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InnoDB
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the difference in composition:
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Each myisam is stored as three files on disk. The first file name begins with the name of the table, and the extension indicates the file type.
The. frm file stores the table definition.
The data file has an extension of. MYD (MYData).
The extension of the index file is. MYI (Myindex).
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A disk-based resource is a InnoDB tablespace data file and its log file, and the size of the InnoDB table is limited only by the size of the operating system file, typically 2GB
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transaction Processing Aspects :
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Tables of the MyISAM type emphasize performance, which is performed more quickly than the InnoDB type, but does not provide transactional support
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InnoDB provides transaction support transactions, external keys and other advanced database functions
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select update,insert , Delete Action |
if performing a large number of select,myisam is a better choice for |
1. If your data performs a large number of INSERT or UPDATE , you should use the InnoDB table for performance reasons 2.delete from Table , InnoDB does not reestablish the table, but deletes one row at a time. the 3.load table from MASTER operation has no effect on InnoDB, and the workaround is to first change the InnoDB table to a MyISAM table , the data is imported and then changed to the InnoDB table, but the table for the extra InnoDB attributes (such as foreign keys) used is not |
to auto_increment |
the internal processing of one auto_incremen column per table. MyISAM for INSERT and The update operation automatically updates this column . This makes the Auto_increment column faster (at least 10%). The value at the top of the sequence cannot be exploited after it has been deleted. (When the Auto_increment column is defined as the last column of a multicolumn index, the use of values removed from the top of the sequence can occur). The auto_increment value can be used by ALTER TABLE or MYISAMCH to reset for fields of type auto_increment, The InnoDB must contain only the index of the field, but in the MyISAM table, you can establish a federated index with other fields better and faster auto_increment processing |
If you specify a auto_increment column for a table, the InnoDB table handle in the data dictionary contains a counter called the autogrow counter, which is used to assign a new value to the column. The autogrow counters are stored only in main memory, not on disk algorithmic implementations of the calculator, see Auto_increment column in InnoDB How to work |
the exact number of rows in the table
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Select COUNT (*) from Table,myisam as long as you simply read the number of rows saved, note that when the COUNT (*) statement contains a where condition, the operation of the two tables is the same
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The exact number of rows in a table is not saved in InnoDB, that is, when you execute select COUNT (*) from table, InnoDB scans the entire table to calculate how many rows
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Lock
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Table lock
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Provides row lock (locking on row level), providing no lock read consistent with Oracle type (non-locking read in Selects), in addition, the row lock of the InnoDB table is not absolute, and if MySQL cannot determine the range to scan when executing an SQL statement, the InnoDB table also locks the full table, such as the Update table set num=1 where name like "% aaa% " |