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Virident vCache vs. FlashCache: Part 2

May 17, 2013 By Ernie Souhrada 3 Comments

This is the second part in a two-part series comparing Virident’s vCache to FlashCache. The first part was focused on usability and feature comparison; in this post, we’ll look at some sysbench test results. Disclosure: The research and testing conducted for this post were sponsored by Virident. First, some background information. All tests were conducted [...]

Filed Under: Benchmarks, Hardware and Storage, MySQL Tagged With: Benchmarks, Ernie Souhrada, FlashCache, MLC, PCIe, sysbench, vCache, Virident

Benchmarking Percona Server TokuDB vs InnoDB

May 7, 2013 By Vadim Tkachenko 29 Comments

After compiling Percona Server with TokuDB, of course I wanted to compare InnoDB performance vs TokuDB. I have a particular workload I’m interested in testing – it is an insert-intensive workload (which is TokuDB’s strong suit) with some roll-up aggregation, which should produce updates in-place (I will use INSERT .. ON DUPLICATE KEY UPDATE statements [...]

Filed Under: Benchmarks, MySQL, Percona Server Tagged With: Benchmarking, InnoDB, Percona Server, TokuDB

MySQL Backup tools used by Percona Remote DBA for MySQL

March 13, 2013 By Ryan Huddleston 8 Comments

As part of Percona Remote DBA for MySQL service we recognize that reliable backups are one of the most important things we can bring to the table. In my experience handling emergencies, the single worst thing that can happen is finding out you don’t have backups available when some sort of data loss or catastrophic [...]

Filed Under: Cloud and NoSQL, Insight for DBAs, Insight for Developers, MySQL Tagged With: Amazon S3, data loss, database outage, database performance, MySQL, MySQL Backup tools, Percona Remote DBA, Percona XtraBackup, Rryan Huddleston

InnoDB Full-text Search in MySQL 5.6 (part 1)

February 26, 2013 By Ernie Souhrada 1 Comment

I’ve never been a very big fan of MyISAM; I would argue that in most situations, any possible advantages to using MyISAM are far outweighed by the potential disadvantages and the strengths of InnoDB. However, up until MySQL 5.6, MyISAM was the only storage engine with support for full-text search (FTS). And I’ve encountered many [...]

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: Ernie Souhrada, FTS, FullText Search, InnoDB, MyISAM, MySQL 5.6

Percona XtraDB Cluster – installation and setup webinar follow up Q&A

October 28, 2012 By Peter Boros 4 Comments

Thanks for all, who attended my webinar, I got many questions and I wanted to take this opportunity to answer them. Q: Even ntp has a delay of 0.3-0.4 between servers does that mean a 0.25 as from logs can be an issue ? A: My demo vms were running for a few hours before [...]

Filed Under: MySQL, XtraDB Cluster

Full Text Search Webinar Questions Followup

August 24, 2012 By Bill Karwin 5 Comments

I presented a webinar this week to give an overview of several Full Text Search solutions and compare their performance. Even if you missed the webinar, you can register for it, and you’ll be emailed a link to the recording. During my webinar, a number of attendees asked some good questions. Here are their questions and my [...]

Filed Under: Events and Announcements, Insight for Developers, MySQL

MySQL Indexing Best Practices: Webinar Questions Followup

August 16, 2012 By Peter Zaitsev 4 Comments

I had a lot of questions on my MySQL Indexing: Best Practices Webinar (both recording and slides are available now) We had lots of questions. I did not have time to answer some and others are better answered in writing anyway. Q: One developer on our team wants to replace longish (25-30) indexed varchars with [...]

Filed Under: Insight for DBAs, MySQL

Innodb Table Locks

July 31, 2012 By Peter Zaitsev 4 Comments

Innodb uses row level locks right ? So if you see locked tables reported in SHOW ENGINE INNODB STATUS you might be confused and rightfully so as Innodb table locking is a bit more complicated than traditional MyISAM table locks. Let me start with some examples. First lets run SELECT Query:

---TRANSACTION 12303, ACTIVE 26 sec
mysql tables in use 2, locked 0
MySQL thread id 53038, OS thread handle 0x7ff759b22700, query id 3918786 localhost root Sending data
select count(*) from sbtest,sbtest x
Trx read view will not see trx with id >= 12304, sees < 12301

---TRANSACTION 12303, ACTIVE 26 sec

mysql tables in use 2, locked 0

MySQL thread id 53038, OS thread handle 0x7ff759b22700, query id 3918786 localhost root Sending data

select count(*) from sbtest,sbtest x

Trx read view will not see trx with id >= 12304, sees < 12301

As you can [...]

Filed Under: Insight for DBAs, MySQL

How to diagnose errors in the MySQL error log

March 26, 2012 By Baron Schwartz 4 Comments

I frequently see questions about how to understand the nature of errors in MySQL’s error log. Now, there is a lot of complexity to this — the flowchart would be quite large, as with any nontrivial piece of software. But there is one particular class of errors that is relatively easy to diagnose, if you [...]

Filed Under: Insight for DBAs, Percona Software

Checking the subset sum set problem with set processing

May 16, 2011 By Justin Swanhart Leave a Comment

Hi, Here is an easy way to run the subset sum check from SQL, which you can then distribute with Shard-Query:

CREATE TABLE `the list` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `val` bigint(20) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`),
  KEY `id` (`id`)
) ENGINE=MyISAM;
SELECT val as `val`, COUNT(DISTINCT (id)) as `cd`
FROM  test.data as d  WHERE val in (-2,-3,-10,15,15,16)
GROUP BY val;
+-----+----------+----------+
| val | cd       | CNT      |
+-----+----------+----------+
| -10 |        1 |        1 |
|  -3 |        1 |        1 |
|  -2 |        1 |        1 |
|  15 | 35417088 | 35417088 |
+-----+----------+----------+
5 rows in set (40.20 sec)

CREATE TABLE `the list` (

`id` bigint(20) NOT NULL AUTO_INCREMENT,

`val` bigint(20) NOT NULL DEFAULT '0',

PRIMARY KEY (`id`),

KEY `id` (`id`)

) ENGINE=MyISAM;

SELECT val as `val`, COUNT(DISTINCT (id)) as `cd`

FROM test.data as d WHERE val in (-2,-3,-10,15,15,16)

GROUP BY val;

+-----+----------+----------+

| val | cd | CNT |

+-----+----------+----------+

| -10 | 1 | 1 |

| -3 | 1 | 1 |

| -2 | 1 | 1 |

| 15 | 35417088 | 35417088 |

+-----+----------+----------+

5 rows in set (40.20 sec)

Notice there is no 16 in the list. We did not pass the check. There are enough 15s though. The distinct value count for each item in the output set, must at least [...]

Filed Under: MySQL

Virident vCache vs. FlashCache: Part 2

Benchmarking Percona Server TokuDB vs InnoDB

MySQL Backup tools used by Percona Remote DBA for MySQL

InnoDB Full-text Search in MySQL 5.6 (part 1)

Percona XtraDB Cluster – installation and setup webinar follow up Q&A

Full Text Search Webinar Questions Followup

MySQL Indexing Best Practices: Webinar Questions Followup

Innodb Table Locks

How to diagnose errors in the MySQL error log

Checking the subset sum set problem with set processing

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