Where can one find the high water mark for a table?

最新推荐文章于 2024-01-25 13:35:12 发布

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摘自Orafaq

There is no single system table which contains the high water mark (HWM) for a table. A table's HWM can be calculated using the results from the following SQL statements:

SELECT BLOCKS
FROM   DBA_SEGMENTS
WHERE  OWNER=UPPER(owner) AND SEGMENT_NAME = UPPER(table);

ANALYZE TABLE owner.table ESTIMATE STATISTICS;

SELECT EMPTY_BLOCKS
FROM   DBA_TABLES
WHERE  OWNER=UPPER(owner) AND TABLE_NAME = UPPER(table);

Thus, the tables' HWM = (query result 1) - (query result 2) - 1

NOTE: You can also use the DBMS_SPACE package and calculate the HWM = TOTAL_BLOCKS - UNUSED_BLOCKS - 1.

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