Here are the lock types:

Table 38. Lock Mode Summary

Lock Mode Applicable Object Type Description

IN (Intent None) Table spaces, tables The lock owner can read any data in
the table, including uncommitted data, but cannot update any of it. No row
locks are acquired by the lock owner. Other concurrent applications can read
or update the table.

IS (Intent Share) Table spaces, tables The lock owner can read data in the
locked table, but not update this data. When an application holds the IS
table lock, the application acquires an S or NS lock on each row read. In
either case, other applications can read or update the table.

NS (Next Key Share) Rows The lock owner and all concurrent applications
can read, but not update, the locked row. This lock is acquired on rows of a
table, instead of an S lock, where the isolation level is either RS or CS on
data that is read.

S (Share) Rows, tables The lock owner and all concurrent applications can
read, but not update, the locked data. Individual rows of a table can be S
locked. If a table is S locked, no row locks are necessary.

IX (Intent Exclusive) Table spaces, tables The lock owner and concurrent
applications can read and update data in the table. When the lock owner
reads data, an S, NS, X, or U lock is acquired on each row read. An X lock
is also acquired on each row that the lock owner updates. Other concurrent
applications can both read and update the table.

SIX (Share with Intent Exclusive) Tables The lock owner can read and
update data in the table. The lock owner acquires X locks on the rows it
updates, but acquires no locks on rows that it reads. Other concurrent
applications can read the table.

U (Update) Rows, tables The lock owner can update data in the locked row
or table. The lock owner acquires X locks on the rows before it updates the
rows. Other units of work can read the data in the locked row or table; but
cannot attempt to update it.

NX (Next Key Exclusive) Rows The lock owner can read but not update the
locked row. This mode is similar to an X lock except that it is compatible
with the NS lock.

NW (Next Key Weak Exclusive) Rows This lock is acquired on the next row
when a row is inserted into the index of a non-catalog table. The lock owner
can read but not update the locked row. This mode is similar to X and NX
locks except that it is compatible with the W and NS locks.

X (Exclusive) Rows, tables The lock owner can both read and update data in
the locked row or table. Tables can be Exclusive locked, meaning that no row
locks are acquired on rows in those tables. Only uncommitted read
applications can access the locked table.

W (Weak Exclusive) Rows This lock is acquired on the row when a row is
inserted into a non-catalog table. The lock owner can change the locked row.
This lock is similar to an X lock except that it is compatible with the NW
lock. Only uncommitted read applications can access the locked row.

Z (Superxclusive) Table spaces, tables This lock is acquired on a table in
certain conditions, such as when the table is altered or dropped, an index
on the table is created or dropped, or a table is reorganized. No other
concurrent application can read or update the table.

Note: Only tables and table spaces will obtain the "intent" lock modes. That
is, intent locks are not obtained for rows.

-----Original Message-----
From: sami dba [mailto:[Email Address Removed] Saturday, June 07, 2003 6:21 AM
To: [Email Address Removed] DB2 Lock question(from db2 exam)



Could some one please confirm the answer?

For which of the following database objects can locks NOT be obtained?

A. A row

B. A table

C. A column

D. An index key


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