Postgresql extension Makefile returning error - postgresql

Question

I wrote a SQL extension following the instructions on PGXN, but I always get a make install error as following:
/bin/mkdir -p '/usr/share/postgresql/9.5/extension'
/bin/mkdir -p '/usr/share/postgresql/9.5/extension'
/bin/mkdir -p '/usr/share/doc/postgresql-doc-9.5/extension'
/usr/bin/install -c -m 644 .//myextname.control '/usr/share/postgresql/9.5/extension/'
/usr/bin/install -c -m 644 .//sql/myextname--1.0.0.sql .//sql/myextname--1.0.0.sql '/usr/share/postgresql/9.5/extension/'
/usr/bin/install: will not overwrite just-created ‘/usr/share/postgresql/9.5/extension/myextname--1.0.0.sql’ with ‘.//sql/myextname--1.0.0.sql’
make: *** [install] Error 1
My Makefile is as following:
EXTENSION = myextname
EXTVERSION = $(shell grep default_version $(EXTENSION).control | \
sed -e "s/default_version[[:space:]]*=[[:space:]]*'\([^']*\)'/\1/")
DATA = $(filter-out $(wildcard sql/*--*.sql),$(wildcard sql/*.sql))
TESTS = $(wildcard test/sql/*.sql)
REGRESS = $(patsubst test/sql/%.sql,%,$(TESTS))
REGRESS_OPTS = --inputdir=test
DOCS = $(wildcard doc/*.md)
MODULES = $(patsubst %.c,%,$(wildcard src/*.c))
PG_CONFIG = pg_config
PG91 = $(shell $(PG_CONFIG) --version | grep -qE " 8\\.| 9\\.0" && echo no || echo yes)
ifeq ($(PG91),yes)
all: sql/$(EXTENSION)--$(EXTVERSION).sql
sql/$(EXTENSION)--$(EXTVERSION).sql: $(strip sql/tables.sql \
sql/types.sql \
sql/domains.sql \
)
cat $^ > $#
DATA = $(wildcard sql/*--*.sql) sql/$(EXTENSION)--$(EXTVERSION).sql
EXTRA_CLEAN = sql/$(EXTENSION)--$(EXTVERSION).sql
endif
PGXS := $(shell $(PG_CONFIG) --pgxs)
include $(PGXS)
This blog says this error is caused by this line:
DATA = $(wildcard sql/*--*.sql) sql/$(EXTENSION)--$(EXTVERSION).sql
which evaluates into the same filename twice (and /usr/bin/install refuses to overwrite the first instance of the file).
But how can I fix it?

Answer 1

You seem to have copied the Makefile from PGXN, and it is probably much more complicated than you need.
For example, do you target PostgreSQL versions below 9.1?
You'll be much better off with a small, simple custom tailored Makefile like this:
MODULES = src/myextname
EXTENSION = myextname
DATA = sql/myextname--1.0.sql
DOCS = doc/myextname.md
REGRESS = myextname
REGRESS_OPTS = --inputdir=test
PG_CONFIG = pg_config
PGXS := $(shell $(PG_CONFIG) --pgxs)
include $(PGXS)
This (untested) Makefile sticks with the file organization suggested by PGXN.