71 lines
3.3 KiB
SQL
71 lines
3.3 KiB
SQL
-- 006_accommodation_history_constraint.sql
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-- 目标：移除 train_accommodation 全局唯一约束 uq_accommodation_enroll，
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-- 创建部分唯一索引 uq_accommodation_enroll_active (每个 enrollment 最多 1 条有效住宿)，
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-- 允许学员拥有多条退宿历史记录 (status=2)，彻底支持调房与历史留痕。
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DO $$
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DECLARE
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v_dup_count INTEGER;
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v_con_def TEXT;
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v_idx_def TEXT;
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BEGIN
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-- 1. Pre-Migration Data Safety Guard
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-- 检查是否已存在同一个 enrollment_id 拥有 2 条或以上处于有效状态 (0=预分配, 1=已入住) 的住宿记录
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SELECT COUNT(*) INTO v_dup_count
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FROM (
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SELECT enrollment_id
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FROM train_accommodation
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WHERE accommodation_status IN (0, 1)
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GROUP BY enrollment_id
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HAVING COUNT(*) > 1
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) t;
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IF v_dup_count > 0 THEN
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RAISE EXCEPTION 'Pre-migration check failed: found % enrollment(s) with multiple active accommodations (status IN (0,1)). Manual resolution required before applying migration 006.', v_dup_count;
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END IF;
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-- 2. Existing Constraint Guard (Idempotent Drop)
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-- 检查约束 uq_accommodation_enroll 是否存在且符合预期
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SELECT pg_get_constraintdef(c.oid) INTO v_con_def
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FROM pg_constraint c
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JOIN pg_class t ON c.conrelid = t.oid
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WHERE t.relname = 'train_accommodation'
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AND c.conname = 'uq_accommodation_enroll';
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IF v_con_def IS NOT NULL THEN
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-- 验证旧约束是否为 UNIQUE (enrollment_id)
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IF v_con_def ILIKE 'UNIQUE (enrollment_id)%' THEN
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RAISE NOTICE 'Dropping legacy global unique constraint: uq_accommodation_enroll';
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ALTER TABLE train_accommodation DROP CONSTRAINT uq_accommodation_enroll;
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ELSE
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RAISE EXCEPTION 'Constraint collision: constraint uq_accommodation_enroll exists but definition is unexpected: %', v_con_def;
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END IF;
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ELSE
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RAISE NOTICE 'Constraint uq_accommodation_enroll does not exist, skipping drop.';
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END IF;
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-- 3. New Index Collision Guard & Creation
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-- 检查部分唯一索引 uq_accommodation_enroll_active
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SELECT pg_get_indexdef(i.indexrelid) INTO v_idx_def
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FROM pg_index i
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JOIN pg_class c ON i.indexrelid = c.oid
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JOIN pg_class t ON i.indrelid = t.oid
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WHERE t.relname = 'train_accommodation'
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AND c.relname = 'uq_accommodation_enroll_active';
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IF v_idx_def IS NOT NULL THEN
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-- 验证已有索引是否为预期的部分唯一索引
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IF v_idx_def ILIKE '%UNIQUE INDEX uq_accommodation_enroll_active ON %train_accommodation% (enrollment_id)%WHERE (accommodation_status = ANY (ARRAY[0, 1]))%'
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OR v_idx_def ILIKE '%UNIQUE INDEX uq_accommodation_enroll_active ON %train_accommodation% (enrollment_id)%WHERE%accommodation_status IN (0, 1)%' THEN
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RAISE NOTICE 'Partial unique index uq_accommodation_enroll_active already exists with expected definition, skipping creation.';
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ELSE
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RAISE EXCEPTION 'Index collision: index uq_accommodation_enroll_active exists but definition differs: %', v_idx_def;
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END IF;
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ELSE
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RAISE NOTICE 'Creating partial unique index: uq_accommodation_enroll_active';
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CREATE UNIQUE INDEX uq_accommodation_enroll_active
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ON train_accommodation (enrollment_id)
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WHERE accommodation_status IN (0, 1);
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END IF;
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END $$;
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