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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.
20 lines
636 B
SQL
20 lines
636 B
SQL
-- make sure the prerequisite libraries are loaded
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LOAD 'plpython2';
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SELECT NULL::hstore;
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CREATE FUNCTION hstore_to_plpython2(val internal) RETURNS internal
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LANGUAGE C STRICT IMMUTABLE
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AS 'MODULE_PATHNAME', 'hstore_to_plpython';
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CREATE FUNCTION plpython2_to_hstore(val internal) RETURNS hstore
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LANGUAGE C STRICT IMMUTABLE
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AS 'MODULE_PATHNAME', 'plpython_to_hstore';
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CREATE TRANSFORM FOR hstore LANGUAGE plpython2u (
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FROM SQL WITH FUNCTION hstore_to_plpython2(internal),
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TO SQL WITH FUNCTION plpython2_to_hstore(internal)
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);
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COMMENT ON TRANSFORM FOR hstore LANGUAGE plpython2u IS 'transform between hstore and Python dict';
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