db(migration): merge slug partial unique into 002_posts.sql

migrations/002_posts.sql

@@ -17,12 +17,12 @@ CREATE TABLE posts (
     updated_at   TIMESTAMPTZ NOT NULL DEFAULT NOW(),
     deleted_at   TIMESTAMPTZ,
 
-    CONSTRAINT posts_slug_unique UNIQUE (slug),
     CONSTRAINT posts_status_check CHECK (status IN ('draft', 'published'))
 );
 
 CREATE INDEX idx_posts_status_published ON posts(status, published_at DESC) WHERE deleted_at IS NULL;
 CREATE INDEX idx_posts_slug ON posts(slug) WHERE deleted_at IS NULL;
+CREATE UNIQUE INDEX idx_posts_slug_unique ON posts(slug) WHERE deleted_at IS NULL;
 
 CREATE TABLE tags (
     id   SERIAL PRIMARY KEY,

migrations/003_slug_partial_unique.sql

@@ -1,5 +0,0 @@
--- 删除全局唯一约束
-ALTER TABLE posts DROP CONSTRAINT IF EXISTS posts_slug_unique;
-
--- 创建部分唯一索引（仅对未删除记录）
-CREATE UNIQUE INDEX idx_posts_slug_unique ON posts(slug) WHERE deleted_at IS NULL;