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Getting ready in Software Display pdf417 2d barcode in Software Getting ready

Getting ready using software toembed pdf417 on asp.net web,windows application Jasper Reports For this recipe PDF-417 2d barcode for None , we will need a MySQL user who has SELECT access to all schemata in the MySQL installation. We assume the admin4mysql account is used throughout the following steps..

How to do it... 1. Connect to t Software pdf417 2d barcode he database using the admin4mysql account. 2.

Enter the following SQL statement:. SELECT DATA_FRE E/(1024*1024) AS FREE_MB, TABLE_SCHEMA, TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE ENGINE="InnoDB";. 3. Read the rem Software barcode pdf417 aining free tablespace (in MBytes) from the results:. 6 . How it works... The statement e ntered in step 2 simply reads the DATA_FREE column from the table INFORMATION_SCHEMA.TABLES and displays it in a convenient way (including a downscaling to show MBytes instead of bytes). For each table in each schema, the remaining free tablespace is shown (in MByte).

As you have noticed, most tables in the above example show the identical value of 134 MBytes. This is due to the fact that all these tables are stored in a shared MySQL tablespace (as defined by the innodb_data_home_dir variable). For most InnoDB installations, this will be the typical setup: all data is stored in a common tablespace, thus all tables will show the identical value for remaining tablespace.

In our example, however, the first table shows a different value. This is because this table was created in a table-specific tablespace, which can be achieved by using the innodb_file_ per_table parameter in the MySQL configuration. All tables that are created with this setting are created in separate files.

The files are extended in size as needed, but are not shrunk automatically if data is deleted from the table. The value retrieved by the above recipe shows the size available with the current file sizes (both for shared and file-per-table tablespace). If autoextending tablespaces are used, the remaining space on the file system has to be added to this value to calculate the true available space.

. Monitoring and Analyzing MySQL Installation Remaining autoextend space = Free tablespace + Remaining file system space Autoextending t barcode pdf417 for None ablespace is in place when the innodb_file_per_table setting is used or if the innodb_data_home_dir definition includes an autoextend suffix.. Note that for i nnodb_data_home_dir the default value ibdata1:10M:autoextend is used, which means automatic extension is in place!. In these cases, Software PDF417 the free tablespace value discussed above is not the only relevant value; you should additionally establish a monitoring for the available space on the disk device the tablespace files are stored on.. Please note tha t for both autoextend and innodb_file_per_table the tablespace will be extended as needed, but once the space is allocated for InnoDB use, it will not be released automatically if less storage is needed. With innodb_file_per_table, unused tablespace can be released by executing an OPTIMIZE TABLE command, resulting in smaller tablespace files..

There"s more... The above appro ach will only work for MySQL version 5.1.28 or higher, as these versions expose the remaining InnoDB tablespace in the DATA_FREE column of INFORMATION_SCHEMA.

TABLES. To retrieve the data from versions before that, you will have to take a look at the TABLE_COMMENT column:. Note that the values are given in KB, not in bytes as in the DATA_FREE column. 6 . An alternative pdf417 for None way to retrieve this information without explicitly accessing INFORMATION_ SCHEMA is to use the SHOW TABLE STATUS command, which shows the status (including the comment) for each table in the currently selected schema.. See also Defining an alternative user for administrative tasks Establishing alerting mechanisms for low remaining tablespace by using triggers In the previous PDF-417 2d barcode for None recipe, we introduced a way to read the remaining InnoDB tablespace. While it is important to have this information at hand, in a professional setting you will have to make sure that your database will not run out of tablespace. To avoid having to manually check the remaining tablespace on a regular basis (you have better things to do, especially on weekends and on vacation, right ), an automatic monitoring mechanism is needed.

It is not in the scope of this book to describe how to establish a working monitoring and alerting infrastructure. On most platforms you will have means to monitor for certain conditions and/or alert people or groups responsible for a particular issue. Typical examples for alerting solutions are third-party products like Nagios, Insight Manager, or OpenView, or even the good old e-mail.

Alerts can be triggered for example by trigger files, certain system log entries, SNMP, or specific clients. In this recipe, we will show you how to establish a monitoring mechanism for remaining InnoDB tablespace that can easily be adapted to use the alerting mechanism of your choice..

Note that this recipe is targeted at installations with a fixed InnoDB tablespace size. Scenarios that rely on the autoextend feature of InnoDB have to take the available file system space into account as well..

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