Just turning the crank on the project started in commit d51924be8.
These cases turn out to be exact subsets of the boilerplate needed
for hstore_plpython.
Discussion: <2652.1475512158@sss.pgh.pa.us>
Extension scripts should never use CREATE OR REPLACE for initial object
creation. If there is a collision with a pre-existing (probably
user-created) object, we want extension installation to fail, not silently
overwrite the user's object. Bloom and sslinfo both violated this precept.
Also fix a number of scripts that had no standard header (the file name
comment and the \echo...\quit guard). Probably the \echo...\quit hack
is less important now than it was in 9.1 days, but that doesn't mean
that individual extensions get to choose whether to use it or not.
And fix a couple of evident copy-and-pasteos in file name comments.
No need for back-patch: the REPLACE bugs are both new in 9.6, and the
rest of this is pretty much cosmetic.
Andreas Karlsson and Tom Lane
Commit 866566a690 is insufficient to prevent dump/reload failures
when using transform modules in a database with both plpython2 and
plpython3 installed. The reason is that the transform extension scripts
use DO blocks as a mechanism to pull in the libpython library before
creating the transform function. It's necessary to preload the library
because the dynamic loader won't do it for us on every platform, leading
to "unresolved symbol" failures when the transform library is loaded.
But it's *not* necessary to execute Python code, and doing so will
provoke a multiple-Pythons-are-loaded error even after the preceding
commit.
To fix, use LOAD instead of a DO block. That requires superuser privilege,
but creation of a C function does anyway. It also embeds knowledge of
the underlying library name for each PL language; but that's wired into
the initdb-time contents of pg_pltemplate too, so that doesn't seem like
a large problem either. Note that CREATE TRANSFORM as such doesn't call
the language module at all.
Per a report from Paul Jones. Back-patch to 9.5 where transform modules
were introduced.
This provides a mechanism for specifying conversions between SQL data
types and procedural languages. As examples, there are transforms
for hstore and ltree for PL/Perl and PL/Python.
reviews by Pavel Stěhule and Andres Freund
