postgresql

Compare original and translation side by side

🇺🇸

Original

English

🇨🇳

Translation

Chinese

PostgreSQL

When to use

适用场景

Designing or changing multi-tenant tables with Row-Level Security (RLS)
Debugging tenant isolation issues
Adding/changing Alembic migrations for schema, RLS policies, or indexes
Writing tests that validate RLS isolation
Configuring PostgreSQL authentication, replication, or tuning

设计或修改带有行级安全（RLS）的多租户表
调试租户隔离问题
为schema、RLS策略或索引添加/修改Alembic迁移
编写验证RLS隔离性的测试
配置PostgreSQL认证、复制或调优

RLS Multi-tenancy Pattern

RLS多租户模式

Non-negotiables

必须遵循的规则

RLS context is mandatory for any tenant-scoped query
Context must be set inside the same transaction as the queries
No fallbacks for tenant ID (fail fast if missing)
Async-only DB access when using async frameworks

必须设置RLS上下文：所有租户范围的查询都需要设置
上下文必须与查询在同一事务内设置
租户ID无fallback方案：如果缺失则直接失败
异步框架下仅使用异步数据库访问

Setting RLS Context

设置RLS上下文

RLS works only if the current transaction has the context set:

sql

SET LOCAL app.current_tenant_id = '<tenant_uuid>';

Must run before the first tenant-scoped query in that transaction.

RLS仅在当前事务已设置上下文时生效：

sql

SET LOCAL app.current_tenant_id = '<tenant_uuid>';

必须在该事务中的第一个租户范围查询之前执行此操作。

Common Failure Modes

常见失败场景

Setting
```
SET LOCAL ...
```
after the first
```
select()
```
Setting the context in one session, then querying in another
Running queries outside the expected transaction scope

在第一个
```
select()
```
之后设置
```
SET LOCAL ...
```
在一个会话中设置上下文，却在另一个会话中查询
在预期的事务范围外执行查询

Typical RLS Policy

典型RLS策略

sql

ALTER TABLE some_table ENABLE ROW LEVEL SECURITY;

CREATE POLICY some_table_tenant_isolation
ON some_table
USING (tenant_id = current_setting('app.current_tenant_id', true)::uuid);

sql

ALTER TABLE some_table ENABLE ROW LEVEL SECURITY;

CREATE POLICY some_table_tenant_isolation
ON some_table
USING (tenant_id = current_setting('app.current_tenant_id', true)::uuid);

Multi-tenant Table Checklist

多租户表检查清单

Tenant ID column is UUID
FK to tenants table with
```
ON DELETE CASCADE
```
Indexes aligned with access patterns (usually tenant_id first)
- PostgreSQL does not auto-index FK columns — add explicit indexes
- UNIQUE allows multiple NULLs unless using
```
NULLS NOT DISTINCT
```
  (PG15+)
RLS is enabled and policies exist
Application code sets RLS context at transaction start

租户ID列类型为UUID
与租户表建立外键关联，并设置
```
ON DELETE CASCADE
```
索引与访问模式匹配（通常以tenant_id作为首列）
- PostgreSQL不会自动为外键列创建索引——需手动添加显式索引
- 除非使用
```
NULLS NOT DISTINCT
```
  （PG15+版本），否则UNIQUE约束允许多个NULL值
已启用RLS并配置相应策略
应用代码在事务开始时设置RLS上下文

Alembic Migrations Checklist

Alembic迁移检查清单

Add/modify schema (columns, constraints, FKs)
Create/update indexes
Enable RLS and create/adjust policies
Add verification (tests) for isolation
Provide a real downgrade (no stubs)

添加/修改schema（列、约束、外键）
创建/更新索引
启用RLS并创建/调整策略
添加隔离性验证（测试）
提供真实的回滚方案（不允许使用占位符）

RLS Isolation Testing Recipe

RLS隔离性测试方案

—

测试目标

Goal:

Data for tenant A is visible to tenant A
Data for tenant A is NOT visible to tenant B

Canonical flow:

Setup data through an admin session (RLS bypass) for tenant A and B
Assert via an RLS session:
- set context to tenant A → sees only tenant A data
- set context to tenant B → does not see tenant A data

租户A的数据仅对租户A可见
租户A的数据对租户B不可见

Destructive Operations Safety

标准流程

Hard rules:

Never run
```
DELETE
```
without a narrow
```
WHERE
```
targeting specific data
Never run
```
TRUNCATE
```
/
```
DROP
```
without explicit confirmation

Pre-flight before destructive actions:

Confirm exact target (tables / IDs / date range)
Run a
```
SELECT
```
/row count first and show results
Ask for final confirmation, then execute

通过管理员会话（绕过RLS）为租户A和B准备测试数据
通过RLS会话验证：
- 设置上下文为租户A → 仅能看到租户A的数据
- 设置上下文为租户B → 无法看到租户A的数据

References

破坏性操作安全规范

Schema & Design

硬性规则

table-design.md — Data types, constraints, indexing, partitioning, JSONB, safe schema evolution
charset-encoding.md — Character sets, encoding, collation, ICU, locale settings

禁止在没有精准
```
WHERE
```
条件定位特定数据的情况下执行
```
DELETE
```
禁止在没有显式确认的情况下执行
```
TRUNCATE
```
/
```
DROP
```

Authentication

破坏性操作前的预检步骤

authentication.md — pg_hba.conf, SCRAM-SHA-256, md5, peer, cert, LDAP, GSSAPI
authentication-oauth.md — OAuth 2.0 (PostgreSQL 18+), SASL OAUTHBEARER, validators
user-management.md — CREATE/ALTER/DROP ROLE, membership, GRANT/REVOKE, predefined roles

确认精准的操作目标（表/ID/日期范围）
先执行
```
SELECT
```
/行计数并查看结果
请求最终确认后再执行操作

Runtime Configuration

参考资料

—

Schema与设计

connection-settings.md — listen_addresses, max_connections, SSL, TCP keepalives
query-tuning.md — Planner settings, work_mem, parallel query, cost constants
replication.md — Streaming replication, WAL, synchronous commit, logical replication
vacuum.md — Autovacuum, vacuum cost model, freeze ages, per-table tuning
error-handling.md — exit_on_error, restart_after_crash, data_sync_retry

table-design.md — 数据类型、约束、索引、分区、JSONB、安全的schema演进
charset-encoding.md — 字符集、编码、排序规则、ICU、区域设置

Internals

认证

internals.md — Query processing pipeline, parser/rewriter/planner/executor, system catalogs, wire protocol, access methods
protocol.md — Wire protocol v3.2: message format, startup, auth, query, COPY, replication

authentication.md — pg_hba.conf、SCRAM-SHA-256、md5、peer、cert、LDAP、GSSAPI
authentication-oauth.md — OAuth 2.0（PostgreSQL 18+）、SASL OAUTHBEARER、验证器
user-management.md — CREATE/ALTER/DROP ROLE、角色成员、GRANT/REVOKE、预定义角色

postgresql

Original

Translation

PostgreSQL

PostgreSQL

When to use

适用场景

RLS Multi-tenancy Pattern

RLS多租户模式

Non-negotiables

必须遵循的规则

Setting RLS Context

设置RLS上下文

Common Failure Modes

常见失败场景

Typical RLS Policy

典型RLS策略

Multi-tenant Table Checklist

多租户表检查清单

Alembic Migrations Checklist

Alembic迁移检查清单

RLS Isolation Testing Recipe

RLS隔离性测试方案

测试目标

Destructive Operations Safety

标准流程

References

破坏性操作安全规范

Schema & Design

硬性规则

Authentication

破坏性操作前的预检步骤

Runtime Configuration

参考资料

Schema与设计

Internals

认证

See also

运行时配置

内部实现

相关链接