This PR simply adds the columns to pg_dist_object and
implements the necessary metadata changes to keep track of
distribution argument of the functions/procedures.
This PR aims to add the minimal set of changes required to start
distributing functions. You can use create_distributed_function(regproc)
UDF to distribute a function.
SELECT create_distributed_function('add(int,int)');
The function definition should include the param types to properly
identify the correct function that we wish to distribute
@thanodnl told me it was a bit of a problem that it's impossible to see
the history of a UDF in git. The only way to do so is by reading all the
sql migration files from new to old. Another problem is that it's also
hard to review the changed UDF during code review, because to find out
what changed you have to do the same. I thought of a IMHO better (but
not perfect) way to handle this.
We keep the definition of a UDF in sql/udfs/{name_of_udf}/latest.sql.
That file we change whenever we need to make a change to the the UDF. On
top of that you also make a snapshot of the file in
sql/udfs/{name_of_udf}/{migration-version}.sql (e.g. 9.0-1.sql) by
copying the contents. This way you can easily view what the actual
changes were by looking at the latest.sql file.
There's still the question on how to use these files then. Sadly
postgres doesn't allow inclusion of other sql files in the migration sql
file (it does in psql using \i). So instead I used the C preprocessor+
make to compile a sql/xxx.sql to a build/sql/xxx.sql file. This final
build/sql/xxx.sql file has every occurence of #include "somefile.sql" in
sql/xxx.sql replaced by the contents of somefile.sql.