高水位线问题（High water mark problem）.docVIP

高水位线问题（High water mark problem） When Truncate Table is used, either drop, storage, or reuse storage resets HWM to the first Previous / next 2009-06-26 14:24:56 / personal category: oracle-- space management View (309) / comment (0) / score (0 / 0) My diary Log order: A, B is two Table The data for A and B is placed in the erp_data table space The indexes of A and B are placed in erp_indx table space respectively Then, we use the following two statements to delete the data in the two table Truncate, table, A, drop, storage; Truncate, table, B, reuse, storage; The result will be..: Truncate, table, A, drop, storage; --data: the extent space in the data section will be released (released to minextents extent), and the vacated space can be used by other segment. --index: the index part of the B table will be deleted, and the extent part will be freed, leaving the first extent --hwm: the HWM will be reset to the location of the first Block (HWM will change) Truncate, table, B, reuse, storage; --data: the extent space in the data section will not be recycled (just the data will be deleted), and the freespace space after the data deletion will only be available for use in this table and not for other segment. --index: the index part of the B table deletes data, but retains the extent section --hwm: the HWM will be reset to the location of the first Block (HWM will change) 1, the test starts, build two tables, A, B, and the corresponding index inx_A, idx_B SQL show user USER is QIUYB SQL, create, table, A (col, number); Table created. SQL, insert, into, A, values (1); 1 row created. SQL, insert, into, A, select * from, A; 1 row created. SQL / 2 rows created. SQL / 4 rows created. SQL / 8 rows created. SQL / 16 rows created. SQL / 32 rows created. SQL / 64 rows created. SQL / 128 rows created. SQL / 256 rows created. SQL / 512 rows created. SQL / 1024 rows created. SQL / 2048 rows created. SQL / 4096 rows created. SQL / 8192 rows created. SQL / 16384 rows created. SQL / 327