure

I learned a long time ago, that the quickest way to do something was to not do it at all.

A friend of mine asked me if I could review an update statement that was confounding their group looking for ways to optimize it.

The table has, just short of 50 columns, a considerable number of indexes and the column in question, has a datatype set to NVarChar(8), consists of some numbers, combinations of letters and numbers, etc.

The process would take 7 ½ hours to run this update, as it parses through 100K rows at a time. There is one index that includes the CN1 column in it, but no index on just the CN1 column. This is what the update statement looks like:

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