append 与 Highwater 测试
2008-06-03 12:43:08 来源:WEB开发网创建测试表:
CE PREFIX = O />
CKGROUND: rgb(217,217,217) 0% 50%; MARGIN: auto auto auto 5.4pt; BORDER-COLLAPSE: collapse; moz-background-clip: -moz-initial; moz-background-origin: -moz-initial; moz-background-inline-policy: -moz-initial" cellSpacing=0 cellPadding=0 border=0> SQL> create table test_block as select * from dba_objects where 1 = 0;
表已创建。
SQL> select OWNER, SEGMENT_NAME, HEADER_FILE, HEADER_BLOCK, BLOCKS, EXTENTS, FREELISTS
2 from dba_segments
3 where segment_name = 'TEST_BLOCK';
SEGMENT_NAME HEADER_FILE HEADER_BLOCK BLOCKS EXTENTS
------------- ----------- ------------ ------- ---------
TEST_BLOCK 11 193 8 1
SQL> select EXTENT_ID, FILE_ID, BLOCK_ID, BYTES, BLOCKS, RELATIVE_FNO
2 from dba_extents
3 where segment_name = 'TEST_BLOCK';
EXTENT_ID FILE_ID BLOCK_ID BYTES BLOCKS RELATIVE_FNO
---------- ---------- ---------- ---------- ---------- ------------
0 11 193 65536 8 11
SQL> insert into test_block select * from dba_objects where rownum< 12;
已创建 11 行。
SQL> select dbms_rowid.rowid_relative_fno(rowid) file#,
2 dbms_rowid.rowid_block_number(rowid) block#
3 from test_block;
FILE# BLOCK#
---------- ----------
11 194
11 194
11 194
11 194
11 194
11 194
11 194
11 194
11 194
11 194
11 194
已选择11行。
数据插入到了第194块。那么,被称为 HEADER_BLOCK 的第193块是做什么的呢?
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