I read the following article yesterday (http://blogs.sitepoint.com/2010/11/19/mysql-mistakes-php-developers/) and it wrote the following:
MySQL has a number of database engines but you’re most likely to encounter MyISAM and InnoDB.
MyISAM is used by default. However, unless you’re creating a very simple or experimental database, it’s almost certainly the wrong choice! MyISAM doesn’t support foreign key constraints or transactions which are essential for data integrity. In addition, the whole table is locked whenever a record is inserted or updated: it causes a detrimental effect on performance as usage grows.
The solution is simple: use InnoDB.
I've always used MyISAM because it was the default. What do you think?
If I were to upgrade to InnoDB, in phpMyAdmin, can I just edit each table and change it to innoDB or is there a more complex process to perform?
Thanks!
Yes, you can swap in and out engines like used underwear, if you like, without much trouble. Just change it in phpmyadmin.
But I wouldn't change it for the sake of changing it. Do you need to use foreign keys? Change it. Do you need row-level-locking instead of table-locking? Change it.
It's worth noting that there are good reasons to use MyISAM, too. Take a look at FULLTEXT indexing. You can't do that with InnoDB.
UPDATE
As of MySQL 5.6 FULLTEXT has been implemented for InnoDB tables as well. Here is the manual.
Sorry for bumping an old question, but this also helped me a lot to choose which engine, especially since MyISAM is faster for reads and my database tables had more read the write:
http://www.rackspace.com/knowledge_center/article/mysql-engines-myisam-vs-innodb
Related
I read that Innodb is better to use on a table that get a lot's of insert records simultaneously. My application gets about 50 records per seconds. So for these tables should I use Innodb, right?
In the other hand i have some tables that are only used for select, they get few updated or have few new insert. Is MyIsam faster for select ?
If it's the case, is it better to leave some table with MyIsam and some with Innodb or should i use all tables with the same engine ?
My application also searches a lot on the tables that i want to pass in Innodb. What should i do ?
you can check these:
Reasons to use MyISAM:
Tables are really fast for select-heavy loads
Table level locks limit their scalability for write intensive multi-user environments.
Smallest disk space consumption
Fulltext index
Merged and compressed tables.
Reasons to use InnoDB:
ACID transactions
Row level locking
Consistent reads – allows you to reach excellent read write concurrency.
Primary key clustering – gives excellent performance in some cases.
Foreign key support.
Both index and data pages can be cached.
Automatic crash recovery – in case MySQL shutdown was unclean InnoDB tables will still
recover to the consistent state- No check repair like MyISAM may require. All updates have to pass through transactional engine in
InnoDB, which often decreases - performance compared to
non-transactional storage engines.
quoted from here
and for the last part:
REMEMBER! It's OK to mix table types in the same database! In fact it's recommended and frequently required. However, it is important to note that if you are having performance issues when joining the two types, try converting one to the other and see if that fixes it. This issue does not happen often but it has been reported.
quoted from here
I hope that's enough :D
Yes you can, but I'd go with InnoDB only unless there is some serious performance bottleneck
same question on SO
MySQL forum
In short yes you can mix and match to your hearts content.
Keep the following in mind:
InnoDB is ACID complaint. Thus is you need any ACID features use InnoDB. MyISAM is does not support a lot of things like foreign key constraints for example.
Now speed is hard to quantify exactly. Depending on execution paths you might get very big or very small speed differences.
Test and check there is no right or wrong answer here.
i'm Developing a large Website, and adding many functionalities on it. I want to know if there's any problem with making all the tables in the database InnoDB type, cuz there are so many foreign key connection within all the tables
I have like 20 tables in the database, and all the tables in the database are all connected together somehow, is there any problem with this, or it's okay, thanks.
InnoDB is preferred over MyISAM and if you have foreign key constraints then you should use InnoDB anyway since MyISAM doesn't support foreign keys.
Also, if you want to use InnoDB, its usually recommended that all tables use InnoDB. It provides a number of advantages anyway so I'd say yes, make all tables InnoDB unless you have a good reason not to (i.e. you need MyISAM Geospatial extensions or Fulltext and your InnoDB version doesn't support those features).
Nothing wrong with it at all, you should use whatever functionality is available to you such as the INNODB engine.
Problems, no. But what dbm are you using?
(InnoDB is the default storage engine for MySQL)
So there should be no problems, assuming you are using MySQL or any others that support InnoDB. but what are you doing with the tables and what would cause a problems, or that you think would cause problems ...
As far as I am aware the only non-trivial reason to choose MyISAM over InnoDB is for Full-Text indexing. Apart from that, InnoDB's support for transactions and foreign key constraints make it a much better choice for the vast majority of applications.
That said, there's nothing stopping you from using a few MyISAM tables alongside InnoDB tables if you require some functionality from MyISAM.
I'm running a django system over mysql in amazon's cloud, and the database default is innodb. But now I want to put a fulltext index on a couple of tables for searching, which evidently requires myisam.
The obvious solution is to just tell mysql to ALTER TABLE to myisam, but are there going to be any issues with that?
One that comes to mind is that I'll have to remember to do that any time I build a new version of the database, which should theoretically be rare, but there doesn't seem to be a way to tell django to please set the storage engine at the table level. I guess I could write a migration (we use south).
Any other things I might be missing? What could possibly go wrong?
Will the application notice? Probably not.
Will it cause problems? Only when things go wrong. MyISAM is not a transactional storage engine. If you change the data in a MyISAM table while inside of a transaction, then have to roll back changes, the changes in that table won't be rolled back. It's been a while since I tried to break it horribly, but I'm willing to wager that MySQL won't even issue a warning when this happens. This will lead to data consistency issues.
You should seriously consider external search software instead of a fulltext index, like ElasticSearch (integrates at the application level), or Sphinx (integrates at the MySQL level, though if you're using RDS instead of MySQL directly, I don't think you'll be able to use it).
the following may be of help:
use a myisam fulltext table to index back into your innodb tables for example:
Build your system using innodb:...
Any way to achieve fulltext-like search on InnoDB
I've read various threads about which is better between InnoDB and MyISAM. It seems that the debates are to use or the other. Is it not possible to use both, depending on the table?
What would be the disadvantages in doing this? As far as I can tell, the engine can be set during the CREATE TABLE command. Therefore, certain tables which are often read can be set to MyISAM, but tables that need transaction support can use InnoDB.
You can have both MyISAM and InnoDB tables in the same database. What you'll find though, when having very large tables is, MyISAM would cause table-lock issues. What this ultimately does is, it locks the whole table for a single transaction, which is very bad if you have many users using your website. e.g If you have a user searching for something on your site and the query takes minutes to complete, no other users could use your site during that period because the whole table is locked.
InnoDB on the other hand uses row-level locking, meaning, that row is the only row locked from the table during a transaction. InnoDB can be slower at searches because it doesn't offer full text search like MyISAM, but that isn't a big problem when you compare it to table-level locking of MyISAM. If you use InnoDB, like many large sites, then you could use a server side search engine like Sphinx for full text searches. Or you could even use a MyISAM table to do the searching like f00 suggested. I'd personally recommended InnoDB mainly because of the row-level locking feature, but also because you can implement full text searching in many other ways.
Basically, if you have a message board application with lots of selects, inserts as well as updates, InnoDB is probably the generally appropriate choice.
But if you're not building something like that (or any other thing with registered users) and your working mostly with static content (or more reads than writes), then you could use MyISAM.
Yes indeed you may use both in the same database, you may choose for each table separately.
In short, InnoDB is good if you are working on something that needs a reliable database that can handles a lot of INSERT and UPDATE instructions.
and, MyISAM is good if you needs a database that will mostly be taking a lot of read (SELECT) instructions rather than write (INSERT and UPDATES), considering its drawback on the table-lock thing.
you may want to check out;
Pros and Cons of InnoDB
Pros and Cons of MyISAM
You don't choose InnoDB or MyISAM on a database level, but instead on a table level. So within the one database you could have some tables running the InnoDB engine and some running MyISAM. As you pointed out, you could choose to use InnoDB on the tables that require transactions etc, and MyISAM where you need other features such as fulltext searching.
I heard this today during interview for java developer. I had to list some advantages of MyISAM over InnoDB and why it's still being widely used. And they were waiting to hear from me the answer as the title of this question.
As I understand from their own answer: MyISAM doesn't have foreign keys and DB can be easily clustered (one table per server for example). But why can't we simply create InnoDB tables without foreign keys? This explaination sounds strange to me..
There is no silver bullet answer here. You need to know the pros and cons of each before you make a decision on which one you use for any particular application.
InnoDB:
supports FK's
supports transactions
uses a large memory buffer for operation
supports row level locking
But has a much higher maintenance cost -- you really need to tune your memory usage, configure your table files, etc.
MyISAM:
has a bunch of special column features that InnoDB doesn't, like:
full text indexes
spatial columns (I'm pretty sure this doesn't work with InnoDB)
Very fast for primary read/append use cases (table locks for updates, deletes, but not for inserts)
Also typically has faster inserts
caches indexes in memory (key buffer), but relies on the OS to buffer the actual data pages
For example, I'd use InnoDB for things like ecommerce, user databases or anything that I want to use transactions in.
For data warehouses, logging, reporting, etc I'd probably use MyISAM.
I had to list some advantages of MyISAM over InnoDB
FULLTEXT search
...
no, that's it.
(OK, there are some cases where MyISAM is faster than InnoDB, but rarely enough that it's worth putting up with the lack of ACID-compliance. Today the main reason for doing anything with MyISAM is to get fulltext search which is sadly not supported in InnoDB.)
I am not sure if this is no longer true MyISAM is faster than InnoDB for reads.
Also, MyISAM tables are stored in separate files and (from what I can remember) you can actually transport those files to another MySQL database and is easier to backup.
By default InnoDB databases are stored in one huge glob on the file system.
As for why it is still being widely used, I always figured it was because it is the default option. Personally, I still believe that the advantages of InnoDB triumphs MyISAM and MyISAM also has problems with data integrity from my experience.
You certainly could create InnoDB tables without foreign keys, but that is cutting out one of the main advantages of it: referential integrity.
However, since MyISAM isn't built with the intent of referential integrity table keys can be stored differently, and perhaps more efficiently.
There are also some differences in locking and access. InnoDB supports row level locking, whereas MyISAM only supports table-level locking. Depending on the queries you're performing (SELECTS versus INSERTS/UPDATES) this can have a noticeable effect on performance.
You prolly need to read up on the Mysql Peformance blog.