For Access Converts Only: Daemons and Services

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For Access Converts Only: Daemons and Services

MS SQL Server administrators will be familiar with the concept of a service, because MS SQL Server runs as a service under Windows (and so does the Windows version of MySQL). However, if you have used only Access, a bit of explanation will help you better understand MySQL. Use MS SQL Server as an example. In Access, you directly open the *.mdb file, which is where the data (among other things) is stored. Call that shared file mode, because multiple users can open and read data simultaneously from the same *.mdb file. Unlike in Access, when you use MS SQL Server, you don t directly access the file that holds the data. In MS SQL Server, the data files have the .mdf extension, but when you request the data that is in the file ”whether through an ODBC data source, a bound VB control, or whatever ”the SQL Server service handles the request, including any necessary security or login information. This service, which is a background process running under the operating system, is what actually looks into the file where the data is stored and retrieves the requested data. It then passes the data back to the requesting resource ”you (probably on another machine, although the client and server processes can both be on the same machine running at the same time).

In the Linux world, such services are called daemons, but they are the same thing, at least by the nature of their function. MySQL runs as a service, but not in shared-file mode like Access.

Safely Launching the mysql Daemon (mysqld) ”and Why You Should Care

The biggest reason to launch mysqld from the safe_mysqld script is that the script starts mysqld and then continuously verifies that mysqld is still running. If for any reason the daemon has died, safe_mysqld restarts it.

safe_mysqld understands the same options as mysqld.

Table 1.5 lists some of the more common or useful options for mysqld/safe_mysqld.

Table  1.5. Common Options for mysqld and safe_mysqld

Short Option	Long Option	Description
-b path	-- basedir =path	Indicates the path to the MySQL installation directory.
-h path	--datadir=path	Indicates the path to the MySQL data directory.
	--default-table-type=tbl_type	The default is MyISAM , but tbl_type can also be heap or isam .
	--init-file=file.sql	Specifies a file of SQL statements to be executed at startup.
-l path	--log[=path]	Initiates logging regarding queries and connections to clients .
	--log-isam[=file]	Index file logging for debugging ISAM or MyISAM operations.
	--log-update[=path]	The update log contains the text of any action query.
-Sg	--skip-grant-tables	When verifying user connections, skips the grant tables. This gives any client full access to everything. Reset to using the grant tables by sending mysqladmin flush-privileges.
	--skip-networking	Locks out all connections except local host.
	--skip-thread-priority	Action queries by default are given higher priority than select queries. This option sets all to equal priority.

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