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Adding notnull fields to Oracle11g is faster than 10g-New Features

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Adding notnull fields to Oracle11g is faster than 10g-New Features

Adding a not null field before 11g is very slow, and it is very fast after 11g. We will first perform a test and then explore the principle.

SQL> select * from v $ version;

BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0-64bi
PL/SQL Release 10.2.0.1.0-Production
CORE 10.2.0.1.0 Production
TNS for 64-bit Windows: Version 10.2.0.1.0-Production
NLSRTL Version 10.2.0.1.0-Production

SQL> drop table test purge;
SQL> create table test as select * from dba_objects;
SQL> select count (*) from test;
COUNT (*)
----------
151203
SQL> set timing on
SQL> alter table test add col1 char (1000) DEFAULT 'large column' not null;
Used time: 00: 00: 09.48

SQL> SELECT SUM (BYTES)/1024/1024 | 'M' FROM user_segments WHERE segment_name = 'test ';
SUM (BYTES)/1024/1024 | 'M'
-----------------------------------------
200 M

Under 11g:
SQL> select * from v $ version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0-64bit Production
PL/SQL Release 11.2.0.1.0-Production
CORE 11.2.0.1.0 Production
TNS for Linux: Version 11.2.0.1.0-Production
NLSRTL Version 11.2.0.1.0-Production
SQL> drop table test purge;
SQL> create table test as select * from dba_objects;
SQL> insert into test select * from dba_objects;
SQL> commit;
SQL> select count (*) from test;
COUNT (*)
----------
149012
SQL> set timing on
SQL> alter table test add col1 char (1000) DEFAULT 'large column' not null;

Used time: 00: 00: 00.07

SQL> SELECT SUM (BYTES)/1024/1024 | 'M' FROM user_segments WHERE segment_name = 'test ';
SUM (BYTES)/1024/1024 | 'M'
-----------------------------------------

18 M

Exploring principle: dump block can be found that many row migration and row links are generated at 10 Gb. In the official document, Oracle records the DEFAULT value in the data dictionary to avoid heavy update operations.

Look at the dump block:
Alter session set tracefile_identifier = 'gg _ test ';
Select rowid,
Dbms_rowid.rowid_object (rowid) object_id,
Dbms_rowid.rowid_relative_fno (rowid) file_id,
Dbms_rowid.rowid_block_number (rowid) block_id,
Dbms_rowid.rowid_row_number (rowid) num
From test where rownum <5;
Alter system dump datafile 5 block 1465683;

10 GB:
Tl: 9 fb: -- H ----- lb: 0x2 cc: 0
Nrid: 0x0181e36b. 1
Tab 0, row 2, @ 0x1b3a
Tl: 1076 fb: -- H-FL -- lb: 0x2 cc: 14
Col 0: [3] 53 59 53
Col 1: [4] 43 4f 4e 24
Col 2: * NULL *
Col 3: [2] c1 1d
Col 4: [2] c1 1d
Col 5: [5] 54 41 42 4c 45
Col 6: [7] 78 69 08 1e 0e 33 19
Col 7: [7] 78 69 08 1e 0f 31 37
Col 8: [19] 32 30 30 35 2d 30 38 2d 33 30 3a 31 33 3a 35 30 3a 32 34
Col 9: [5] 56 41 4c 49 44
Col 10: [1] 4e
Col 11: [1] 4e
Col 12: [1] 4e
Col 13: [2, 1000]
4c 41 52 47 45 20 43 4f 4c 55 4d 4e 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20
Tab 0, row 3, @ 0x1b31
Tl: 9 fb: -- H ----- lb: 0x2 cc: 0
Nrid: 0x0181e36b. 2 -- nrid row migration
Tab 0, row 4, @ 0x1b28
Tl: 9 fb: -- H ----- lb: 0x2 cc: 0
Nrid: 0x0181e36b. 3

Under 11g:
Tab 0, row 0, @ 0x3f33
Tl: 77 fb: -- H-FL -- lb: 0x0 cc: 14
Col 0: [3] 53 59 53
Col 1: [5] 49 43 4f 4c 24
Col 2: * NULL *
Col 3: [2] c1 15
Col 4: [2] c1 03
Col 5: [5] 54 41 42 4c 45
Col 6: [7] 78 72 06 09 0c 1a 2f
Col 7: [7] 78 72 06 09 0c 26 33
Col 8: [19] 32 30 31 34 2d 30 36 2d 30 39 3a 31 31 3a 32 35 3a 34 36
Col 9: [5] 56 41 4c 49 44
Col 10: [1] 4e
Col 11: [1] 4e
Col 12: [1] 4e
Col 13: [2] c1 02
Tab 0, row 1, @ 0x3ee4
Tl: 79 fb: -- H-FL -- lb: 0x0 cc: 14
Col 0: [3] 53 59 53
Col 1: [7] 49 5f 55 53 45 52 31
Col 2: * NULL *
Col 3: [2] c1 2f
Col 4: [2] c1 2f
Col 5: [5] 49 4e 44 45 58
Col 6: [7] 78 72 06 09 0c 1a 2f
Col 7: [7] 78 72 06 09 0c 1a 2f
Col 8: [19] 32 30 31 34 2d 30 36 2d 30 39 3a 31 31 3a 32 35 3a 34 36
Col 9: [5] 56 41 4c 49 44
Col 10: [1] 4e
Col 11: [1] 4e
Col 12: [1] 4e
Col 13: [2] c1 05

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