APPEND HINT and TM Enqueue LOCK

During direct-path INSERT, the database obtains exclusive locks on the table (or on all partitions of a partitioned table). As a result, users cannot perform any concurrent insert, update, or delete operations on the table, and concurrent index creation and build operations are not permitted. Concurrent queries, however, are supported, but the query will return only the information before the insert operation.

The behaviour of /*+ APPEND */ hint has changed in the different versions of Oracle:

• In Oracle 10g and previous releases the APPEND hint is ignored when specifying INSERT..VALUES. Thus even though stated, the insert will be done in conventional mode and not use direct-path insert into the buffer cache. When using INSERT..SELECT the hint will be honoured.
  
  
• On 11g Release 1, the APPEND hint will be honoured for an INSERT with VALUES and the row will be inserted directly into datafiles, bypassing the buffer cache.
  
  
• In 11g release 2, a new hint has been added, /*+ APPEND_VALUES */ that will load the data directly into the datafiles.
  

To summarize, there are now 2 different hints for direct-path load:

• APPEND: Instructs Oracle to use direct-path INSERT with the subquery syntax of the INSERT statement.
  
• APPEND_VALUES: Instructs Oracle to use direct-path INSERT with the VALUES clause.
  

INSERT .. VALUES and APPEND HINT

Version: 10.2.0.4 

--SID=159:
SQL> create table test_insert (id number, name varchar2(25));
SQL> insert /*+ APPEND */ into test_insert values (1,'Test1');

1 row created.

select sid,type,id1,id2,lmode from v$lock where sid=159;

SQL>
SID TY ID1 ID2 LMODE
---------- -- ---------- ---------- ----------
159 TM 61245 0 3
159 TX 262153 3571 6

APPEND hint ignored and lock mode=3 Row Exclusive 

Version: 11.1.0.7

--SID=131:
SQL> create table test_insert (id number, name varchar2(25));
SQL> insert /*+ APPEND */ into test_insert values (1,'Test1');

1 row created.

select sid,type,id1,id2,lmode from v$lock where sid=131;

SQL>
SID TY ID1 ID2 LMODE
---------- -- ---------- ---------- ----------
131 TM 84239 0 6
131 TX 65548 4981 6

APPEND hint honoured and lock mode=6 Exclusive 

Version: 11.2.0.3

--SID=59
SQL> create table test_insert (id number, name varchar2(25));
SQL> insert /*+ APPEND */ into test_insert values (1,'Test1');

1 row created.

select sid,type,id1,id2,lmode from v$lock where sid=59;

SID TY ID1 ID2 LMODE
---------- -- ---------- ---------- ----------
69 TM 96843 0 3
69 TX 196640 3301 6

APPEND hint ignored and lock mode=3 Row Exclusive 

INSERT .. VALUES and APPEND_VALUES HINT

Version: 11.2.0.3

--SID=134
SQL> create table test_insert (id number, name varchar2(25));
SQL> insert /*+ APPEND_VALUES */ into test_insert values (1,'Test1');

1 row created.

SQL> select sid,type,id1,id2,lmode from v$lock where sid=134;

SID TY ID1 ID2 LMODE
---------- -- ---------- ---------- ----------
134 TM 96843 0 6
134 TX 65565 7849 6

New APPEND_VALUES  hint honoured and lock mode=6 Exclusive 

INSERT .. SELECT and APPEND HINT 

All Versions

--SID=77
SQL> insert /*+ APPEND */ into test_insert select object_id,object_name from user_objects;

59 rows created.

SQL> select sid,type,id1,id2,lmode from v$lock where sid=77;

SID TY ID1 ID2 LMODE
---------- -- ---------- ---------- ----------
77 TM 96843 0 6
77 TX 589827 8029 6

APPEND hint honoured and lock mode=6 Exclusive