Oracle data pump
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Transcript of Oracle data pump
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Data Pump Overview
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What is Data Pump?
A replacement of the traditional export/import utilities?
The evolution of the traditional export/import utilities?
A completely new 10g utility serving a similar yet slightly different purpose?
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Other Options for Moving Data
Traditional Export and ImportPros
Easy to use – most DBAs have years of experience using these utilities
Versatile – various options available; can specify what to include
Platform independent
Serial output
Cons Comparatively slow
Can be network intensive
Non-interruptible / resumable
Limited filtering options (for example, can exclude just VIEWS)
Limited remapping options (i.e. from one tablespace to another)
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Other Options for Moving Data
Transportable TablespacesPros
Undoubtedly the fastest way to move data
Can use the traditional exp/imp or Data Pump to move meta-data
Cross-platform support if the platform byte-order is the same
Cons Tablespaces must be made read-only
Not selective (must move the entire tablespace)
Flashback is not possible (tablespace is read only when copied)
No physical reorganization is performed
Datafile sizes remain constant
Must use RMAN to convert the datafile if migrating to a platform with a different byte-order (check V$TRANSPORTABLE_PLATFORM)
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Other Options Used Less Frequently
Extraction to a flat file and loading using SQL Loader
Direct copy using database links (SQL Plus COPY command)
Oracle Streams
3rd Party data ETL or reorg tools
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Top 10 Reasons to Love DataPump
10. Similar look and feel to the old exp/imp
11. Can filter on the full range of object types
12. Can re-map datafiles and or tablespaces on import
13. Estimates the export file size (space needed)
14. Parallelizable
15. Significantly faster than the traditional exp/imp
16. PL/SQL Interface – programmable
17. A file is not actually required - can import through a network link
18. Track in v$session_longops
19. Resumable (interruptible and restartable)
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Top 10 Reasons Not to Love Data Pump
10. Still generates redo (unlike direct path inserts)
11. Aggregation of exported data is not possible (sort only)
12. Performance on the server
13. Harder to tell what it’s doing at any given time
14. No equivalent to the STATISTICS option
15. Cannot be used with sequential media such as tapes and pipes (not read/written serially)
16. Only accesses files on the server, never the client
17. Oracle directories are required in the DB to access the files
18. Does not support COMMIT on imp or CONSISTENT on exp
19. If constraints are violated on import, the load is discontinued
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Operation Fundamentals
Export/ImportThese utilities would basically connect to the Oracle database
via Oracle NET and run queries or DDL/DML
Processing of returned results and I/O operations were done on the client
Data PumpThe executables call PL/SQL APIs
Therefore processing is done on the database server
This can be an advantage or a disadvantage depending on the situation
“Self-Tuning”: no longer need to use BUFFER or RECORDSET
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Export Operation
Network
Export File(s)
exp.exe
Oracle Database
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Data Pump Export Operation
Network
Export File(s)
expdp.exe
Oracle Database
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Key Differences
Dump and log files are on the server, not the client
Must have a DIRECTORY created in the Oracle database for I/OPermissions for the userid connecting to the instance, not the
schemas being exported or imported
Canceling the client process does not stop the job
Doesn’t automatically overwrite dump file if it already exists – returns an error instead
Parameters (command line) are reported in the log file
Exported objects order based on table size (descending) instead of alphabetically
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Multiple Interfaces
1. Command line utilities expdb and impdb Similar to the familiar exp and imp in usage
Use HELP=Y for a list of commands
Oracle documentation provides a comparison table to exp/imp
2. Enterprise Manager
3. PL/SQL Can be used independently but is difficult
All of these call the DBMS_DATAPUMP API Uses Oracle Advanced Queuing
Uses DBMS_METADATA
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Unload Mechanisms
Data Pump automatically chooses to unload data either using:Direct path
External Tables (new driver called ORACLE_DATAPUMP)
Same “External Tables” mechanism that was introduced in Oracle9i
When will it use External tables:When parallelism can be used
When the table contains a complex data type or structure that prevents direct path unloads A lot of tables fall under this situation – see Oracle documentation for a
complete list
It doesn’t really matter to us which method is used
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Multiple Processes
Master Control ProcessSpawns worker processes
Populates the master control table and log file
The master control table can be queried to track the job’s process
At the end of an export, the master control table is written to the dump file and dropped from the database
Worker ProcessesPerforms the loading/unloading
Number of processes depends on the degree of parallelism (the PARALLEL option)
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Detaching and Re-Attaching
Issuing “Ctrl-C” from the data pump import will detachImport is running on the server so it will continue
Brings you into “interactive-command” mode
To re-attach, run impdp with the ATTACH= optionExample: impdp userid=system/oracle attach=JOB_01
Brings you back into “interactive-command” mode
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New Views
DBA_DATAPUMP_JOBS and USER_DATABASE_JOBSIdentify all jobs regardless of their state
Identify any master tables not associated with an active job
DBA_DATAPUMP_SESSIONSIdentify user sessions that are attached to a job
Data pump sessions populate v$session_longopsDocumentation says that it is 100% accurate for imports but
testing proves otherwise!!!
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Security Considerations
Still uses the EXP_FULL_DATABASE and IMP_FULL_DATABASE
A privileged user will have these two roles
A privileged user can:Export/import objects owned by other schemas
Export non-schema objects (metadata)
Attach to, monitor, and control jobs initiated by others
Perform schema, datafile, and tablespace remapping
Similar to the traditional export/import
Supports label securityIf exporting user has the EXEMPT ACCESS POLICY role
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Object Statistics
From Oracle documentation regarding data pump exports:“A parameter comparable to STATISTICS is not needed.
Statistics are always saved for tables.”
From Oracle documentation regarding data pump imports:“A parameter comparable to STATISTICS is not needed. If the
source table has statistics, they are imported.”
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Other Random Points
Can still use a parameter file and the PARFILE command line option
Fully supports Automatic Storage Management (ASM)
Can still flashback to a specified time or SCN
Can still extract (or backup) DDL (meta data)Using the SQLFILE option instead of the traditional INDEXFILE or SHOW options
Full support of LOBS