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Query_cache and column level privileges

 | August 6, 2007 |  Posted In: Insight for Developers

Recently we were puzzled by question how query_cache works with column level privileges. The question was appeared as we discovered function query_cache_send_result_to_client is called before real parsing of query, so at the moment of execution the query_cache is not able to know which columns are accessed. Looking into source code I found out that in […]

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Beware large Query_Cache sizes

 | March 23, 2007 |  Posted In: Insight for DBAs

During last couple of months I had number of consulting projects with MySQL Query Cache being source of serious problems. One would see queries both for MyISAM and Innodb tables mysteriously stalling for few seconds with “NULL” in State column. These could be troubleshooted to waiting on Query Cache which at the same time had […]

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ProxySQL Query Cache: What It Is, How It Works

 | February 7, 2018 |  Posted In: Insight for DBAs, MySQL, ProxySQL

ProxySQL query cache

In this blog post, I’ll present the ProxySQL query cache functionality. This is a query caching mechanism on top of ProxySQL. As there are already many how-tos regarding the ProxySQL prerequisites and installation process, we are going to skip these steps. For those who are already familiar with ProxySQL query cache configuration, let’s go directly […]

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Does the Meltdown Fix Affect Performance for MySQL on Bare Metal?

and  | January 18, 2018 |  Posted In: Insight for DBAs, Insight for Developers, MySQL, Security

Meltdown Fix Affect Performance small

In this blog post, we’ll look at does the Meltdown fix affect performance for MySQL on bare metal servers. Since the news about the Meltdown bug, there were a lot of reports on the performance hit from proposed fixes. We have looked at how the fix affects MySQL (Percona Server for MySQL) under a sysbench workload. […]

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MySQL, Percona Server for MySQL and MariaDB Default Configuration Differences

 | October 9, 2017 |  Posted In: InnoDB, Insight for DBAs, MariaDB, MySQL

MySQL and MariaDB Default Configuration

In this blog post, I’ll discuss some of the MySQL and MariaDB default configuration differences, focusing on MySQL 5.7 and MariaDB 10.2. Percona Server for MySQL uses the same defaults as MySQL, so I will not list them separately. MariaDB Server is a general purpose open source database, created by the founders of MySQL. MariaDB […]

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Percona Monitoring and Management 1.1.2 is Now Available

 | April 3, 2017 |  Posted In: Database Monitoring, Events and Announcements, MariaDB, MongoDB, MySQL, Orchestrator, Percona Monitoring and Management, Percona Software, PMM, ProxySQL

Percona Monitoring and Management

Percona announces the release of Percona Monitoring and Management 1.1.2 on April 3, 2017. For installation instructions, see the Deployment Guide. This release includes several new dashboards in Metrics Monitor, updated versions of software components used in PMM Server, and a number of small bug fixes.

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A Look at MariaDB Subquery Cache

 | March 2, 2017 |  Posted In: MariaDB, MySQL

MariaDB Subquery Cache

The MariaDB subquery cache feature added in MariaDB 5.3 is not widely known. Let’s see what it is and how it works. What is a subquery cache? The MariaDB subquery cache optimizes the execution of correlated subqueries. Correlated subqueries refer to a value from the parent query. For example:

MariaDB only uses this optimization if […]

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Millions of Queries per Second: PostgreSQL and MySQL’s Peaceful Battle at Today’s Demanding Workloads

and  | January 6, 2017 |  Posted In: Benchmarks, InnoDB, MySQL, open source databases, OpenSource Databases on big machines, Percona Live

PostgreSQL and MySQL

This blog compares how PostgreSQL and MySQL handle millions of queries per second. Anastasia: Can open source databases cope with millions of queries per second? Many open source advocates would answer “yes.” However, assertions aren’t enough for well-grounded proof. That’s why in this blog post, we share the benchmark testing results from Alexander Korotkov (CEO of […]

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Is Your Query Cache Really Disabled?

and  | November 11, 2016 |  Posted In: MySQL

Query Cache

This blog post was motivated by an internal discussion about how to fully disable query cache in MySQL. According to the manual, we should be able to disable “Query Cache” on the fly by changing query_cache_type to 0, but as we will show this is not fully true. This blog will show you how to properly disable “query […]

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