MySQL Dump and Recreate

Here's a little post so I don't forget to dump and recreate a MySQL database.

To dump a database:

$ mysqldump -uroot -ppassword mydb > mydb.mysql

To recreate the database:

$ mysqladmin -uroot -ppassword drop mydb
$ mysqladmin -uroot -ppassword create mydb
$ mysql -uroot -ppassword mydb < mydb.mysql

/usr/bin/ld: cannot find -lperl

I was trying to install pp, the Perl PAR Packager:

$ sudo cpan pp

I got this error:

/usr/bin/ld: cannot find -lperl
collect2: ld returned 1 exit status
make[1]: *** [par] Error 1
make[1]: Leaving directory `/home/prystasj/.cpan/build/PAR-Packer-0.982-zX8GIO/myldr'
make: *** [subdirs] Error 2
  SMUELLER/PAR-Packer-0.982.tar.gz
  /usr/bin/make -- NOT OK
Running make test
  Can't test without successful make
Running make install
  Make had returned bad status, install seems impossible

I saw a suggestion to install libperl-dev, but I had that package already up-to-date.
By changing this symlink in /usr/lib from:

lrwxrwxrwx 1 root root 15 2009-01-23 15:28 /usr/lib/libperl.so -> libperl.so.5.10

To:

lrwxrwxrwx 1 root root 15 2009-01-23 15:28 /usr/lib/libperl.so -> libperl.so.5.10.0

I was able to install pp:

$ which pp
/usr/local/bin/pp

JPA: Retrieving ID of Recently Persisted Object

Using JPA with an orm.xml, I was having trouble retrieving the primary key (id) of a recently persisted object. The entity in my orm.xml:

<entity class="Foo" name="Foo" access="FIELD">
 <table name="Foo"/>
 <attributes>
   <id name="id">
     <column name="ID" nullable="false"/>
     <generated-value strategy="SEQUENCE"/>
   </id>
   ...
  </table>
</entity>

The relevant MySQL for the table:

CREATE TABLE FOO
(
  ID       INT              NOT NULL AUTO_INCREMENT,
...
  PRIMARY KEY(ID)
)

Regardless of whether or not the id property was null or not, it was not updated after the following call to persist():

Foo foo = new Foo();
getJpaTemplate().persist(foo);
if (logger.isDebugEnabled())
  logger.debug(foo.getId()) // null

Adding a call to flush() however ended up giving me the id:

Foo foo = new Foo();
getJpaTemplate().persist(foo);
getJpaTemplate().flush();
if (logger.isDebugEnabled())
  logger.debug(foo.getId()) // outputs the assigned id

I'm not sure why the flush() was necessary. A similar issue is also discussed here: Spring Forums Post.