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Closed 10 years ago.
I have basic knowledge in mysql. But I want more. I mean, "If I enter a query, how was the mysql server processing it and put the result", like that.
What I exactly want, how does mysql server read .frm file?
Anyone refer me the link for that. Thank you in advance.
You will need to look into the Execution plan to know how the RDBMS works internally, try this as a starting point: Understanding the Query Execution Plan
Everytime you try writing a query, just issue the following command and see
Explain <select statement>
This by default gives you the elaborate details of what is going to happen when you actually execute a query. Very helpful in debugging as well as improving the performance of queries.
Try to get information from below link
http://ece.ut.ac.ir/dbrg/seminars/AdvancedDB/Fall%202008/hashemi/Project_MySQL_Benchmark/References/MySQL%20Conceptual%20Architecture.pdf
Related
It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.
Closed 10 years ago.
I want to use a <textarea> tag or an alternative written in JavaScript, that highlights my SQL statements as I write them (effectively the same as phpMyAdmin's SQL section where you can manually write queries.)
Please tell me that this is possible without using HUGE libraries and can be easily customizable. If so, which library should I be using and how?
http://codemirror.net/
I think I found what I wanted. Though this looks like a big library, this will do the trick. Thanks everybody.
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Closed 10 years ago.
I need to do some analysis of table usage within my MySQL system. Can anyone point me in the right direction on a method for identifying which table has been queried most often in a given time-period i.e. if there are 30 tables, I want to know which table is accessed most.
You should use pt-table-usage to analyze the general query log. It will out put nice information about table usage (as long as you're not using stored procedures or stored functions cause those will be missed).
Enable query logging temporarily while your application is running and review the log. It can have some performance impact, so you don't want to leave it permanently enabled.
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Closed 11 years ago.
i wanted to ask a question that i myself have been asked in class by our database teacher;
What makes MySQL different from other Sqls? I've always been using MySQL due to the fact that's what we have been taught when i learned how to program websites, but honestly? I dont know what makes MySQL better then other SQL's(For program development) such as;
SQLite
MS Access
PostgreSQL
MongoDB
I was hoping someone could point me towards the answer or perhaps even give me a explanation of it.
I hope it was alright to post this question here as i'm unsure as to were else it should have been posted.
I'd choose MySQL over
SQLite, because SQLite is too "lite" for a lot of purposes; it does not have multi-user access, so would not work quite well in server environment
MS Access and PostgreSQL, because they are less common and I'm more likely to get useful community support for them (especially valid for MS Access :-)
MongoDB, because that is not SQL database at all, and you've asked about SQL databases
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Closed 11 years ago.
There is couple of these already. My question though is how can something like this happen? is it cause by a bug in my code or is it an apache related problem?
Invalid query: Incorrect key file for table '/tmpfs/#sql_8e2_1.MYI'; try to repair it
Which version of mysql are you running? Are there open bugs which could cause this problem with the version you're running? Did the server lose power or crash?
Consider using the repair table syntax:
http://dev.mysql.com/doc/refman/5.1/en/repair-table.html
Please note all the warnings about making backups before running this.
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Closed 9 years ago.
How to optimize queries which are already written?
Use EXPLAIN to see what's going on - what indexes are being used and so on.
If you can not change the them:
Indexes and statistics.
So you don't optimize the query but their execution plan.
If you can't change the query then it really depends on what features are available on your database engine of choice. As Ovidiu said you can use indexes and generate usage statistics to see where the bottleneck is.
Otherwise you can employ techniques like materialised views or horizontal partitioning.
Before you start make sure you know what you're optimisation target is.
IBM Informix Dynamic Server supports a feature that allows you to add optimizer directives to pre-existing SQL when it is executed (without modifying the application). Look up 'external directives' at the Informix web site for more information (or Google 'site:ibm.com informix external directives').