Is there a limit to the number of indexes in MyISAM?
There is a limit of (2 32) 2 (1.844E+19) rows in a MyISAM table. The maximum number of indexes per MyISAM table is 64. The maximum number of columns per index is 16.
How is the MyISAM table stored on disk?
Each MyISAM table is stored on disk in two files. The files have names that begin with the table name and have an extension to indicate the file type. The data file has an .MYD ( MYData) extension. The index file has an .MYI ( MYIndex) extension.
When to insert a new row in MyISAM?
MyISAM supports concurrent inserts: If a table has no free blocks in the middle of the data file, you can INSERT new rows into it at the same time that other threads are reading from the table. A free block can occur as a result of deleting rows or an update of a dynamic length row with more data than its current contents.
What happens when a query runs against a MyISAM table?
When a query runs against a MyISAM table, the entire table in which it is querying will be locked. This means subsequent queries will only be executed after the current one is finished. If you are reading a large table, and/or there are frequent read and write operations, this can mean a huge backlog of queries.
How big of a file can be stored in MyISAM?
Large files (up to 63-bit file length) are supported on file systems and operating systems that support large files. There is a limit of (2 32) 2 (1.844E+19) rows in a MyISAM table. The maximum number of indexes per MyISAM table is 64.
MyISAM supports concurrent inserts: If a table has no free blocks in the middle of the data file, you can INSERT new rows into it at the same time that other threads are reading from the table. A free block can occur as a result of deleting rows or an update of a dynamic length row with more data than its current contents.
How to specify MyISAM in index file in MySQL?
The index file has an .MYI ( MYIndex) extension. To specify explicitly that you want a MyISAM table, indicate that with an ENGINE table option: In MySQL 5.6, it is normally necessary to use ENGINE to specify the MyISAM storage engine because InnoDB is the default engine.
When a query runs against a MyISAM table, the entire table in which it is querying will be locked. This means subsequent queries will only be executed after the current one is finished. If you are reading a large table, and/or there are frequent read and write operations, this can mean a huge backlog of queries.