Search Results for: select * from table where or

MySQL indexing 101: a challenging single-table query

We discussed in an earlier post how to design indexes for many types of queries using a single table. Here is a real-world example of the challenges you will face when trying to optimize queries: two similar queries, but one is performing a full table scan while the other one is using the index we […]

Indexing 101: Optimizing MySQL queries on a single table

I have recently seen several cases when performance for MySQL queries on a single table was terrible. The reason was simple: the wrong indexes were added and so the execution plan was poor. Here are guidelines to help you optimize various kinds of single-table queries. Disclaimer: I will be presenting general guidelines and I do […]

How well does your table fit in the InnoDB buffer pool in MySQL 5.6+?

Some time ago, Peter Zaitsev posted a blog titled “How well does your table fits in innodb buffer pool?” He used some special INFORMATION_SCHEMA tables developed for Percona Server 5.1 to report how much of each InnoDB table and index resides in your buffer pool. As Peter pointed out, you can use this view into […]

MySQL 5.6 Transportable Tablespaces best practices

In MySQL 5.6 Oracle introduced a Transportable Tablespace feature (copying tablespaces to another server) and Percona Server adopted it for partial backups which means you can now take individual database or table backups and your destination server can be a vanilla MySQL server. Moreover, since Percona Server 5.6, innodb_import_table_from_xtrabackup is obsolete as Percona Server also […]

Data inconsistencies on MySQL replicas: Beyond pt-table-checksum

Percona Toolkit’s pt-table-checksum is a great tool to find data inconsistencies between a MySQL master and its replicas. However it is sometimes not enough to know that there are inconsistencies and let pt-table-sync fix the issue: you may want to know which exact rows are different to identify the statements that created the inconsistency. This […]

Recover orphaned InnoDB partition tablespaces in MySQL

A few months back, Michael wrote about reconnecting orphaned *.ibd files using MySQL 5.6. I will show you the same procedure, this time for partitioned tables. An InnoDB partition is also a self-contained tablespace in itself so you can use the same method described in the previous post. To begin with, I have an example […]

When (and how) to move an InnoDB table outside the shared tablespace

In my last post, “A closer look at the MySQL ibdata1 disk space issue and big tables,” I looked at the growing ibdata1 problem under the perspective of having big tables residing inside the so-called shared tablespace. In the particular case that motivated that post, we had a customer running out of disk space in his […]

TokuDB gotchas: slow INFORMATION_SCHEMA TABLES

We are using Percona Server + TokuDB engine extensively in Percona Cloud Tools and getting real usage operational experience with this engine. So I want to share some findings we came across, in hope it may help someone in their work with TokuDB. So, one problem I faced is that SELECT * FROM INFORMATION_SCHEMA.TABLES is […]

Why ALTER TABLE runs faster on Percona Server 5.5 vs. MySQL 5.5

Some of us Perconians are at OpenStack summit this week in Atlanta. Matt Griffin, our director of product management, tweeted about the turbo-hipster CI talk about their experience of ALTER TABLEs running faster on Percona Server. Oracle’s Morgan Tocker then tweeted in response, asking why this was the case. I decided that the simplest way to […]

How to monitor ALTER TABLE progress in MySQL

While working on a recent support issue as a Percona Support Engineer,  I got one question from a customer asking how to monitor ALTER TABLE progress. Actually, for MySQL 5.5 and prior versions, it’s quite difficult to ALTER the table in a running production environment especially for large tables (with millions records). Because it will rebuild and lock the table […]