MySQL C++ Connector crashes at ResultSet->getBlob() - c++

Question

I'm trying to find out how to store binary data from a C++ program in a MariaDB database and restore from there.
For a first try I created a db table DOCUMENT:
idDOCUMENT INT(10) PK
TYPE VARCHAR(45)
DESCRIPTION VARCHAR(45)
CREATIONDATE DATETIME
DATA LONGBLOB
The binary data shall go to the DATA field.
Now I try to upload a PDF document to that table using this C++ code:
ifstream inFile("/home/thomas/Projekte/test-and-trials/test-and-trials/Contract.pdf", ios::binary);
const string INSERTtoDocument = "INSERT INTO DOCUMENT(TYPE,DESCRIPTION,DATA) VALUES(?, ?, ?)";
shared_ptr<sql::PreparedStatement> insertDocument(con->prepareStatement(INSERTtoDocument));
insertDocument->setString(1, "PDF");
insertDocument->setString(2, "Contract");
insertDocument->setBlob(3, &inFile);
int code = insertDocument->executeUpdate();
After executing that I can see in MySQL workbench that a new record has been created.
I can even download the blob from there, view the file in a PDF viewer. diff says that this download is binary same to what I uploaded.
Next I try to download the file using this C++ code:
const string QUERYblob = "SELECT * FROM DOCUMENT WHERE idDOCUMENT=?";
shared_ptr<sql::PreparedStatement> selectDocument(con->prepareStatement(QUERYblob));
selectDocument->setUInt(1, 12);
shared_ptr<sql::ResultSet> res(selectDocument->executeQuery());
res->first();
string docType = res->getString("TYPE");
string docDescr = res->getString("DESCRIPTION");
istream *blobStream = res->getBlob("DATA");
string docType = res->getString("TYPE");
returns "PDF". Correct so far.
string docDescr = res->getString("DESCRIPTION");
gives me "Contract". Also fine.
But
istream *blobStream = res->getBlob("DATA");
crashes with a segment violation. Reliably, each and every time.
Whats going on here?
bt full shows:
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff6f7ba50 in __memcpy_ssse3 () from /lib64/libc.so.6
(gdb) bt full
#0 0x00007ffff6f7ba50 in __memcpy_ssse3 () from /lib64/libc.so.6
No symbol table info available.
#1 0x00007ffff7b939f7 in ?? () from /usr/lib64/libmysqlcppconn.so.7
No symbol table info available.
#2 0x00007ffff7b97658 in sql::mysql::MySQL_Prepared_ResultSet::getString(unsigned int) const () from /usr/lib64/libmysqlcppconn.so.7
No symbol table info available.
#3 0x00007ffff7b9391c in sql::mysql::MySQL_Prepared_ResultSet::getString(sql::SQLString const&) const () from /usr/lib64/libmysqlcppconn.so.7
No symbol table info available.
#4 0x00007ffff7b97f98 in sql::mysql::MySQL_Prepared_ResultSet::getBlob(sql::SQLString const&) const () from /usr/lib64/libmysqlcppconn.so.7
No symbol table info available.
#5 0x0000000000401987 in main () at ../test-and-trials/main.cpp:49
driver = 0x618290
con = std::shared_ptr<sql::Connection> (use count 1, weak count 0) = {
get() = 0x63a500}
res = std::shared_ptr<sql::ResultSet> (use count 1, weak count 0) = {
get() = 0x636b20}
docDescr = "Contract"
buf = std::shared_ptr<char> (empty) = {
get() = 0x6 <error: Cannot access memory at address 0x6>}
docType = "PDF"
outFile = <incomplete type>
QUERYblob = "SELECT * FROM DOCUMENT WHERE idDOCUMENT=?"
selectDocument = std::shared_ptr<sql::PreparedStatement> (use count 1, weak count 0) = {get() = 0x63bde0}
blobStream = 0x402d90 <__libc_csu_init>
--Type <RET> for more, q to quit, c to continue without paging--
blobSize = 0
__FUNCTION__ = "main"
(gdb)