The difference between dba_segments and dba_tables

CREATE TABLE Tset as SELECT * from Dba_objects;

Select COUNT (*) from Tset;

Select Table_name,blocks,empty_blocks from Dba_tables

where table_name= ' Tset ';

Select Segment_name,bytes,blocks,extents from Dba_segments

where segment_name= ' Tset ';

The problem comes, from dba_tables query blocks is empty, not according to the common sense card Ah ~ ~ What ghost, what Ghost

Select table_name,blocks,empty_blocks,last_analyzed from Dba_tables

where table_name= ' Tset ';

Last_analyzed is an analysis of the time, the null value represents no analysis, so EXECUTE statement analysis under look

Analyze table Tset compute statistics;

1071+80=1151

There seems to be less a blocks, not as if, is less a block. (Let's go ahead and not be sure to find out why).

The above is I found dba_tables and dba_segments the number of blocks inconsistent after the query network obtained;

Probably the individual summarizes the following:

The blocks in 1.dba_segments corresponds to the blocks+empty_blocks in Dba_tables.

2.

The dba_tables view Describes a "logical" structure whiledba_segments describes the "physical" data segm ENT, like a data file.

Also, columns like "blocks" is different between dba_tables and dba_segments. In dba_tables, the "blocks" was calculated when you run Dbms_stats, while indba_segments, ' blocks ' is th e actual number of blocks used by the object on disk.

(not explained, can't explain, I feel just feel understood), attached link: http://www.dba-oracle.com/t_difference_dba_tables_dba_segments.htm

One of the Oracle communities does not use CTAs to create tables to illustrate dba_segments and dba_tables inconsistencies, I repeat:

1. CREATE TABLE Tset1 as SELECT * from Dba_objects where 1=0;

Select Segment_name,bytes,blocks,extents from Dba_segments

where segment_name= ' TSET1 ';

Breaking:

The number of rows in the TSET1 table is 0, the default is assigned a extent, a extent=8 blocks, and a block=8k (65536/1024/8)

is Oracle 11g not a deferred segment assignment (default)?

All right, let's go, next time, this is the end of the interrupt.

2.select table_name,blocks,empty_blocks from Dba_tables where table_name= ' TSET1 ';

Analyze table Tset1 compute statistics;

Select Table_name,blocks,empty_blocks from Dba_tables where table_name= ' TSET1 ';

3.insert to Tset1 select * from Dba_objects;

Commit

4. Select Segment_name,bytes,blocks,extents from Dba_segments

where segment_name= ' TSET1 ';

Select Table_name,blocks,empty_blocks from Dba_tables

where table_name= ' TSET1 ';

Analyze table Tset1 comput statistics;

Select Table_name,blocks,empty_blocks from Dba_tables

where table_name= ' TSET1 ';

1068+83=1151, or not equal to 1152.

Attached to the Oracle Community link, the test results above are equal Oh!

Https://community.oracle.com/thread/582356?start=0&tstart=0

The difference between dba_segments and dba_tables