减去2 hstore，您可能需要添加显式类型强制转换 [英] Substract 2 hstore, You might need to add explicit type casts

问题描述

postgres的文档具有hstore-hstore，可从左操作数中删除匹配对。已安装的postgres扩展。

Documentation for postgres has hstore - hstore which delete matching pairs from left operand. Installed postgres extensions.

当我尝试

select public.hstore('"x"=>"30", "y"=>"c"') - 
       public.hstore('"x"=>"30","y"=>"fred"')

在以下

ERROR:  operator does not exist: public.hstore - public.hstore
LINE 3:  select public.hstore('"x"=>"30", "y"=>"c"') - public.hstore...
                                                     ^
HINT:  No operator matches the given name and argument type(s). You might need to add explicit type casts.

推荐答案

您已经安装了 hstore 扩展到 public 模式中，该模式不在您的 search_path 中。要找到类型，您需要对它们进行模式限定，但不限定适用于操作符的- 运算符

You've installed the hstore extension into the public schema, which is not on your search_path. To find the types you're schema-qualifying them but you're not qualifying the - operator that works on those types.

这意味着将找不到 hstore 的运算符定义。您必须：

This means that hstore's operator definitions will not be found. You must:

• 使用 OPERATOR（public .-）对模式进行限定;


• 将 public 放在 search_path 上；或


• 卸载 hstore ，然后将其安装到在<$ c上是的专用模式中$ c> search_path 。

• Schema-qualify the operator using OPERATOR(public.-);
• Put public on the search_path; or
• Uninstall hstore and then install it into its own dedicated schema that is on the search_path.

模式限定的运算符语法的示例为：

An example of schema-qualified operator syntax is:

SELECT 1 OPERATOR(pg_catalog.-) 2;

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