https://www.postgresql.org/docs/current/indexes-types.html

11.2 Index Types

11.2.3 GiST

GIST索引不是一种单一的索引，而是一种基础设施，在其中可以实现许多不同的索引策略。因此，可以使用GIST索引的特定运算符因索引策略(运算符类)而异。例如，PostgreSQL的标准分发版包括几种二维几何数据类型的GIST运算符类，这些数据类型支持使用这些运算符的索引查询：

<<   &<   &>   >>   <<|   &<|   |&>   |>>   @>   <@   ~=   &&

(See Section 9.11 for the meaning of these operators.) The GiST operator classes included in the standard distribution are documented in Table 68.1. Many other GiST operator classes are available in the contrib collection or as separate projects. For more information see Chapter 68

GiST indexes are also capable of optimizing “nearest-neighbor” searches, such as

SELECT * FROM places ORDER BY location <-> point '(101,456)' LIMIT 10;

which finds the ten places closest to a given target point. The ability to do this is again dependent on the particular operator class being used. In Table 68.1, operators that can be used in this way are listed in the column “Ordering Operators”.