Getting "undefined symbol: Float8GetDatum" when creating function in PostgreSQL - postgresql

Question

I am using postgresql 11.5 in redhat linux 7.3.
In the sql script, the function is created as following:
create or replace function alpine_miner_float_array_sum_accum(state float[], ind float[])
returns float[]
AS 'alpine_miner', 'alpine_miner_float_array_sum_accum'
language C immutable;
But it gives the following error:
ERROR: could not load library "/usr/pgsql-11/lib/alpine_miner.so": /usr/pgsql-11/lib/alpine_miner.so: undefined symbol: Float8GetDatum
SQL state: XX000
I found that /usr/pgsql-11/lib/alpine_miner.so does exist and the output of ld command:
linux-vdso.so.1 => (0x00007ffda65d6000)
libc.so.6 => /lib64/libc.so.6 (0x00007eff25a67000)
/lib64/ld-linux-x86-64.so.2 (0x00007eff26051000)
ldd command:
ld: warning: cannot find entry symbol _start; not setting start address
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `construct_md_array'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `get_call_result_type'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `ArrayGetNItems'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `logf'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `deconstruct_array'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `CurrentMemoryContext'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `acosf'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `GetAttributeByName'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `elog_finish'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `errstart'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `pg_detoast_datum'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `exp'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `sqrtf'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `MemoryContextAllocZero'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `elog_start'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `errmsg'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `BlessTupleDesc'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `get_typlenbyvalalign'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `Float8GetDatum'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `log'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `pow'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `errdetail'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `DatumGetFloat8'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `errfinish'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `sqrt'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `heap_form_tuple'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `format_procedure'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `construct_array'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `MemoryContextAlloc'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `pfree'
/usr/pgsql-11/lib/alpine_miner.so: undefined reference to `errcode'
Any idea with that? Thanks in advance.

Answer 1

When you built alpine_miner.so, you built it against a PostgreSQL installation that was configured differently from the one where you are trying to use it.
In the case of the title problem, alpine_miner.so was built with USE_FLOAT8_BYVAL undefined, but your PostgreSQL has it defined:
#ifdef USE_FLOAT8_BYVAL
static inline Datum
Float8GetDatum(float8 X)
{
union
{
float8 value;
int64 retval;
} myunion;
myunion.value = X;
return Int64GetDatum(myunion.retval);
}
#else
extern Datum Float8GetDatum(float8 X);
#endif
But the list of undefined linker references also suggests that you are trying to load the shared object into a PostgreSQL that is either ancient or modified:
For example, BlessTupleDesc has been in the server since commit 375369acd1c in April 2004.
To get further help, you'll have to disclose the exact make and version of your PostgreSQL and the exact build process for alpine_miner.so.