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https://dev.mysql.com/doc/refman/5.7/en/is-null-optimization.html
This optimization can handle one IS NULL for any key part. In the following query, MySQL uses key lookups only on the expression (t1.a=t2.a AND t2.a IS NULL) and is not able to use the key part on b: SELECT * FROM t1, t2 WHERE (t1.a=t2.a AND t2.a IS ... MySQL can perform the same optimization on col_name IS NULL that it can use for col_name = ...
https://dev.mysql.com/doc/refman/5.7/en/keyring-plugin-installation.html
Keyring service consumers require that a keyring plugin be installed. This section describes how to install the keyring plugin of your choosing. If you intend to use keyring functions in conjunction with the chosen keyring plugin, install the ...
https://dev.mysql.com/doc/refman/5.7/en/linux-installation-yum-repo.html
The installation command adds the MySQL Yum repository to your system's repository list and downloads the GnuPG key to check the integrity of the software packages. See Section 2.1.4.2, “Signature Checking Using GnuPG” for details on GnuPG key ...Before You Start As a popular, open-source software, MySQL, in its original or re-packaged form, is widely installed on many systems from various sources, including different software download sites, software repositories, and so ...
https://dev.mysql.com/doc/refman/5.7/en/load-xml.html
Suppose that we have a table named person, created as shown here: USE test; CREATE TABLE person ( person_id INT NOT NULL PRIMARY KEY, fname VARCHAR(40) NULL, lname VARCHAR(40) NULL, created TIMESTAMP ); Suppose further that this table is initially ...The tagname in the optional ROWS IDENTIFIED BY clause must also be given as a literal string, and must be surrounded by angle brackets (< and ...
https://dev.mysql.com/doc/refman/5.7/en/mrr-optimization.html
With the Disk-Sweep Multi-Range Read (MRR) optimization, MySQL tries to reduce the number of random disk access for range scans by first scanning the index only and collecting the keys for the relevant rows. Then the keys are sorted and finally the ... Reading rows using a range scan on a secondary index can result in many random disk accesses to the base table when the table is large and not stored in the storage engine's ...
https://dev.mysql.com/doc/refman/5.7/en/myisamchk-memory.html
For example, if you have more than 512MB RAM available, you could use options such as these (in addition to any other options you might specify): myisamchk --myisam_sort_buffer_size=256M \ --key_buffer_size=512M \ --read_buffer_size=64M \ ...
https://dev.mysql.com/doc/refman/5.7/en/myisamchk.html
The myisamchk utility gets information about your database tables or checks, repairs, or optimizes them. myisamchk works with MyISAM tables (tables that have .MYD and .MYI files for storing data and indexes). You can also use the CHECK TABLE and ...
https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-programs-ndb-import.html
--ai-increment=# Command-Line Format --ai-increment=# Introduced 5.7.18-ndb-7.6.2 Type Integer Default Value 1 Minimum Value 1 Maximum Value 4294967295 For a table with a hidden primary key, specify the autoincrement increment, like the ...
https://dev.mysql.com/doc/refman/5.7/en/mysql-indexes.html
Most MySQL indexes (PRIMARY KEY, UNIQUE, INDEX, and FULLTEXT) are stored in B-trees. To find the MIN() or MAX() value for a specific indexed column key_col. This is optimized by a preprocessor that checks whether you are using WHERE key_part_N = ...
https://dev.mysql.com/doc/refman/5.7/en/partitioning-handling-nulls.html
NULL is handled somewhat differently for tables partitioned by HASH or KEY. For tables that are partitioned by HASH or KEY, this result is treated for determining the correct partition as 0. Partitioning in MySQL does nothing to disallow NULL as ...