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10 Newer Entries Showing entries 61 to 70 of 825 10 Older Entries

Displaying posts with tag: performance (reset)

Galera Cluster for MySQL vs MySQL (NDB) Cluster: A High Level Comparison - Webinar Replay & Slides
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Thanks to everyone who attended and participated in last week’s webinar on 'Galera Cluster for MySQL vs MySQL (NDB) Cluster: A High Level Comparison'. If you missed the sessions or would like to watch the webinar again & browse through the slides, they are now available online.

 

In this webinar, Severalnines VP of Products, Alex Yu, who was part of the team at Ericsson who originally developed the NDB storage engine in 2001, gave an overview of the two clustering architectures and discussed their respective strengths and weaknesses: 

  1. MySQL …
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Some Notes on Index Statistics in InnoDB
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In MySQL 5.6 we introduced a huge improvement in the way that index and table statistics are gathered by InnoDB and subsequently used by the Optimizer during query optimization: Persistent Statistics. Some aspects of the way that Persistent Statistics work could be improved further though, and we’d really like your input on that.

How much to sample?

The statistics are gathered by picking some pages semi-randomly, analyzing …

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MySQL-Oslayer-Performance-Optimization
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upload on 2014.12 [ten important tips of MySQL database design for better performance] Download this PDF

What is stuck in MySQL server?
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There are few easy ticks to see what is stuck inside MySQL instance. All these techniques will not give you whole picture, but might help to find queries that block performance. Let’s start from what exactly doing your MySQL server right now.

Which queries are running now?

This will give you an idea what’s running right now so you can find long running queries which slowing down MySQL and/or causing replication lag:

mysql -e "SHOW PROCESSLIST" | grep -v -i "sleep"

It is more convenient than just run “SHOW PROCESSLIST” as it’s hiding all connected threads in “Sleep” state so you’ll get a clean output. Also you can get …

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Performance Schema memory tables and rightless users
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When I talk about troubleshooting I like to repeat: "Don't grant database access to everybody!" This can sound a bit weird having one can give very limited read-only access.

But only if ignore the fact what even minimal privileges in MySQL allows to change session variables, including those which control server resources. My favorite example is "Kill MySQL server with join_buffer_size". But before version 5.7 I could only recommend this, but not demonstrate. Now, with help of memory summary tables in Performance Schema, I can show how unprivileged user can let your server to use great amount of swap.

At first lets …



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Full table scans and MySQL performance
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High season is coming, how do you make sure that MySQL will handle the increased load? Stress tests could help with that, but it’s not a good idea to run them in a production environment. In this case Select_scan, Select_full_join and other MySQL counters could quickly give you an idea of how many queries are not performing well and could cause a performance degradation as the load goes up.

Select_scan from SHOW GLOBAL STATUS indicates how many full table scans were done since last MySQL restart. Scanning the entire table is a resource intensive operation. It also forces MySQL to store unnecessary data in the buffer pool, wasting memory and IO …

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9 DevOps Tips for Going in Production with Galera Cluster for MySQL - Webinar Replay & Slides
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November 14, 2014 By Severalnines

Thanks to everyone who attended and participated in this week's webinar on '9 DevOps Tips for Going in Production with Galera Cluster for MySQL'. If you missed the sessions or would like to watch the webinar again & browse through the slides, they are now available online.

 

In this webinar, Severalnines CTO Johan Andersson discussed 9 key aspects to consider before taking Galera Cluster for MySQL into production:

  • 101 Sanity Check
  • Operating System
  • Backup Strategies
  • Galera Recovery
  • Query …
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Preliminary MySQL Cluster benchmark results on POWER8
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Yesterday, I got the basics going for MySQL Cluster on POWER. Today, I finished up a couple more patches to improve performance and ran some benchmarks.

This is on a 3.7Ghz POWER8 machine with non-balanced memory (only 2 of the 4 NUMA nodes have memory, so we have less total memory bandwidth than we could have, plus I’m going to bind ndbmtd to the CPUs in these NUMA nodes)

With a setup of a single replica and two data nodes on the one machine (each bound to a specific NUMA node), running the flexAsync benchmark …

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SSD All The Things
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After some grueling IO testing on 7200rpm disks, I got my hands on some shiny new Samsung 840 SSDs and wanted to share the performance results in similar fashion.

Dell r630, E5-2630 v3 @ 2.40GHz (16 cores), 256GB RAM, Samsung 840 EV SSD 960GB.

Testing was sysbench, fileio-rndrw, async+direct io, 16 threads, 5.5TB RAID-6 using XFS mounted with noatime,inode64 and using the deadline scheduler.

Write Policy Read Policy xfs options Transfer/s Requests/s Avg/Request
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Removing Scalability Bottlenecks in the Metadata Locking and THR_LOCK Subsystems in MySQL 5.7
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The MySQL Server 5.7.5 Development Milestone Release, which was published recently, contains some significant changes to the metadata locking (MDL) subsystem and to the usage of the THR_LOCK manager for InnoDB tables. This post provides more information about these changes, which resulted in nice improvements in both scalability and performance.

Sometime during the development cycle of MySQL 5.6 we realized that locks used in the metadata locking subsystem (MDL) implementation can become a …

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10 Newer Entries Showing entries 61 to 70 of 825 10 Older Entries

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