DB2UDB_the_Basics Day 5

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© 2005 IBM Corporation
DB2 UDB Intermediate
Day5

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Topics
 Backup
 Restore
 Load
 Import
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BACKUP
You can choose to backup entire database or one or more table
spaces from within the database.
You can also choose whether you want the backup to be taken
online or offline.
These options can be combined to give you a very flexible recovery
mechanism for your databases.
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Online and Offline Backup
 An online backup allows other applications or processes to
connect to the database as well as read modify the data while the
operation is running.
 An offline backup does not allow other applications or processes
to access the database and their objects while the operation is
being performed.
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Database Backup
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 A database backup is a complete copy of your database objects. In
addition to the data, a backup copy contains information about the
table spaces, containers, the system catalog,database config file,
the log control file, and the recovery history file.
 Important note is that a backup does not contain the dbm cfg file or
the value of registry variables.
 You must have SYSADM, SYSCTRL, or SYSMAINT authority to
perform a backup.

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Commands for Backup
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 db2 backup db dbname
Db2 backup sample
to /db2backup/dir1, /db2backup/dir2
WITH 4 BUFFERS
BUFFER 4096
PARALLELISM 2
• There is no keyword for OFFLINE in the syntax, as this is the
default mode.

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 Db2 BACKUP DATABASE sample ONLINE TO /dev/rdir1, /dev/rdir2
INCLUDE LOGS
 db2 backup db test on all dbpartitionnums
 db2 backup db test on dbpartitionnums (0, 3)
 db2 backup db test on all dbpartitionnums except dbpartitionnums
(1,2)
 db2 backup db test on all dbpartitionnums online INCLUDE LOGS
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Table Space Backup
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In a database where only some of your table spaces change
considerably, you may opt not to back up the entire database but
only specific table spaces. To perform a table space backup, you
can use the following syntax.
 Db2 BACKUP DATABASE sample TABLESPACE (syscatspace,
userspace1, userspace2) ONLINE TO /db2tbsp/backup1,
/db2tbsp/backup2

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Types of Backup
 An incremental backup is a backup image that contains only pages
that have been updated since the previous backup was taken.
 In delta backups, DB2 backs up only the data that has changed
since the last successfull, cumulative, or delta backup.
 For incremental backups, if there was a crash after the incremental
backup on Friday, you would restore the first Sunday’s full backup,
followed by the incremental backup taken on Friday.
 For delta backups, if there was a crash after the delta backup on
Friday, you would restore the first Sunday’s full backup, followed
by each of the delta backups taken on Monday through Friday
inclusive.
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Incremental and Delta Backup
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Trackmod Parameter
 To enable incremental and delta backups, the TRACKMOD
database configuration parameter must be set to YES. This allows
DB2 to track database modifications so that the backup utility can
detect which database pages must be included in the backup
image. After setting this parameter to YES, you must take a full
database backup to have a baseline against which incremental
backups can be taken.
 BACKUP DB sample INCREMENTAL TO /dev/
 BACKUP DB sample INCREMENTAL DELTA TO /dev/rdir1
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Backup Files
The backup images are stored as files. The name of the backup file
contains the following parts:
• Database alias
• Type of backup (0=Full database, 3=Table space, 4=Copy from
LOAD)
• Instance name
• Database partition (always NODE0000 for a single-partition
database)
• Catalog partition number (always CATN0000 for a single-partition
database)
• Timestamp of the backup
• The image sequence number
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Backup file sample
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Restore
 You can restore a database backup image and create a new database or
you can restore over top of an existing database. You need SYSADM,
SYSCTRL, or SYSMAINT authority to restore into an existing database,
and SYSADM or SYSCTRL authority restore to a new database.
 RESTORE DATABASE sample FROM C:DBBACKUP
 TAKEN AT 20070428131259
 WITHOUT ROLLING FORWARD
 WITHOUT PROMPTING
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 If database has archival log enabled .a restore operation puts the
database in to roll forward pending state. Regardless of whether
the backup was online or offline .
 RESTORE DATABASE sample FROM C:DBBACKUP
LOGTARGET C:DB2NODE0000SQL00001SQLOGDIR
Table space Restore :
 RESTORE DATABASE sample (1)
 TABLESPACE ( mytblspace1 ) (2)
 ONLINE (3)
 FROM /db2tbsp/backup1, /db2tbsp/backup2 (4)
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DB2 IMPORT UTILITY
The import utility inserts data from an input file into a table or a
view. The utility performs inserts as if it was executing INSERT
statements.
 import from employee.ixf of ixf
messages employee.out
insert into employee
Messages option is used to record error, warning messages as
well as the import status.
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Import Modes
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Some useful options for Import Utility
 warningcount
 Rowcount
1. import from employee.del of del messages empsalary.out
warningcount 10 replace into empsalary (salary, bonus, comm)
2. import from employee.ixf of ixf messages employee.out
rowcount 1000 replace_create into newemployee
3. import from employee.ixf of ixf messages newemployee.out
create into newemployee in datats index in indexts
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More Useful options for Import
 allow write access – to allow concurrent read/write access to
tables.
 allow no access- table will be locked exclusively.
 commit count – to enforce a commit after every n records imported.
Example :import from employee.ixf of ixf
commitcount 1000
messages newemp.out
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Output of log file
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Restarting failed Import
If you have import failures due to invalid input, for example, you
can use the message file generated from an import command that
uses the commitcount and messages options to identify which
record failed. Then you could issue the same import command with
restartcount n or skipcount n to start the import from record n+1.
This is a very handy
 method to restart a failed import. Here is an example:
import from employee.ixf of ixf commitcount 1000
skipcount 550
messages newemployee.out
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Load Utility
In db2, Load process completes in 4 phases:
• Load
• Build
• Delete
• Index copy
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Load Phase
 During the load phase, the load utility scans the input file for any
invalid data rows that do not comply with the table definition; for
example, if a table column is defined as INTEGER but the input data
is stored as “abcd”. Invalid data will not be loaded into thetable.
and index keys are also collected.
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Build Phase
 During the build phase, indexes are produced
based on the index keys collected during the load
phase. The index keys are sorted during the load
phase, and index statistics are collected (if the
statistics use profile option was specified).
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Delete Phase
 In the load phase, the utility only rejects rows that do not comply
with the column definitions.
 Rows that violated any unique constraint will be deleted in the
delete phase.
 Note that only unique constraint violated rows are deleted. Other
constraints are not checked during this phase or during any load
phase. You have to manually check it after the load operation is
complete.
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Index Copy Phase
 During the index copy phase, index data is copied
from a system temporary table space to the
original table space. This will only occur if a
system temporary table space was specified for
index creation during a load operation with the
read access option
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Messages , Savecount and Warning count Option
 messages option is used to record warnings and errors
encountered during the load operation.
 The savecount option establishes consistency points after every
1,000 rows are loaded.
 Warningcount option will stop when the threshold of warnings is
encountered.
 load from stock.del of del
savecount 1000
warningcount 10 messages stock.out
insert into stock(itemid, itemdesc, cost, inventory)
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Restart and Termination of Load Utility
 Consistency points are established during the load phase. You can
use them to restart a failed or terminated load operation. By
specifying the same load command but replacing insert with the
restart option, the load operation will automatically continue from
the last consistency point.
 To terminate a load, issue the same load command but use the
terminate option in place of insert;
load from stock.del of del
savecount 1000
warningcount 10
messages stock.out terminate
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Modified by dumpfile option
 load from stock.ixf of ixf
 modified by dumpfile=stockdump.dmp
 messages stock.out
 replace into stock
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 As mentioned earlier, the load process goes through four phases.
During the load phase, data that does not comply with the column
definition will not be loaded. Rejected records can be saved in
 a dump file by using the modified by dumpfile modifier. If dumpfile
is not specified,
 rejected records are not saved. Since the load utility will not stop
unless it reaches the warning
 threshold if one is specified, it is not easy to identify the rejected
records. Hence, it is always a good practice to use the modifier and
validate the message file after a load is completed.
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Important Point
 The load utility checks for invalid data and unique constraints
during the load process. However, other constraints such as
referential integrity and check constraints are not validated. DB2
therefore puts target tables defined with these constraints in check
pending state. This forces you to manually validate the data before
the tables are available for further processing
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The COPY YES/NO Options
 Recall that changes made to the target tables during the load are
not logged. This is one of the characteristics of the load utility that
improves performance. However, it also takes away the ability to
perform roll forward recovery for the load operation. DB2 puts the
table space where the target table resides in backup pending state
when the load operation begins.
 After the load completes, you must back up the table space or
database. This ensures that the table space can be restored to the
point where logging is resumed . This is the behavior of the load
option copy no.
 You can also specify copy yes if archival logging is enabled. With copy yes,
a copy of the loaded data will be saved and the table space will not be in
backup pending state upon load completion.
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Thank You
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DB2UDB_the_Basics Day 5

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