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Search Results for: mysql php concurrent queries

MySQL Error: Too many connections

We have always received quite few questions here at Percona Support on how to avoid the dreaded “Too many connections” error, as well as what is the recommended value for max_connections. So, in this article …


trx descriptors: MySQL performance improvements in Percona Server 5.5.30-30.2

One major problem in terms of MySQL performance that still stands in the way of InnoDB scalability is the trx_list scan on consistent read view creation. It was originally reported as a part of MySQL …


Shard-Query adds parallelism to queries

Preamble: On performance, workload and scalability: MySQL has always been focused on OLTP workloads. In fact, both Percona Server and MySQL 5.5.7rc have numerous performance improvements which benefit workloads that have high concurrency. Typical OLTP …


When would you use SAN with MySQL ?

One question which comes up very often is when one should use SAN with MySQL, which is especially popular among people got used to Oracle or other Enterprise database systems which are quite commonly deployed …


iiBench Contest – Who Can Insert 1B Rows into MYSQL the Fastest?

At the recent OpenSQL Camp in Charlottesville, VA, Tokutek offered a challenge to the MySQL community – who can insert a billion rows into MySQL the fastest?  We will post the results on our website …


MySQL File System Fragmentation Benchmarks

Few days ago I wrote about testing writing to many files and seeing how this affects sequential read performance. I was very interested to see how it shows itself with real tables so I’ve got …


MySQL Error Message Nonsenses

What MySQL honestly was never good at is giving good helpful error messages. Start with basics for example – The error message in case of syntax error gives you information about tokens near by but …


MySQL Quality of old and new features

Recent couple of days our team was pointed to number of bugs in MySQL 5.0 which again seriously shakes the confidence in both MySQL Quality Control and bug fix promptness. Let me just take couple …


MySQL 4 to MySQL 5 Upgrade performance regressions

This week I already had two serious performance regression cases when upgrading from MySQL 4.0 and 4.1 to MySQL 5.0. By serious I mean several times performance difference not just 5-10% you often see for …


Are PHP persistent connections evil ?

As you probably know PHP “mysql” extension supported persistent connections but they were disabled in new “mysqli” extension, which is probably one of the reasons some people delay migration to this extension. The reason behind …