添加 oracle/oracle表占用分析.md

oracle/oracle表占用分析.md

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+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;
+
+```
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