表占用分析

```
WITH segment_mapping AS (
    -- 1. 基础表
    SELECT segment_name as table_name, segment_name, segment_type, bytes
    FROM user_segments
    WHERE segment_type LIKE 'TABLE%'
    UNION ALL
    -- 2. 索引对应的表
    SELECT i.table_name, s.segment_name, s.segment_type, s.bytes
    FROM user_segments s
    JOIN user_indexes i ON s.segment_name = i.index_name
    WHERE s.segment_type LIKE 'INDEX%'
    UNION ALL
    -- 3. LOB字段对应的表
    SELECT l.table_name, s.segment_name, s.segment_type, s.bytes
    FROM user_segments s
    JOIN user_lobs l ON s.segment_name = l.segment_name OR s.segment_name = l.index_name
    WHERE s.segment_type LIKE 'LOB%'
)
SELECT
    table_name AS "逻辑业务表名",
    ROUND(SUM(bytes)/1024/1024/1024, 2) AS "总占用(GB)",
    ROUND(SUM(CASE WHEN segment_type LIKE 'TABLE%' THEN bytes ELSE 0 END)/1024/1024/1024, 2) AS "数据(GB)",
    ROUND(SUM(CASE WHEN segment_type LIKE 'INDEX%' THEN bytes ELSE 0 END)/1024/1024/1024, 2) AS "索引(GB)",
    ROUND(SUM(CASE WHEN segment_type LIKE 'LOB%' THEN bytes ELSE 0 END)/1024/1024/1024, 2) AS "大字段(GB)"
FROM
    segment_mapping
GROUP BY
    table_name
ORDER BY
    2 DESC;
```


表空间释放
```

-- 1. 尝试开启行移动（如果报错，通常是因为权限不足或正在被锁定）
ALTER TABLE T_FOC_CREW_MQ_NEW ENABLE ROW MOVEMENT;

-- 2. 尝试收缩空间
-- 先执行压缩数据，不移动高水位线（对业务影响较小）
ALTER TABLE T_FOC_CREW_MQ_NEW SHRINK SPACE COMPACT;

-- 最终收缩并重置高水位线（释放空间给表空间）
ALTER TABLE T_FOC_CREW_MQ_NEW SHRINK SPACE;

```