[postgis-users] pg_dumpall Fails: No $libdir/postgis-2.0

[Brian Allen]

I have a database that has had PostGIS in it since 1.5.  We've
upgraded through various Postgres and PostGIS versions until I'm
currently on:

PostgreSQL 9.2.10 on x86_64-unknown-linux-gnu, compiled by gcc (GCC)
4.4.7 20120313 (Red Hat 4.4.7-11), 64-bit POSTGIS="2.1.5 r13152"
GEOS="3.4.2-CAPI-1.8.2 r3921" PROJ="Rel. 4.8.0, 6 March 2012"
GDAL="GDAL 1.9.2, released 2012/10/08" LIBXML="2.7.6" LIBJSO
N="UNKNOWN" TOPOLOGY RASTER

Everything works fine.

But I'm upgrading to Postgres 9.4, so I'm backing up the cluster using
pg_dumpall.

It fails with:

pg_dump: [archiver (db)] query failed: ERROR:  could not access file
"$libdir/postgis-2.0": No such file or directory
pg_dump: [archiver (db)] query was: SELECT a.attnum, a.attname,
a.atttypmod, a.attstattarget, a.attstorage, t.typstorage,
a.attnotnull, a.atthasdef, a.attisdropped, a.attlen, a.attalign,
a.attislocal, pg_catalog.format_type(t.oid,a.atttypmod) AS atttypname,
array_to_string(a.attoptions, ', ') AS attoptions, CASE WHEN
a.attcollation <> t.typcollation THEN a.attcollation ELSE 0 END AS
attcollation, pg_catalog.array_to_string(ARRAY(SELECT
pg_catalog.quote_ident(option_name) || ' ' ||
pg_catalog.quote_literal(option_value) FROM
pg_catalog.pg_options_to_table(attfdwoptions) ORDER BY option_name),
E',
    ') AS attfdwoptions FROM pg_catalog.pg_attribute a LEFT JOIN
pg_catalog.pg_type t ON a.atttypid = t.oid WHERE a.attrelid =
'18040917'::pg_catalog.oid AND a.attnum > 0::pg_catalog.int2 ORDER BY
a.attrelid, a.attnum

If I run that query in psql it succeeds, but returns no rows.

What in my schema is directly tied to PostGIS 2.0?  This has happened
before when upgrading and I have to track down the old version,
downgrade, do the backup, upgrade, then restore. It's a major pain,
and as time goes on it gets harder and harder to find the old versions
or have them work with CentOS (currently 6.6).

In my current case, I'll have to downgrade to postgis2_91-2.0.6
because it complains that I don't have "rtpostgis-2.0".

What in my schema is still pointing to or requiring rtpostgis-2.0?
Why won't it work with the current version of PostGIS that is
installed and working?

I think I can figure it out for this upgrade, but what about next
time, and the time after that?

Thanks!