Description:
The documentation for UNIQUE indexes is inconsistent between CREATE TABLE and CREATE INDEX.
The CREATE TABLE section on UNIQUE indexes does not discuss prefixes and mentions something about _rowid.
The CREATE INDEX section on UNIQUE indexes discusses prefixes but does not mention anything about _rowid.
How to repeat:
Excerpt from CREATE TABLE Syntax
https://dev.mysql.com/doc/refman/5.7/en/create-table.html
UNIQUE
A UNIQUE index creates a constraint such that all values in the index must be distinct. An error occurs if you try to add a new row with a key value that matches an existing row. For all engines, a UNIQUE index permits multiple NULL values for columns that can contain NULL.
If a UNIQUE index consists of only one column that has an integer type, you can also refer to the column as _rowid in SELECT statements.
Excerpt from CREATE INDEX Syntax
https://dev.mysql.com/doc/refman/5.7/en/create-index.html
A UNIQUE index creates a constraint such that all values in the index must be distinct. An error occurs if you try to add a new row with a key value that matches an existing row. For all engines, a UNIQUE index permits multiple NULL values for columns that can contain NULL. If you specify a prefix value for a column in a UNIQUE index, the column values must be unique within the prefix.
Suggested fix:
Use the same text to describe unique indexes on both pages.
Add the _rowid reference to the CREATE INDEX page.
Does the existing _rowid reference on the CREATE TABLE page address the documentation requested in bug #42539?
