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With the release of Drupal 6 support for PostgreSQL has come a long way in that core and contrib modules no longer have to know PostgreSQL syntax for CREATE TABLE and other table/index creation or alteration actions.

However when it comes to writing actual SQL in core and contrib modules there will be many situations where SQL that works fine in MySQL will not work in PostgreSQL. Most of the time this is due to the use of MySQL-specific SQL functions or to PostgreSQL's stricter adherence to SQL 92 or SQL 99 standards.

Now that D6 is out it's likely that many module authors will begin to port their modules to D6. With the schema API addition to D6, most authors will assume that PostgreSQL support is included without thinking about the SQL they write in their module functions. For those of us that are PostgreSQL supporters and have the knowledge to help module authors with their SQL this is a great time to make a push for more solid support of PostgreSQL in Drupal.

This Wiki can help to identify different types of SQL that will have problems in PostgreSQL and include solutions if any to these problems. Please add or update anything you think is helpful.