Applications in our company were working on quite old Apache + MySQL bundle (with PHP 5.x) but they were fast in retrieving data from the database. Simple retrieval of around 100 rows with some basic calculations would take around a second or two.
We had that bundle upgraded to the newest XAMPP version and all features it comes with. Applications were not changed (they did not have to, they just retrieve data and calculate them) but the performance of the very same operations has lowered significantly, they take around 20 seconds, sometimes up to 50 seconds.
I would appreciate it if anybody could point me to what can be done to improve the performance on that new bundle.
Thank you in advance.
In case anyone ever experiences this error, your my.ini needs some improvements on the size of cache and buffer. There's a working version of my.ini available if you search it on Google. It worked like a miracle in terms of MySQL performance.
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I have just moved a WP installation from one hosting provider to another. Everything went fine except for a problem I have with the new installation. Please note that I have moved from a regular VPS to a kinda powerful and fast dedicated machine.
The thing is that now, the website is slower than when in the previous server. It takes 6-7 seconds to load a page and according to Chrome's Dev Tools network panel, it has a period of 3-4 seconds to the get the first response byte (TTFB), which is insane.
I have tried the following with no success:
Review database for anomalies
Disable all plugins (and delete them)
Disable template (and delete it)
With these last two actions, I lowered the loading time to 5-6 seconds, which is a lot for small site (a few hundreds of posts and 50-60 pages), with no comments enabled. I still have the 3-4 TTFB period.
After that, I installed the Query Monitor plugin and found out that, at every page load, WP performs hundreds (ranging from 400 to 800) database queries and, in some cases, even 1500 database queries. OMG!
Honestly, I am quite lost here. I mean, on one hand I have this strange database behavior I cannot really understand. And on the other hand, I cannot help wondering how it was faster on the previous & slower server.
By the way, I have moved from MySQL to MariaDB, which should be even faster too. Indexes are kept when dumping & importing the file. I am lost. :(
Any help is greatly appreciated. Apologies for my english (not my language) and please let me know if the is some important information missing. I will be glad to provide all the necessary information that help me/us troubleshoot this.
Thanks in advance!
I think you should optimize your MySQL config (my.cnf in Linux or my.ini in Windows). To view problems in MySQL you can try run the script MySQLTuner: https://github.com/major/MySQLTuner-perl.
I have recently upgraded a system from mysql5.6 to mysql5.7 and I am experienceing significant lose of speed in the app.
Beside going over the available config values one by one and learn them + tweka them, Is there a way to identify/ debug the problem?
Google will give me info on how to use the slow query log, but that wont help, a I am not debugging a specific slow query, but rather a slownes that settms maybe from bad installation/configuration of the entire DB.
I'm not sure if caching would be the correct term for this but my objective is to build a website that will be displaying data from my database.
My problem: There is a high probability of a lot of traffic and all data is contained in the database.
My hypothesized solution: Would it be faster if I created a separate program (in java for example) to connect to the database every couple of seconds and update the html files (where the data is displayed) with the new data? (this would also increase security as users will never be connecting to the database) or should I just have each user create a connection to MySQL (using php) and get the data?
If you've had any experiences in a similar situation please share, and I'm sorry if I didn't word the title correctly, this is a pretty specific question and I'm not even sure if I explained myself clearly.
Here are some thoughts for you to think about.
First, I do not recommend you create files but trust MySQL. However, work on configuring your environment to support your traffic/application.
You should understand your data a little more (How much is the data in your tables change? What kind of queries are you running against the data. Are your queries optimized?)
Make sure your tables are optimized and indexed correctly. Make sure all your query run fast (nothing causing a long row locks.)
If your tables are not being updated very often, you should consider using MySQL cache as this will reduce your IO and increase the query speed. (BUT wait! If your table is being updated all the time this will kill your server performance big time)
Your query cache is set to "ON". Based on my experience this is always bad idea unless your data does not change on all your tables. When you have it set to "ON" MySQL will cache every query. Then as soon as they data in the table changes, MySQL will have to clear the cached query "it is going to work harder while clearing up cache which will give you bad performance." I like to keep it set to "ON DEMAND"
from there you can control which query should be cache and which should not using SQL_CACHE and SQL_NO_CACHE
Another thing you want to review is your server configuration and specs.
How much physical RAM does your server have?
What types of Hard Drives are you using? SSD is not at what speed do they rotate? perhaps 15k?
What OS are you running MySQL on?
How is the RAID setup on your hard drives? "RAID 10 or RAID 50" will help you out a lot here.
Your processor speed will make a big different.
If you are not using MySQL 5.6.20+ you should consider upgrading as MySQL have been improved to help you even more.
How much RAM does your server have? is your innodb_log_buffer_size set to 75% of your total physical RAM? Are you using innodb table?
You can also use MySQL replication to increase the read sources of the data. So you have multiple servers with the same data and you can point half of your traffic to read from server A and the other half from Server B. so the same work will be handled by multiple server.
Here is one argument for you to think about: Facebook uses MySQL and have millions of hits per seconds but they are up 100% of the time. True they have trillion dollar budget and their network is huge but the idea here is to trust MySQL to get the job done.
One of the projects I'm working on is suffering from a recent slowdown in the DB (since last week).
Code hasn't changed, data may have changed a little but not significantly so at this stage I'm just exploring DB configuration (as we are on a managed hosting platform, end have had some similar issues in the past).
Unfortunately I'm out of my depth a bit... could anyone please take a look at the output from SHOW STATUS below and see if any of it sets alarm bells off? The only thing I've spotted so far is that key_reads vs key_read_requests don't seem quite right.
Our setup is 2 servers replicated, with all reads done from the slave. Queries which run in 0.01 secs on the master are taking up to 7 secs on the slave... and this has only started recently.
All tables are MyIsam and inserts/updates are negligible (updates happen out of hours). Front end is an ASP .NET website (.NET 4) running on IIS8 with a devart component for data access.
Thanks!
SHOW STATUS output is here: http://pastebin.com/w6xDeD48
Other factors can impact MySQL performance:
virus scanning software -> I had a issue with McAfee bogging out peformance due to it scanning temporary table files
Other services running on server?
Have you tried a EXPLAIN SELECT on the query? This would given you an indication of the index size. As #Liath indicated the indexes may be out of date on the slave but find on the master.
Just an update in case it ever helps anyone else in future - it looks like the culprit might be the query cache for now, as we are seeing better performance with it turned off (still not quite as good as we had before the issue).
So we will try to tune it a little and get back to great performance!
We had an applicationg running using MySql. We found MySql was not suitable for our app after we found that it didnt support some of the GIS capability that PostGIS has (note: mysql only supports minimum-bounding rectangle GIS search).
So we changed our DB to PostgreSQL. We then found out that Postgresql 8.2 running on Windows is so much slower compared to Mysql 5.1. By slower, I mean at roughly 4-5 times slower.
Why is this? Is there something in the configuration that we need to change?
I found some comments from other websites such as this:
UPDATE: We found that the cause of the slowness is due to the BLOB that we are inserting into the DB. We need to be able to insert BLOB at a sustained rate of 10-15 MB/s. We are using libpq's lo_read and lo_write for each BLOB we are inserting/reading. Is that the best way? Has anyone used Pgsql for inserting large BLOB at a high rate before?
EDIT: I heard that PgSql just recently got ported to Windows. Could this be one of the reasons?
There are cases where PostgreSQL on Windows pays an additional overhead compared to other solutions, due to tradeoffs made when we ported it.
For example, PostgreSQL uses a process per connection, MySQL uses a thread. On Unix, this is usually not a noticeable performance difference, but on Windows creating new processes is very expensive (due to the lack of the fork() system call). For this reason, using persistent connections or a connection pooler is much more important on Windows when using PostgreSQL.
Another issue I've seen is that early PostgreSQL on Windows will by default make sure that it's writes are going through the write cache - even if it's battery backed. AFAIK, MySQL does not do this, and it will greatly affect write performance. Now, this is actually required if you have a non-safe hardware, such as a cheap drive. But if you have a battery-backed write cache, you want to change this to regular fsync. Modern versions of PostgreSQL (certainly 8.3) will default to open_datasync instead, which should remove this difference.
You also mention nothing about how you have tuned the configuration of the database. By default, the configuration file shipped with PostgreSQL is very conservative. If you haven't changed anything there, you definitely need to take a look at it. There is some tuning advice available on the PostgreSQL wiki.
To give any more details, you will have to provide a lot more details about exactly what runs slow, and how you have tuned your database. I'd suggest an email to the pgsql-general mailinglist.
While the Windows port of PostgreSQL is relatively recent, my understanding is that it performs about as well as the other versions. But it's definitely a port; almost all developers work primarily or exclusively on Unix/Linux/BSD.
You really shouldn't be running 8.2 on Windows. In my opinion, 8.3 was the first Windows release that was truly production-ready; 8.4 is better yet. 8.2 is rather out of date anyway, and you'll reap several benefits if you can manage to upgrade.
Another thing to consider is tuning. PostgreSQL requires more tuning than MySQL to achieve optimal performance. You may want to consider posting to one of the mailing lists for help with more than basic tweaking.
PostgreSQL is already slower than MySQL up to a certain point (it is actually faster when you have a ridiculously large database). Just FYI, this isn't causing your problem but keep that in mind.