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The former approach used ExclusiveLock on pg_database, which being a cluster-wide lock meant only one of these operations could proceed at a time; worse, it also blocked all incoming connections in ReverifyMyDatabase. Now that we have LockSharedObject(), we can use locks of different types applied to databases considered as objects. This allows much more flexible management of the interlocking: two CREATE DATABASEs need not block each other, and need not block connections except to the template database being used. Similarly DROP DATABASE doesn't block unrelated operations. The locking used in flatfiles.c is also much narrower in scope than before. Per recent proposal.
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces including some of the more common listed below: C++ - http://thaiopensource.org/development/libpqxx/ JDBC - http://jdbc.postgresql.org ODBC - http://odbc.postgresql.org Perl - http://search.cpan.org/~dbdpg/ PHP - http://www.php.net Python - http://www.initd.org/ Ruby - http://ruby.scripting.ca/postgres/ Other language binding are available from a variety of contributing parties. PostgreSQL also has a great number of procedural languages available, a short but not complete list is below: pl/c - Included in PostgreSQL core plPgsql - Included in PostgreSQL core - Similar to Oracle PL/sql plPerl - Included in PostgreSQL core plPHP - http://projects.commandprompt.com/projects/public/plphp plPython - Included in PostgreSQL core plJava - http://gborg.postgresql.org/project/pljava/projdisplay.php plTcl - Included in PostgreSQL core See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Changes between all PostgreSQL releases are recorded in the file HISTORY. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.