Re: C++, Postgres , libpqxx huge query

To answer my own question, I adapted How to use pqxx::stateless_cursor class
from libpqxx?

try {
work W(*Conn);
pqxx::stateless_cursor<pqxx::cursor_base::read_only,
pqxx::cursor_base::owned>
cursor(W, sql[sqlLoad], "mycursor", false);
/* Assume you know total number of records returned */
for (size_t idx = 0; idx < countRecords; idx += 100000) {
/* Fetch 100,000 records at a time */
result r = cursor.retrieve(idx, idx + 100000);
for (int rownum = 0; rownum < r.size(); ++rownum) {
const result::tuple row = r[rownum];
vid1 = row[0].as<int>();
vid2 = row[1].as<int>();
vid3 = row[2].as<int>();
.............
}
}
} catch (const std::exception &e) {
std::cerr << e.what() << std::endl;
}

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