Blog - Page 2 of 6 - Vettabase

How to delete duplicate rows in MariaDB

Posted on 28 November 2021 by Federico Razzoli — No Comments ↓

<img width="283" height="200" src="https://vettabase.com/blog/wp-content/uploads/2021/05/training_mariadb_small.jpeg" class="attachment-featured-slider size-featured-slider wp-post-image" alt="" srcset="https://vettabase.com/blog/wp-content/uploads/2021/05/training_mariadb_small.jpeg 283w, https://vettabase.com/blog/wp-content/uploads/2021/05/training_mariadb_small-16x12.jpeg 16w" sizes="(max-width: 283px) 100vw, 283px" />

How to remote duplicate values from a table to add a UNIQUE index, in MariaDB. Continue reading How to delete duplicate rows in MariaDB→

The importance of maintenance windows

Posted on 25 October 2021 by Federico Razzoli — No Comments ↓

<img width="640" height="318" src="https://vettabase.com/blog/wp-content/uploads/2021/10/maintenance_windows-640x318.png" class="attachment-featured-slider size-featured-slider wp-post-image" alt="" loading="lazy" srcset="https://vettabase.com/blog/wp-content/uploads/2021/10/maintenance_windows-640x318.png 640w, https://vettabase.com/blog/wp-content/uploads/2021/10/maintenance_windows-16x7.png 16w" sizes="(max-width: 640px) 100vw, 640px" />

Periodical maintenance windows can be healthy both for your team and your infrastructure. Business won’t be damaged. Continue reading The importance of maintenance windows→

The costs of using multiple database technologies

Posted on 3 October 2021 by Federico Razzoli — No Comments ↓

<img width="640" height="318" src="https://vettabase.com/blog/wp-content/uploads/2021/10/introducing_new_databases-1-640x318.png" class="attachment-featured-slider size-featured-slider wp-post-image" alt="" loading="lazy" srcset="https://vettabase.com/blog/wp-content/uploads/2021/10/introducing_new_databases-1-640x318.png 640w, https://vettabase.com/blog/wp-content/uploads/2021/10/introducing_new_databases-1-16x8.png 16w" sizes="(max-width: 640px) 100vw, 640px" />

Before introducing a new database technology in your organisation, consider the drawbacks. Continue reading The costs of using multiple database technologies→

How slow is SELECT * ?

Posted on 18 September 2021 by Federico Razzoli — 4 Comments ↓

<img width="600" height="311" src="https://vettabase.com/blog/wp-content/uploads/2021/09/select_star.png" class="attachment-featured-slider size-featured-slider wp-post-image" alt="" loading="lazy" srcset="https://vettabase.com/blog/wp-content/uploads/2021/09/select_star.png 600w, https://vettabase.com/blog/wp-content/uploads/2021/09/select_star-300x156.png 300w, https://vettabase.com/blog/wp-content/uploads/2021/09/select_star-16x8.png 16w" sizes="(max-width: 600px) 100vw, 600px" />

The most widely known query optimisation rule is that developers should always avoid SELECT *. Even when all columns are needed, they should list their names, because more columns could be created in the future. But developers find this really Continue reading How slow is SELECT * ?→

Identify useless queries in MariaDB/MySQL

Posted on 7 September 2021 by Federico Razzoli — No Comments ↓

<img width="600" height="237" src="https://vettabase.com/blog/wp-content/uploads/2021/09/identify_useless_queries.png" class="attachment-featured-slider size-featured-slider wp-post-image" alt="" loading="lazy" srcset="https://vettabase.com/blog/wp-content/uploads/2021/09/identify_useless_queries.png 600w, https://vettabase.com/blog/wp-content/uploads/2021/09/identify_useless_queries-300x119.png 300w, https://vettabase.com/blog/wp-content/uploads/2021/09/identify_useless_queries-16x6.png 16w" sizes="(max-width: 600px) 100vw, 600px" />

Some queries always fail or never return rows. They should be eliminated to improve database performance. Continue reading Identify useless queries in MariaDB/MySQL→

NULL comparisons in MariaDB, PostgreSQL, and SQLite

Posted on 6 September 2021 by Federico Razzoli — No Comments ↓

<img width="600" height="311" src="https://vettabase.com/blog/wp-content/uploads/2021/09/null_comparisons-1.png" class="attachment-featured-slider size-featured-slider wp-post-image" alt="" loading="lazy" srcset="https://vettabase.com/blog/wp-content/uploads/2021/09/null_comparisons-1.png 600w, https://vettabase.com/blog/wp-content/uploads/2021/09/null_comparisons-1-300x156.png 300w, https://vettabase.com/blog/wp-content/uploads/2021/09/null_comparisons-1-16x8.png 16w" sizes="(max-width: 600px) 100vw, 600px" />

Comparisons are tricky when NULL values are involved. But some databases offer some special, handy syntax to solve the problem. Continue reading NULL comparisons in MariaDB, PostgreSQL, and SQLite→

Choosing Cassandra consistency levels

Posted on 9 August 2021 by Federico Razzoli — 2 Comments ↓

<img width="600" height="311" src="https://vettabase.com/blog/wp-content/uploads/2021/08/cassandra_choose_consistency_level.jpeg" class="attachment-featured-slider size-featured-slider wp-post-image" alt="" loading="lazy" srcset="https://vettabase.com/blog/wp-content/uploads/2021/08/cassandra_choose_consistency_level.jpeg 600w, https://vettabase.com/blog/wp-content/uploads/2021/08/cassandra_choose_consistency_level-300x156.jpeg 300w, https://vettabase.com/blog/wp-content/uploads/2021/08/cassandra_choose_consistency_level-16x8.jpeg 16w" sizes="(max-width: 600px) 100vw, 600px" />

Choose the best balance between speed and consistency by setting proper consistency levels. Continue reading Choosing Cassandra consistency levels→

ALERT: Many Cassandra users may need an urgent upgrade

Posted on 28 July 2021 by Federico Razzoli — No Comments ↓

<img width="446" height="300" src="https://vettabase.com/blog/wp-content/uploads/2021/06/hours_smaller.jpeg" class="attachment-featured-slider size-featured-slider wp-post-image" alt="Vettabase Monthly Time" loading="lazy" srcset="https://vettabase.com/blog/wp-content/uploads/2021/06/hours_smaller.jpeg 446w, https://vettabase.com/blog/wp-content/uploads/2021/06/hours_smaller-300x202.jpeg 300w, https://vettabase.com/blog/wp-content/uploads/2021/06/hours_smaller-16x12.jpeg 16w" sizes="(max-width: 446px) 100vw, 446px" />

Vettabase Monthly Time

Cassandra 4.0 GA was released on 26th July 2021. Older versions users need to upgrade quickly. Continue reading ALERT: Many Cassandra users may need an urgent upgrade→

Automating interactive programs execution with Expect

Posted on 13 July 2021 by Federico Razzoli — No Comments ↓

<img width="640" height="318" src="https://vettabase.com/blog/wp-content/uploads/2021/07/automate_interactive_programs_with_expect-640x318.jpeg" class="attachment-featured-slider size-featured-slider wp-post-image" alt="" loading="lazy" srcset="https://vettabase.com/blog/wp-content/uploads/2021/07/automate_interactive_programs_with_expect-640x318.jpeg 640w, https://vettabase.com/blog/wp-content/uploads/2021/07/automate_interactive_programs_with_expect-16x8.jpeg 16w" sizes="(max-width: 640px) 100vw, 640px" />

How we automated the creation of immudb users and databases with the help of the Expect language. Continue reading Automating interactive programs execution with Expect→

Cassandra login error: Cannot achieve consistency level LOCAL_ONE

Posted on 9 July 2021 by Federico Razzoli — No Comments ↓

<img width="640" height="318" src="https://vettabase.com/blog/wp-content/uploads/2021/07/cassandra_cannot_achieve_local_one-640x318.jpeg" class="attachment-featured-slider size-featured-slider wp-post-image" alt="" loading="lazy" srcset="https://vettabase.com/blog/wp-content/uploads/2021/07/cassandra_cannot_achieve_local_one-640x318.jpeg 640w, https://vettabase.com/blog/wp-content/uploads/2021/07/cassandra_cannot_achieve_local_one-16x8.jpeg 16w" sizes="(max-width: 640px) 100vw, 640px" />

Cassandra login fails with: “Cannot achieve consistency level LOCAL_ONE”? Let’s see why it happens, and how to solve the problem Continue reading Cassandra login error: Cannot achieve consistency level LOCAL_ONE→