DELETE FROM large_table WHERE condition;

-- MySQL示例
DELETE FROM large_table WHERE condition LIMIT 1000;

-- SQL Server示例
WHILE 1=1
BEGIN
    DELETE TOP (1000) FROM large_table WHERE condition;
    IF @@ROWCOUNT = 0 BREAK;
END

-- 1. 创建临时表存储要保留的数据
CREATE TABLE temp_table AS SELECT * FROM large_table WHERE keep_condition;

-- 2. 截断原表
TRUNCATE TABLE large_table;

-- 3. 将保留数据插回原表
INSERT INTO large_table SELECT * FROM temp_table;

-- 4. 删除临时表
DROP TABLE temp_table;

-- 如果是按日期分区的表
ALTER TABLE large_table DROP PARTITION old_data_partition;

DO $$
DECLARE
  batch_size INTEGER := 1000;
  rows_affected INTEGER := batch_size;
BEGIN
  WHILE rows_affected > 0 LOOP
    DELETE FROM large_table 
    WHERE id IN (
      SELECT id 
      FROM large_table 
      WHERE condition
      LIMIT batch_size
    );
    
    GET DIAGNOSTICS rows_affected = ROW_COUNT;
    COMMIT;
    RAISE NOTICE 'Deleted % rows', rows_affected;
    
    -- 添加延迟以减少系统负载
    PERFORM pg_sleep(0.1);
  END LOOP;
END $$;

DECLARE
  CURSOR c IS SELECT rowid FROM large_table WHERE condition;
  TYPE rowid_array IS TABLE OF ROWID;
  l_rowids rowid_array;
  l_batch_size NUMBER := 1000;
BEGIN
  OPEN c;
  LOOP
    FETCH c BULK COLLECT INTO l_rowids LIMIT l_batch_size;
    EXIT WHEN l_rowids.COUNT = 0;
    
    FORALL i IN 1..l_rowids.COUNT
      DELETE FROM large_table WHERE rowid = l_rowids(i);
    
    COMMIT;
    DBMS_OUTPUT.PUT_LINE('Deleted ' || l_rowids.COUNT || ' rows');
  END LOOP;
  CLOSE c;
END;