PostgreSQL中int8、int64及string对应的数据库类型是什么？

Great question! It’s super common to run into type name mismatches when switching between databases/programming languages and PostgreSQL—let’s break down exactly how these types translate:

• int8: This isn’t a "missing" type at all—it’s actually an alias for PostgreSQL’s native BIGINT type. Both names refer to a signed 64-bit integer, so you can use int8 or BIGINT interchangeably in your table definitions.

• int64: If you’re talking about a standard 64-bit signed integer (not an auto-incrementing ID), this maps directly to BIGINT (or its int8 alias). The BIGSERIAL type you noticed is a specialized variant: it creates an auto-incrementing column backed by a sequence, so only use that when you need a column that generates unique, sequential values (like a primary key ID)—not for just any 64-bit integer field.

• string: PostgreSQL doesn’t have a literal string type, but you have two strong equivalents:

  • VARCHAR(n): Enforces a maximum length n for the string (e.g., VARCHAR(255) for a string up to 255 characters).
  • TEXT: Stores unlimited-length text with no explicit constraint.

  Fun fact: PostgreSQL treats VARCHAR(n) and TEXT almost identically under the hood—both can handle long strings, the only difference is the optional length check. Use VARCHAR(n) if you need to enforce a length limit, otherwise TEXT is a flexible, no-fuss choice.

Example Table Definition #

Here’s how you’d write a table using PostgreSQL’s native types to match the requested types:

CREATE TABLE candidate_demo (
    small_id int8 PRIMARY KEY, -- Matches int8
    large_value BIGINT, -- Matches int64 (standard integer)
    user_name VARCHAR(100), -- Matches string with 100-char limit
    notes TEXT -- Matches string with no limit
);

内容的提问来源于stack exchange，提问作者Артем