How to create a primary key using the hash method in postgresql
有没有办法使用哈希方法创建主键？ 以下两个陈述都不起作用：
1 2 3 | oid CHAR(30) PRIMARY KEY USING hash PRIMARY KEY(oid) USING hash |
我假设你打算使用哈希索引方法/类型。
主键是约束。一些约束可以创建索引以便正常工作(但不应该依赖这个事实)。 F.ex.
如果需要，您也可以设置哈希索引(除了
1 | CREATE INDEX name ON TABLE USING hash (COLUMN); |
但是，如果你愿意这样做，你应该知道哈希索引有一些限制(直到PostgreSQL 10)：
Hash index operations are not presently WAL-logged, so hash indexes might need to be rebuilt with REINDEX after a database crash if there were unwritten changes. Also, changes to hash indexes are not replicated over streaming or file-based replication after the initial base backup, so they give wrong answers to queries that subsequently use them. For these reasons, hash index use is presently discouraged.
也：
Currently, only the B-tree, GiST and GIN index methods support multicolumn indexes.
注意：遗憾的是，
注2：