显然，我们不能。例如，我有一个简单的表：

CREATE TABLE test (
  id SERIAL PRIMARY KEY,
  loc double precision[]
);

我想从中查询文档，按距离排序，

SELECT loc FROM test ORDER BY loc <-> ARRAY[0, 0, 0, 0]::double precision[];

它不起作用：

Query Error: error: operator does not exist: double precision[] <-> double precision[]

文档中也没有提到数组的<->。我在这个问题的公认答案中找到了一个解决方法，但它有一些限制，特别是在数组长度上。尽管有一篇文章（用俄语写）建议在数组大小限制方面采取一种变通方法。创建示例表：

import postgresql
def setup_db():
    db = postgresql.open('pq://user:pass@localhost:5434/db')
    db.execute("create extension if not exists cube;")
    db.execute("drop table if exists vectors")
    db.execute("create table vectors (id serial, file varchar, vec_low cube, vec_high cube);")
    db.execute("create index vectors_vec_idx on vectors (vec_low, vec_high);")

元素插入：

query = "INSERT INTO vectors (file, vec_low, vec_high) VALUES ('{}', CUBE(array[{}]), CUBE(array[{}]))".format(
            file_name,
            ','.join(str(s) for s in encodings[0][0:64]),
            ','.join(str(s) for s in encodings[0][64:128]),
        )
db.execute(query)

元素查询：

import time
import postgresql
import random
db = postgresql.open('pq://user:pass@localhost:5434/db')
for i in range(100):
    t = time.time()
    encodings = [random.random() for i in range(128)]
    threshold = 0.6
    query = "SELECT file FROM vectors WHERE sqrt(power(CUBE(array[{}]) <-> vec_low, 2) + power(CUBE(array[{}]) <-> vec_high, 2)) <= {} ".format(
        ','.join(str(s) for s in encodings[0:64]),
        ','.join(str(s) for s in encodings[64:128]),
        threshold,
    ) + \
            "ORDER BY sqrt(power(CUBE(array[{}]) <-> vec_low, 2) + power(CUBE(array[{}]) <-> vec_high, 2)) ASC LIMIT 1".format(
                ','.join(str(s) for s in encodings[0:64]),
                ','.join(str(s) for s in encodings[64:128]),
            )
    print(db.query(query))
    print('inset time', time.time() - t, 'ind', i)