最适合我案例的解决方案如下：

The solution that works best for my case is the following:

我只是将json视为文本并在文本上创建索引。

I simply treat json as text and create an index on the text.

>> create index on foo ((json::text));

然后必须转换查询，以便它使用索引。

A query would then have to be transformed so that it uses the index.

解释显示是否使用了索引。

Explain reveals whether the index is used or not.

>> explain select * from foo where json::text = 'foo';