The PartialIndex (es) of MySQLInnoDB and PostgreSQL is different.

The PartialIndex of MySQLInnoDB is: bytes, typicallythefirstNcharacters (theprefix) ofalongVARCHARvalue. The PartialIndexes of PostgreSQL is: Apartialindexisanindexbuiltove

The Partial Index of MySQL InnoDB is: An index that represents only part of a column value, typically the first N characters (the prefix) of a long VARCHAR value. in PostgreSQL, Partial Indexes is: A partial index is an index built ove

MySQL InnoDB refers to the following Partial Index:

An index that represents only part of a column value, typically the first N characters (the prefix) of a long VARCHAR value.

PostgreSQL refers to the following Partial Indexes:

A partial index is an index built over a subset of a table; the subset is defined by a conditional expression (called the predicate of the partial index ). the index contains entries only for those table rows that satisfy the predicate. partial indexes are a specialized feature, but there are several situations in which they are useful.

Finally, PostgreSQL can do what MySQL InnoDB's Partial Index wants, and more.

The Partial Index of MySQL InnoDB is set to the prefix index (n bytes before the string). The possible cause isCHAR(32)Only the first 16 bytes indexes are supported.

PostgreSQL's Partial Indexes has benefited from many aspects and is even larger. Because Indexes on Expressions exists, you can also index suffix, or even the value obtained by the index through the string function, in addition to the prefix index of MySQL.

For example, PostgreSQL can set "I only need to index the username of the person born in January 1 」:

CREATE INDEX test_index ON test_table (username) WHERE birth_month = 1 AND birth_day = 1;

In MySQL, the problem that indexes need to be adjusted anyway, or another table needs to be split and then indexed can be reduced by making full use of these features of PostgreSQL...

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