When using the Sakila DB with the Docker image postgres:12.1 the
initialisation fails with:
ERROR: language "plpgsql" already exists
With PostgreSQL 8.4 (see [1]) and earlier it was only possible to
execute:
CREATE [ PROCEDURAL ] LANGUAGE name
Starting with PostgreSQL 9.0 (see [2]) it is possible to execute:
CREATE [ OR REPLACE ] [ PROCEDURAL ] LANGUAGE name
This commit makes the SQL script incompatible with PostgreSQL 8.4
and earlier.
[1] https://www.postgresql.org/docs/8.4/sql-createlanguage.html
[2] https://www.postgresql.org/docs/9.0/sql-createlanguage.html
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