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Displaying posts with tag: Jervin Real (reset)
Profiling MySQL queries from Performance Schema

When optimizing queries and investigating performance issues, MySQL comes with built in support for profiling queries aka

SET profiling = 1;

 . This is already awesome and simple to use, but why the PERFORMANCE_SCHEMA alternative?

Because profiling will be removed soon (already deprecated on MySQL 5.6 ad 5.7); the built-in profiling capability can only be enabled per session. This means that you cannot capture profiling information for queries running from other connections. If you are using Percona Server, the profiling option for log_slow_verbosity is a nice alternative, unfortunately, not everyone is using Percona Server.

Now, for a quick demo: I execute a …

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Measuring the impact of tcpdump on Very Busy Hosts

A few years back Deva wrote about how to use tcpdump on very busy hosts. That post sparked my interest about exploring how to measure the impact of tcpdump on very busy hosts. In this post, I wanted to highlight how much of an impact there really is and what options you have to make the query collection much more effective.

Some things you need to know:

  • The test is a sysbench read-only workload, 8 tables, 8 threads, 1000000 rows each with 16G of buffer pool. Dataset fully in memory.
  • sysbench is ran on the same host, on 1Gbps connection, sysbench can saturate the network and therefore affect my network test with netcat so I decided to run locally.
  • There are 13 tests, 5 minutes each with 1 minute interval, varying on how the dump file is captured.
    • First one as …
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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 table with a few orphaned partitions and we will reconnect each partition one by one to the original table.

mysql [localhost] {msandbox} (recovery) > SHOW CREATE TABLE t1 G
*************************** 1. row ***************************
Table: t1
Create Table: CREATE TABLE `t1` (
KEY `h_date` (`h_date`)
/*!50100 PARTITION BY RANGE (year(h_date))
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Syncing MySQL slave table with pt-online-schema-change

I recently encountered a situation in which after running Percona Toolkit’s pt-table-checksum on a customer system, 95% of the table on the MySQL master was different on the MySQL slave. Although this table was not a critical part of the infrastructure, from time to time, writes to the table from the master would break replication. Additionally, this table has about 6 million rows, and running pt-table-sync would take sometime. Rebuilding the slave from backup of the master would not be an easy option as well since the slave acts as an archive where it has a lot more data than the master.

So how did we solve it? With pt-online-schema-change and a NOOP ALTER.

pt-online-schema-change --alter 'ENGINE=INNODB' D=dbname,t=tblname

How is it …

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High Availability with mysqlnd_ms on Percona XtraDB Cluster

This is the second part of my series on High Availability with mysqlnd_ms. In my first post, “Simple MySQL Master HA with mysqlnd_ms,” I showed a simple HA solution using asynchronous MySQL replication. This time we will see how to leverage an all-primary cluster where you can write to all nodes. In this post I used Percona XtraDB Cluster, but you should also be able to do the same with MySQL NDB Cluster or Tungsten Replicator.

To start with, here is the mysqlnd_ms configuration I used:


.  All of these files are available from my Github repository. Below, I have three Percona XtraDB Cluster nodes, …

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Encrypted and incremental MySQL backups with Percona XtraBackup

We’ve recently received a number of questions on how to implement incremental MySQL backups alongside encryption with Percona XtraBackup. Some users thought it was not initially possible because with the default


options with XtraBackup, all files will be encrypted, but alas, that is not the case. This is where the option


becomes useful, because it allows you to save LSN (Log Sequence Number) information to another directory and exclude it from encryption, allowing you to use the same information needed by incremental backups. Enough talk, let me show you.

Because you would want to usually script your backup and restore procedure, I’d use variables here as well to make you more familiar. First, I’d create 3 folders, where my backups will be stored, ‘full’ for full backups, ‘incr’ …

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keepalived with reader and writer VIPs for Percona XtraDB Cluster

This is a followup to Jay Janssen’s October post, “Using keepalived for HA on top of Percona XtraDB Cluster.” We got a request recently where the customer has 2 VIPs (Virtual IP addresses), one for reader and one for a writer for a cluster of 3 nodes. They wanted to keep it simple, with low latency and does not require an external node resource like HaProxy would.

keepalived is a simple load balancer with HA capabilities, which means it can proxy TCP services behind it and at the same time, keep itself highly available using VRRP as failover mechanism. This post is about taking advantage of the …

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Follow these basics when migrating to Percona XtraDB Cluster for MySQL

Galera/Percona XtraDB Cluster (PXC) for MySQL is a hot thing right now and some users jump right in without enough testing. Consequently, they’re more likely to either suffer failure or issues that prevent them from moving forward. If you are thinking of migrating your workload to Percona XtraDB Cluster, make sure to go through these basics.

log_slave_updates is REQUIRED

You need to have log_slave_updates enabled on the cluster node acting as async slave for replicated events from the async master to be applied to the other nodes, that is if you have more than one PXC node. This is because before Galera can create writesets for the replicated events, binlog events must be generated for the transactions first. Under …

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Showing entries 1 to 8