What is Power Architect?

Power Architect is a cross-platform, open-source visual data modeling and profiling tool with a GUI and an embeddable API designed for data architects, DBAs, analysts, and designers.

What does Power Architect allow you to do?

• Maintain a single database schema that works well with multiple database platforms
• Open multiple database sources concurrently
• Drag and drop objects (schemas, tables, columns) into the data modeling playpen to create new models
• Forward engineer data models into new databases on different platforms (Oracle, SQL Server, DB2, PostgreSQL, MySQL)
• Create ETL (Extract, Transform , Load) to use with Kettle ETL to populate the new database
• View and compare data structures and mappings of any two databases
• Generate required DDL statements to synchronize databases
• Create easy-to-read profile summarizing the data contained in the database

You can download Power Architect from the SQL Power Group website or from its Google Code Project Hosting page. I chose the latter since downloading it from the SQL Power Group site requires logging in.

You can run the generic distribution from the command line with the following command:

java -jar $ARCHITECT_HOME/architect.jar

where $ARCHITECT_HOME is the directory where your downloaded architect.jar is located. For large databases, the default memory size limit of 64MB may not be enough. To extend the limit, use the following command which sets the minimum and maximum heap size for your process:

java -Xms512m -Xmx1024m -jar architect.jar

Note: You’ll need the JDBC driver for PostgreSQL to make it work.

Power Architect works for Windows, Mac, and Linux. And the best thing about it – it’s free!

Here are a couple of demos that will show you just how awesome this tool is:

Forward/Reverse Engineering with SQL Power Architect

Data Modeling using SQL Power Architect

Data Profiling using SQL Power Architect

pg_restore: [tar archiver] could not find header for file 2110.dat in tar archive

One possible solution is to use -Fc instead of -Ft. From the man pages, -c means custom:

Output a custom archive suitable for input into pg_restore. This is the most flexible format in that it allows reordering of loading data as well as object definitions. This format is also compressed by default.

and -t means tar:

Output a tar archive suitable for input into pg_restore. Using this archive format allows reordering and/or exclusion of database objects at the time the database is restored. It is also possible to limit which data is reloaded at restore time.

Based on those definitions, I didn’t have a clue that restoring dumps created using the tar format would fail during restoration. I had to spend extra hours just to create a new dump and download it from a remote server.

Maybe I missed some important details from the documentation because after reading it again, I found this:

Members of tar archives are limited to a size less than 8 GB. (This is an inherent limitation of the tar file format.) Therefore this format cannot be used if the textual representation of any one table exceeds that size. The total size of a tar archive and any of the other output formats is not limited, except possibly by the operating system.

If all else fails, read the manual.

After executing

psql -U postgres

and getting this message:

psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket “/tmp/.s.PGSQL.5432″?

It could mean that the postgresql service has not been started (and it could also mean some other things that I haven’t encountered yet). So to start the database, execute the following commands as root:

Initialize the database

service postgresql initdb

Start the PostgreSQL service

/etc/init.d/postgresql start

Then, if I get this message:

psql: FATAL:  Ident authentication failed for user "postgres"

it means I need to edit the last few lines of /var/lib/pgsql/data/pg_hba.conf (this file controls: which hosts are allowed to connect, how clients are authenticated, which PostgreSQL user names they can use, which databases they can access) to look like this:

# TYPE  DATABASE    USER        CIDR-ADDRESS          METHOD

# "local" is for Unix domain socket connections only
local   all         all                               trust
# IPv4 local connections:
host    all         all         127.0.0.1/32          ident sameuser
# IPv6 local connections:
host    all         all         ::1/128               ident sameuser

The change is with the line containing the local connection type, whose method is changed from ident to trust

Then restart the PostgreSQL service:

/etc/init.d/postgresql restart

pg_dump -U postgres -F t -b -v -f ".backup" ""

• -F : --format=format Selects the format of the output.
• t : Output a tar archive suitable for input into pg_restore. Using this archive format allows reordering and/or exclusion of database objects at the time the database is restored. It is also possible to limit which data is reloaded at restore time.
• -b :  --blobs Include large objects in the dump. A non-text output format must be selected.
• -v : Specifies verbose mode. This will cause pg_dump to output detailed object comments and start/stop times to the dump file, and progress messages to standard error.

• -f : --file=file Send output to the specified file. If this is omitted, the standard output is used.

pg_restore -U postgres -d  .backup

If there are better ways to do this, feel free to leave a comment.  Thanks!