如何解决 Postgresql 8.4 错误 'language “plpgsql” already exists'？
How to resolve Postgresql 8.4 error 'language “plpgsql” already exists'?
创建数据库后，我将通过脚本使用 .backup 文件在这个 blank/new 数据库上恢复 PostgreSQL 8.4 中的数据库（使用适当的错误处理） .如果发生任何错误，脚本将中止整个过程并将该过程标记为失败。在数据库还原期间生成以下错误：
pg_restore: connecting to database for restore
pg_restore: creating SCHEMA public
pg_restore: creating COMMENT SCHEMA public
pg_restore: creating PROCEDURAL LANGUAGE plpgsql
pg_restore: [archiver (db)] Error while PROCESSING TOC:
pg_restore: [archiver (db)] Error from TOC entry 302; 2612 16386 PROCEDURAL LANGUAGE plpgsql postgres
pg_restore: [archiver (db)] could not execute query: ERROR: language "plpgsql" already exists
Command was:
CREATE PROCEDURAL LANGUAGE plpgsql;
pg_restore: setting owner and privileges for SCHEMA public
pg_restore: setting owner and privileges for COMMENT SCHEMA public
pg_restore: setting owner and privileges for ACL public
pg_restore: setting owner and privileges for PROCEDURAL LANGUAGE plpgsql
WARNING: errors ignored on restore: 1
Exit code : 1
我知道，这个错误在 PostgreSQL 中应该被忽略 8.x，但是由于我是通过脚本执行的，所以这个问题需要解决，即 PostgreSQL 的退出代码应该是 0，否则，整个过程不会完成。
知道怎么做吗？
我怀疑是否存在优雅的解决方法。每个人都说应该忽略该消息。
一个肮脏的解决方法：在 pg_restore 之前插入一个 DROP LANGUAGE .. 并在之后插入一个 CREATE OR REPLACE LANGUAGE （后者，以防转储不包含 CREATE 语句）
在处理这个问题几个小时后，我发现以下解决方案是基本且简单的。使用命令 'CREATE DATABASE' 创建的数据库默认使用名为 'template1' 的标准系统数据库。相反，使用 'template0'。如 document 中所述：
By instructing CREATE DATABASE to copy template0 instead of template1, you can create a "virgin" user database that contains none of the site-local additions in template1. This is particularly handy when restoring a pg_dump dump: the dump script should be restored in a virgin database to ensure that one recreates the correct contents of the dumped database, without any conflicts with objects that might have been added to template1 later on.
创建数据库后，我将通过脚本使用 .backup 文件在这个 blank/new 数据库上恢复 PostgreSQL 8.4 中的数据库（使用适当的错误处理） .如果发生任何错误，脚本将中止整个过程并将该过程标记为失败。在数据库还原期间生成以下错误：
pg_restore: connecting to database for restore
pg_restore: creating SCHEMA public
pg_restore: creating COMMENT SCHEMA public
pg_restore: creating PROCEDURAL LANGUAGE plpgsql
pg_restore: [archiver (db)] Error while PROCESSING TOC:
pg_restore: [archiver (db)] Error from TOC entry 302; 2612 16386 PROCEDURAL LANGUAGE plpgsql postgres
pg_restore: [archiver (db)] could not execute query: ERROR: language "plpgsql" already exists
Command was:
CREATE PROCEDURAL LANGUAGE plpgsql;
pg_restore: setting owner and privileges for SCHEMA public
pg_restore: setting owner and privileges for COMMENT SCHEMA public
pg_restore: setting owner and privileges for ACL public
pg_restore: setting owner and privileges for PROCEDURAL LANGUAGE plpgsql
WARNING: errors ignored on restore: 1
Exit code : 1
我知道，这个错误在 PostgreSQL 中应该被忽略 8.x，但是由于我是通过脚本执行的，所以这个问题需要解决，即 PostgreSQL 的退出代码应该是 0，否则，整个过程不会完成。
知道怎么做吗？
我怀疑是否存在优雅的解决方法。每个人都说应该忽略该消息。
一个肮脏的解决方法：在 pg_restore 之前插入一个 DROP LANGUAGE .. 并在之后插入一个 CREATE OR REPLACE LANGUAGE （后者，以防转储不包含 CREATE 语句）
在处理这个问题几个小时后，我发现以下解决方案是基本且简单的。使用命令 'CREATE DATABASE' 创建的数据库默认使用名为 'template1' 的标准系统数据库。相反，使用 'template0'。如 document 中所述：
By instructing CREATE DATABASE to copy template0 instead of template1, you can create a "virgin" user database that contains none of the site-local additions in template1. This is particularly handy when restoring a pg_dump dump: the dump script should be restored in a virgin database to ensure that one recreates the correct contents of the dumped database, without any conflicts with objects that might have been added to template1 later on.