These days, I'm looking at Tom's Effective Oracle By Design, do some notes, SQL> Create TableSpace TS_TEST DATAFILE SIZE 10240K UNIFORM SIZE 1024K;
TableSpace Created
Executed in 1.021 seconds
SQL> SELECT BYTES / 1024 from DBA_FREE_SPACE WHERE TABLESPACE_NAME = 'TS_TEST';
BYTES / 1024 ---------- 9216
Executed in 0.07 seconds
SQL> SELECT 10240-1024 from Dual
10240-1024 ---------- 9216
Executed in 0.03 seconds
SQL> ALTER DATABASE DATAFILE 'C: /ORACLE/Ordata/orCl/O1_MF_TS_TEST_0ZZF1Z2Y_.DBF' Resize 10304K;
Database altered
Executed in 0.07 seconds
SQL> SELECT BYTES / 1024 from DBA_FREE_SPACE WHERE TABLESPACE_NAME = 'TS_TEST';
BYTES / 1024 ---------- 10240
Executed in 0.02 seconds
Explanation: When a table space is the LMT type, manage the 64K space of the data file header in the table space. We'd better consider this 64K when designing a data file size, otherwise you will waste an extent space. Uniform size assumes 10M, a table space has 20 data files, then waste (10240K-64K) * 20 = 198.75m, saying that it is great, saying that small is not small, of course, now increasingly large storage equipment There is no big problem.
