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The comp_err creates the errmsg.sys file which is used by mysqld to determine the error messages that need to be displayed for different error codes. After the current update to MySQL, the error information comes from the messages_to_error_log.txt and messages_to_clients.txt files in the share directory.Before MySQL 8.0.19, the error information used to come from the errmsg-utf8.txt file in the sql/share directory. The comp_err also generates the mysqld_error.h, mysqld_ername.h, and mysqld_errmsg.h header files.The comp_err can be invoked in the following way −shell> comp_err [options]It supports the below options −--charset=dir_name, -C dir_nameIt is the character set directory. The default is ../sql/share/charsets.--debug=debug_options, -# ... Read More
The mysqld_multi command has been designed to manage several mysqld processes which listen for connections on different Unix socket files and TCP/IP ports. It can be used to start or stop servers, or report their current status.It can be invoked using the below code −shell> mysqld_multi [options] {start|stop|reload|report} [GNR[, GNR] ...]The start, stop, reload (stop and restart), and report indicate which operation needs to be performed. The designated operation can be performed for a single server or multiple servers, and this depends on the GNR list that follows the option name. GNR is the group number.Let us take an example ... Read More
The mysql.server will change the location to the MySQL installation directory. It will then invoke the mysqld_safe. To run the server as a specific user, an appropriate user option can be added to the [mysqld] group of the global /etc/my.cnf option file.It changes location to the MySQL installation directory, and later invokes mysqld_safe.To run the server as a specific user, an appropriate user option can be added to the [mysqld] group of the global /etc/my.cnf option file.It may be required to edit the mysql.server if it was installed as a binary distribution of MySQL in a nonstandard location.It has to ... Read More
What is mysqld_safeThe mysqld_safe command is considered as the right way to start a mysqld server on Unix.It adds certain safety features like restarting the server when an error occurs and logging runtime information to an error log.It tries to start an executable named mysqld. To override this default behavior and specify the name of the server explicitly, which is the one that the user wants to run, a --mysqld or -- mysqld-version option can be specified to mysqld_safe. The --ledir can also be used to tell the directory where mysqld_safe should look for the server.Options unknown to mysqld_safe are ... Read More
Let us understand about ‘mysqld’, the MySQL server −mysqldThe mysqld is also known as MySQL Server. It is a single multithreaded program that does most of the work in a MySQL installation. It doesn’t spawn additional processes.MySQL Server helps manage the access to the MySQL data directory which contains databases and tables. The data directory is the default location for other information like log files and status files.Note − Certain installation packages may contain a debugging version of the server by the name mysqld-debug.This version can be invoked instead of the mysqld for debugging support, memory allocation checking, as well ... Read More
There are 4 MySQL server and server-start up programs. They have been listed below −mysqldmysqld_safemysql.servermysqld_multimysqldis also known as MySQL Server. It is a single multithreaded program that does most of the work in a MySQL installation. It doesn’t spawn additional processes. MySQL Server helps manage the access to the MySQL data directory which contains databases and tables. The data directory is the default location for other information like log files and status files.When MySQL server starts, it listens to the network connections from client programs and helps manage the access to databases on behalf of these clients.To see options specified ... Read More
Let us understand how to get the MySQL path in the command prompt −To invoke MySQL programs easily, the path name of the MySQL bin directory can be added to the Windows system PATH environment variable.This can be done using the below mentioned steps −Before trying to add MySQL to Windows path, ensure that MySQL has been installed properly.Add MySQL to PathBelow are the steps to add MySQL to path −Step1 − Locate the mysql.exe file. We found in the following location −C:\Program Files\MySQL\MySQL Server 8.0\binStep 2 − Press Start and type “Environment Variables”. Click −Step 3 − Under ‘Advanced’, ... Read More
Environment variables can be set at the command prompt. This is done to affect the current invocation of the command processor, or to permanently set to affect the future invocations. To set a variable permanently, it can be set in a startup file or with the help of the interface provided by the system for the same purpose. The documentation of the command interpreter needs to be consulted for specific details.To specify a value for an environment variable, the syntax relevant for the command processor needs to be used.The command to set environment variables can be executed at the command ... Read More
Let us understand how to set environment variables on Linux for MySQL −Environment variables can be set at the command prompt. This is done to affect the current invocation of the command processor, or to permanently set to affect the future invocations.To set a variable permanently, it can be set in a startup file or with the help of the interface provided by the system for the same purpose. The documentation of the command interpreter needs to be consulted for specific details. To specify a value for an environment variable, the syntax relevant for the command processor needs to be ... Read More
Before a compressed table is created, ensure that the innodb_file_per_table configuration option is enabled, and innodb_file_format is set to Barracuda. These parameters can be found in the MySQL configuration file my.cnf or my.ini, or with the SET statement without having to shut down the MySQL server.To enable compression for a table, the clauses ROW_FORMAT=COMPRESSED, KEY_BLOCK_SIZE, or both can be used in a CREATE TABLE or ALTER TABLE statement.Let us see the statements to create a compressed table −QuerySET GLOBAL innodb_file_per_table=1; SET GLOBAL innodb_file_format=Barracuda; CREATE TABLE t1 (c1 INT PRIMARY KEY) ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=8;Here, If ROW_FORMAT=COMPRESSED is specified, the KEY_BLOCK_SIZE can be ... Read More