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26.1 Prerequisites for Using the sys Schema

https://dev.mysql.com/doc/refman/5.7/en/sys-schema-prerequisites.html

Before using the sys schema, the prerequisites described in this section must be satisfied. Because the sys schema provides an alternative means of accessing the Performance Schema, the Performance Schema must be enabled for the sys schema to work.

26.3 sys Schema Progress Reporting

https://dev.mysql.com/doc/refman/5.7/en/sys-schema-progress-reporting.html

The following sys schema views provide progress reporting for long-running transactions: processlist session x$processlist x$session Assuming that the required instruments and consumers are enabled, the progress column of these views shows the ...

26.4.2.1 The sys_config Table

https://dev.mysql.com/doc/refman/5.7/en/sys-sys-config.html

To enable debug output without having to set that variable in individual sessions, add the option to the table: mysql> INSERT INTO sys.sys_config (variable, value) VALUES('debug', 'ON'); To change the debug setting in the table, do two things. This ...

11.2.3 The TIME Type

https://dev.mysql.com/doc/refman/5.7/en/time.html

In particular, any fractional part in a value inserted into a TIME column is stored rather than discarded. MySQL retrieves and displays TIME values in 'hh:mm:ss' format (or 'hhh:mm:ss' format for large hours values). The hours part may be so large ...

11.2.10 2-Digit Years in Dates

https://dev.mysql.com/doc/refman/5.7/en/two-digit-years.html

For YEAR, the rules are the same, with this exception: A numeric 00 inserted into YEAR results in 0000 rather than 2000. Date values with 2-digit years are ambiguous because the century is unknown. Such values must be interpreted into 4-digit form ...

12.3 Type Conversion in Expression Evaluation

https://dev.mysql.com/doc/refman/5.7/en/type-conversion.html

When an operator is used with operands of different types, type conversion occurs to make the operands compatible. For example, MySQL automatically converts strings to numbers as necessary, and vice versa. mysql> SELECT 1+'1'; -> 2 mysql> SELECT ...

13.2.11 UPDATE Statement

https://dev.mysql.com/doc/refman/5.7/en/update.html

Note Unlike the case when using PARTITION with an INSERT or REPLACE statement, an otherwise valid UPDATE ... UPDATE is a DML statement that modifies rows in a table. Single-table syntax: UPDATE [LOW_PRIORITY] [IGNORE] table_reference SET ...

8.8.1 Optimizing Queries with EXPLAIN

https://dev.mysql.com/doc/refman/5.7/en/using-explain.html

The EXPLAIN statement provides information about how MySQL executes statements: EXPLAIN works with SELECT, DELETE, INSERT, REPLACE, and UPDATE statements. When EXPLAIN is used with an explainable statement, MySQL displays information from the ...

7.4 Using mysqldump for Backups

https://dev.mysql.com/doc/refman/5.7/en/using-mysqldump.html

This output consists of CREATE statements to create dumped objects (databases, tables, stored routines, and so forth), and INSERT statements to load data into tables. This section describes how to use mysqldump to produce dump files, and how to ...

23.9 Restrictions on Views

https://dev.mysql.com/doc/refman/5.7/en/view-restrictions.html

The maximum number of tables that can be referenced in the definition of a view is 61. View processing is not optimized: It is not possible to create an index on a view. Indexes can be used for views processed using the merge algorithm. However, a ...

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