README.sequence - Additional documentation on manual inserts (using

poweradmin along with other interfaces to the powerdns database).

Removal of "sequence updater"

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Up to poweradmin version 1.2.7-patched, the code included the so

called "sequence updater". It was written to synchronize poweradmin

with the database after manual inserts of zones and records. This

happens if you insert new zones or records by hand, or have other

interfaces than poweradmin talking to the database as well.

The 1.2.7-patched version of poweradmin was using the PEAR::DB module,

using it's nextID() function. It tells the application what will be

the next ID for insertion. However, mysql has "auto_increment" and

pgsql has "serial". Both allow to do insert with ID's created on the

run, without the need of seperate sequence numbers.

In order to get rid of the incidental errors and the need to hit the

"synchronize database" from time to time, the "sequence updater" has

been removed and the code has been updated to use the "auto_increment"

and "serial" functionality. As long as you do manual inserts the

correct way, this will not cause any problems.

Insert new records and zones the correct way (using other tools)

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According to the documentation of powerdns (2.9.20), the id column of

the tables domains and records in a mysql setup are created using the

"auto_increment" option and in a pgsql setup using the "serial"

option. [1] 

This will allow for auto increments of the id field, as long as no one

does a manual insert, specifying the id. So, let's say we have created

a table, one in mysql, one in pgsql:

  CREATE TABLE xmpl_tbl (id INT auto_increment, text TEXT);

  CREATE TABLE xmpl_tbl (id SERIAL PRIMARY KEY, text TEXT);

This insert will work in pgsql only:

  INSERT INTO xmpl_tbl VALUES (DEFAULT,'First insert test");

These inserts will work in mysql only:

  INSERT INTO xmpl_tbl VALUES (NULL,'Third insert test"); 

  INSERT INTO xmpl_tbl VALUES ('','Fourth insert test"); 

This will work in both mysql and pgsql (as long as id didn't exist

already), but it will break "auto increment" feature in pgsql [2] (can

be fixed using setval() functionality in pgsql):

  INSERT INTO xmpl_tbl VALUES (42,'Fifth insert test");

This will work in both mysql and pgsql:

  INSERT INTO xmpl_tbl (text) VALUES ('Second insert test");

So, in other words: if you want to insert records and zones into the

powerdns database using other tools and interfaces than poweradmin,

you should make sure you are using the correct syntax.

Limitations

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Removing the "sequence updater" removes the possibilty to use the

poweradmin code against other databases than mysql and pgsql (or at

least, it is untested).

More information

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More information can be found here:

 - PowerDNS manual, section backends in detail

   <http://downloads.powerdns.com/documentation/html/generic-mypgsql-backends.html>

 - Postgresql documentation, section Operational Questions 

   <http://www.postgresql.org/files/documentation/books/aw_pgsql/node196.html#SECTION0029916000000000000000>

 - pgsql-bugs mailinglist archive

   <http://archives.postgresql.org/pgsql-bugs/2004-11/msg00340.php>

   <http://archives.postgresql.org/pgsql-bugs/2004-11/msg00344.php>