MySql 中文参考指南

If the value should ever change, there is potentially a lot of index maintenance to re-sort the clustered index and update the copies of the primary key value that are repeated in each secondary index.

Even seemingly stable values can change in unpredictable ways that are difficult to represent correctly in the database. For example, one country can change into two or several, making the original country code obsolete. Or, rules about unique values might have exceptions. For example, even if taxpayer IDs are intended to be unique to a single person, a database might have to handle records that violate that rule, such as in cases of identity theft. Taxpayer IDs and other sensitive ID numbers also make poor primary keys, because they may need to be secured, encrypted, and otherwise treated differently than other columns.

An s-lock provides read access to a common resource.

An x-lock provides write access to a common resource while not permitting inconsistent reads by other threads.

An sx-lock provides write access to a common resource while permitting inconsistent reads by other threads. sx-locks were introduced in MySQL 5.7 to optimize concurrency and improve scalability for read-write workloads.

The shared InnoDB system tablespace, which is comprised of one or more ibdata files.

A file-per-table tablespace, comprised of an individual .ibd file.

A shared general tablespace, comprised of an individual .ibd file. General tablespaces were introduced in MySQL 5.7.6.

Section 2.9.2.1, “Troubleshooting Problems Starting the MySQL Server”

Section 8.2.22, “Troubleshooting Problems Connecting to MySQL”

Section B.3.3.2, “How to Reset the Root Password”

Section B.3.2, “Common Errors When Using MySQL Programs”

Section 17.20, “InnoDB Troubleshooting”.

Connector/NET: Connector/NET Versions

Connector/C++ 8.0: Platform Support and Prerequisites