* The big difference between MySQL Table Type MyISAM and InnoDB is that InnoDB supports transaction
* InnoDB supports some newer features: Transactions, row-level locking, foreign keys
* InnoDB is for high volume, high performance
Most people use MyISAM if they need speed and InnoDB for data integrity. You can use more than one or any combination of these table types in your database. Remember to asses the needs of your application before building it. Even though MyISAM is faster than InnoDB in the MySQL world, InnoDB is fast compared to any database engine.With InnoDB you get transactions, speed and integrity three features not usually used in the same sentence.
InnoDB has been designed for maximum performance when processing large data volumes. Its CPU efficiency is probably not matched by any other disk-based relational database engine.
Fully integrated with MySQL Server, the InnoDB storage engine maintains its own buffer pool for caching data and indexes in main memory. InnoDB stores its tables and indexes in a tablespace, which may consist of several files (or raw disk partitions). This is different from, for example, MyISAM tables where each table is stored using separate files. InnoDB tables can be of any size even on operating systems where file size is limited to 2GB.
Tuesday, February 8, 2011
Thursday, February 3, 2011
Some examples of using UNIX find command.
The find command allows the Unix user to process a set of files and/or directories in a file subtree.
You can specify the following:
* where to search (pathname)
* what type of file to search for (-type: directories, data files, links)
* how to process the files (-exec: run a process against a selected file)
* the name of the file(s) (-name)
* perform logical operations on selections (-o and -a)
Search for file with a specific name in a set of files (-name)
find . -name "rc.conf" -print
This command will search in the current directory and all sub directories for a file named rc.conf.
Note: The -print option will print out the path of any file that is found with that name. In general -print wil print out the path of any file that meets the find criteria.
How to apply a unix command to a set of file (-exec).
find . -name "rc.conf" -exec chmod o+r '{}' \;
This command will search in the current directory and all sub directories. All files named rc.conf will be processed by the chmod -o+r command. The argument '{}' inserts each found file into the chmod command line. The \; argument indicates the exec command line has ended.
The end results of this command is all rc.conf files have the other permissions set to read access (if the operator is the owner of the file).
How to apply a complex selection of files (-o and -a).
find /usr/src -not \( -name "*,v" -o -name ".*,v" \) '{}' \; -print
This command will search in the /usr/src directory and all sub directories. All files that are of the form '*,v' and '.*,v' are excluded. Important arguments to note are:
* -not means the negation of the expression that follows
* \( means the start of a complex expression.
* \) means the end of a complex expression.
* -o means a logical or of a complex expression.
In this case the complex expression is all files like '*,v' or '.*,v'
The above example is shows how to select all file that are not part of the RCS system. This is important when you want go through a source tree and modify all the source files... but ... you don't want to affect the RCS version control files.
How to search for a string in a selection of files (-exec grep ...).
find . -exec grep "www.athabasca" '{}' \; -print
This command will search in the current directory and all sub directories. All files that contain the string will have their path printed to standard output.
If you want to just find each file then pass it on for processing use the -q grep option. This finds the first occurrance of the search string. It then signals success to find and find continues searching for more files.
find . -exec grep -q "www.athabasca" '{}' \; -print
This command is very important for process a series of files that contain a specific string. You can then process each file appropriately. An example is find all html files with the string "www.athabascau.ca". You can then process the files with a sed script to change those occurrances of "www.athabascau.ca" with "intra.athabascau.ca".
You can specify the following:
* where to search (pathname)
* what type of file to search for (-type: directories, data files, links)
* how to process the files (-exec: run a process against a selected file)
* the name of the file(s) (-name)
* perform logical operations on selections (-o and -a)
Search for file with a specific name in a set of files (-name)
find . -name "rc.conf" -print
This command will search in the current directory and all sub directories for a file named rc.conf.
Note: The -print option will print out the path of any file that is found with that name. In general -print wil print out the path of any file that meets the find criteria.
How to apply a unix command to a set of file (-exec).
find . -name "rc.conf" -exec chmod o+r '{}' \;
This command will search in the current directory and all sub directories. All files named rc.conf will be processed by the chmod -o+r command. The argument '{}' inserts each found file into the chmod command line. The \; argument indicates the exec command line has ended.
The end results of this command is all rc.conf files have the other permissions set to read access (if the operator is the owner of the file).
How to apply a complex selection of files (-o and -a).
find /usr/src -not \( -name "*,v" -o -name ".*,v" \) '{}' \; -print
This command will search in the /usr/src directory and all sub directories. All files that are of the form '*,v' and '.*,v' are excluded. Important arguments to note are:
* -not means the negation of the expression that follows
* \( means the start of a complex expression.
* \) means the end of a complex expression.
* -o means a logical or of a complex expression.
In this case the complex expression is all files like '*,v' or '.*,v'
The above example is shows how to select all file that are not part of the RCS system. This is important when you want go through a source tree and modify all the source files... but ... you don't want to affect the RCS version control files.
How to search for a string in a selection of files (-exec grep ...).
find . -exec grep "www.athabasca" '{}' \; -print
This command will search in the current directory and all sub directories. All files that contain the string will have their path printed to standard output.
If you want to just find each file then pass it on for processing use the -q grep option. This finds the first occurrance of the search string. It then signals success to find and find continues searching for more files.
find . -exec grep -q "www.athabasca" '{}' \; -print
This command is very important for process a series of files that contain a specific string. You can then process each file appropriately. An example is find all html files with the string "www.athabascau.ca". You can then process the files with a sed script to change those occurrances of "www.athabascau.ca" with "intra.athabascau.ca".
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