I just heard that Oracle has a feature called External Table that allows to access a flat file (for example a CSV file in the file system) from the database.
I just want to know if there is something similar in DB2 for LUW.
The closest thing I could see is to implement a Table function (written in Java, for example) that will read the file, and return a table with the data from the file. However, this procedure takes a long time (create the Java code, compile the Java and create the function in DB2 associating the Java class) and the implementation is not dynamic for different files with different quantity of columns (table function returns a predefined set of columns).
Here the documentation of Oracle External Tables: http://docs.oracle.com/cd/B28359_01/server.111/b28319/et_concepts.htm
Yes, IBM offers this as part of their InfoSphere Federation Server, which basically allows you to define nicknames inside a database to various data sources. Supported data sources
IBM Db2 11.5 has support for external tables that will allow you to do this.
This was formerly provided only by Netezza and this functionality has made its way to Db2.
See the manual page for CREATE EXTERNAL TABLE here https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.5.0/com.ibm.db2.luw.sql.ref.doc/doc/r_create_ext_table.html
As mentioned, InfoSphere Federation Server is a good choice. There are two alternatives for DB2 UDB (Universal Database), which may be helpful in specific use cases:
DataLinks: it is basically another data type
that keeps a reference to your external file. It also provides
several levels of control over external data such as referential
integrity, access control, coordinated backup and recovery, and
transaction consistency.
DB2 Extenders: they extend functionality of the DB2 to operate on specific file formats, e.g. XML Extender provide set of features to operate on XML files inside DB2
There is also:
(a) external table support in the warehousing engine products (Db2 Warehouse, Db2 Warehouse on Cloud) (b) Data virtualization (aka federation/fluid query) in all Db2 products which may achieve the same thing.
Related
I have created a table using STRSQL, inserted data into the table. Now i want to see the source of the table. Is this possible?
The Database component of ACS, or the older IBM iSeries Access for Windows, has a "Generate SQL" function.
This can be used with DDL defined tables or with DDS defined PF/LF.
In v7.1 (w/ Db PTF level 23) and later, there's a stored procedure, QSYS2.GENERATE_SQL_OBJECTS
Finally, all the above functionality is actually using the Generate Data Definition Language (QSQGNDDL) system API under the covers. You may also call it from your own programs.
We would like to mirror data which is inside SAP to an external database.
Up to now there is a script which exports the data every night.
The customer wants this to happen more often. It should happen every hour.
The export is quite big, and we search for a better way to mirror data which is inside SAP to an external database.
Based on the tag, I assume that your external database is a PostgreSQL database. In this case, I don't think you will really find a pure SAP, database independent solution.
The standard solution for this sort of replication is the SAP SLT Server. It supports taking data out of your SAP system to either a SAP target or a non-SAP target. Currently it supports the following non-SAP targets:
DB2
SAP MaxDB
Microsoft SQL Server
Oracle
Sybase ASE
As you can see, PostgreSQL is not included in there (yet). In conclusion, I see the following possibilities:
Use SLT in combination with some other external DB that is supported.
Use a third party replication tool like for example SymmetricDS.
Depending on your source database, you might be able to use some database specific tools (e.g. SAP HANA Smart Data Integration).
Write some custom code for doing it. In my opinion, you should try to build a sort of log table in this case, to record (using maybe triggers) which rows were inserted / updated / deleted since the last replication. IMO, this should be really a last resort, as database replication is a fairly common topic and you should not reinvent the wheel.
Does DB2 9.7 offer tools to move data between two databases? And only from selected tables? The schema varies slightly between the two, mostly so that the destination database contains some new columns (will be left as null of course) and some columns have changed datatype.
Thanks
You can use federation between the two databases. You create "aliases" from one database in the other one, and then you just perform select or other operations on the remote table. For example, you can use a "load from cursor" using an alias.
Another way to do that, is using db2move or specifically export/import, but you need to deal with files.
Remember, federation is free between db2 databases, no extra license is required.
As part of some requirement, I need to migrate a schema from some existing database to a new schema in a different database. Some part of it is already done and now I need to compare the 2 schema and make changes in the new schema as per gap finding.
I am not using a tool and was trying to understand some details using syscat command but could not get much success.
Any pointer on what is the best way to solve this?
Regards,
Ramakant
A tool really is the best way to solve this – IBM Data Studio is free and can compare schemas between databases.
Assuming you are using DB2 for Linux/UNIX/Windows, you can do a rudimentary compare by looking at selected columns in SYSCAT.TABLES and SYSCAT.COLUMNS (for table definitions), and SYSCAT.INDEXES (for indexes). Exporting this data to files and using diff may be the easiest method. However, doing this for more complex structures (tables with range or database partitioning, foreign keys, etc) will become very complex very quickly as this information is spread across a lot of different system catalog tables.
An alternative method would be to extract DDL using the db2look utility. However, you can't specify the order that db2look outputs objects (db2look extracts DDL based on the objects' CREATE_TIME), so you can't extract DDL for an entire schema into a file and expect to use diff to compare. You would need to extract DDL into a separate file for each table.
Use SchemaCrawler for IBM DB2, a free open-source tool that is designed to produce text output that is designed to be diffed. You can get very detailed information about your schema, including view and stored procedure definitions. All of the information that you need will be output in a single file, and can be compared very easily using a standard diff tool.
Sualeh Fatehi, SchemaCrawler
unfortunately as per company policy, cannot use these tools at this point of time. So am writing some program using JDBC to get the details and do some comparison kind of stuff.
I want to transfer some tables of DB2 to oracle daily for accessing them from web page,
But I don't know commands of DB2. How to do this?
I want this action should perform on database daily on particular time, so is there any tool is available to do this operation. And for writing the program for operating above query which programming language should I use? I am using windows XP.
I think Change Data Capture is used to replicate DML from one database to other databases continuously.
However, what you need is to transfer some data at a particular time each day, thus CDC could be too heavy for that.
You could do a simply "db2 export", and then you could import the generated file from Oracle.
There should be an option to create an adapter in Oracle that permits to query DB2 tables. The opposite is called federation in DB2 (InfoSphere Information Server) that permits to query Oracle tables.
Export http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/topic/com.ibm.db2.luw.admin.cmd.doc/doc/r0008303.html
CMD examples http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/topic/com.ibm.db2.luw.admin.dm.doc/doc/r0004567.html
Check this link
http://blogs.oracle.com/warehousebuilder/entry/simple_change_data_capture_from_db2_table_to_oracle_table
In 11.2 releases, Change Data Capture (CDC) can be done by code template mapping. This allows users to capture the data changes from heterogeneous data source, and load into the target across different platforms.