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https://dev.mysql.com/doc/refman/5.7/en/innodb-limits.html
A table can contain a maximum of 1017 columns (raised in MySQL 5.6.9 from the earlier limit of 1000). For example, you might hit this limit with a column prefix index of more than 255 characters on a TEXT or VARCHAR column, assuming a utf8mb3 ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-memcached-setup.html
Entries in the containers table provide a mapping to InnoDB table columns. Creating a New Table and Column Mapping This example shows how to setup your own InnoDB table with the daemon_memcached plugin. The table must have a key column with a unique ... This section describes how to set up the daemon_memcached plugin on a MySQL ...
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndbinfo-server-locks.html
The transaction ID shown in the transid column is the identifier generated by the NDB API for the transaction requesting or holding the current lock. The mode column shows the lock mode, which is always one of S (shared lock) or X (exclusive lock).
https://dev.mysql.com/doc/refman/5.7/en/optimize-character.html
For character and string columns, follow these guidelines: Use binary collation order for fast comparison and sort operations, when you do not need language-specific collation features. When comparing values from different columns, declare those ...
https://dev.mysql.com/doc/refman/5.7/en/optimizing-innodb-queries.html
Follow these guidelines for InnoDB indexes: Because each InnoDB table has a primary key (whether you request one or not), specify a set of primary key columns for each table, columns that are used in the most important and time-critical queries. Do ... To tune queries for InnoDB tables, create an appropriate set of indexes on each ...
https://dev.mysql.com/doc/refman/5.7/en/partitioning-pruning.html
When the optimizer can make use of partition pruning in performing this query, execution of the query can be an order of magnitude faster than the same query against a nonpartitioned table containing the same column definitions and data. The ...The ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-replication-tables.html
The following sections describe each replication table in more detail, including the correspondence between the columns produced by SHOW SLAVE STATUS and the replication table columns in which the same information appears. At this time, there are no ...This is similar to the information available from the SHOW SLAVE STATUS statement, but representation in table form is more accessible and has usability benefits: SHOW SLAVE STATUS output is useful for visual inspection, but not so much for programmatic ...
https://dev.mysql.com/doc/refman/5.7/en/problems-with-null.html
For example, the following statements are completely different: mysql> INSERT INTO my_table (phone) VALUES (NULL); mysql> INSERT INTO my_table (phone) VALUES (''); Both statements insert a value into the phone column, but the first inserts a NULL ...
https://dev.mysql.com/doc/refman/5.7/en/ansi-diff-foreign-keys.html
The MATCH clause in the SQL standard controls how NULL values in a composite (multiple-column) foreign key are handled when comparing to a primary key in the referenced table. (It is possible to implement other semantics using triggers.) MySQL ...
https://dev.mysql.com/doc/refman/5.7/en/binary-varbinary.html
For the latter types, the BINARY attribute does not cause the column to be treated as a binary string column. Instead, it causes the binary (_bin) collation for the column character set (or the table default character set if no column character set ... The BINARY and VARBINARY types are similar to CHAR and VARCHAR, except that they store binary strings rather than nonbinary ...