Postgres vs MySQL: Commands out of sync; - mysql

Question

MySQL scenario:
When I execute "SELECT" queries in MySQL using multiple threads I get the following message: "Commands out of sync; you can't run this command now", I found that this is due to the limitation of having to wait "consume" the results to make another query. C ++ example:
void DataProcAsyncWorker::Execute()
{
std::thread (&DataProcAsyncWorker::Run, this).join();
}
void DataProcAsyncWorker :: Run () {
sql::PreparedStatement * prep_stmt = c->con->prepareStatement(query);
...
}
Important:
I can't help using multiple threads per query (SELECT, INSERT, ETC) because the module I'm building that is being integrated with NodeJS "locks" the thread until the result is already obtained, for this reason I need to run in the background (new thread) and resolve the "promise" containing the result obtained from MySQL
Important:
I am saving several "connections" [example: 10], and with each SQL call the function chooses a connection. This is: 1. A connection pool that contains 10 established connections, Ex:
for (int i = 0; i <10; i ++) {
Com * c = new Com;
c->id = i;
c->con = openConnection ();
c->con->setSchema("gateway");
conns.push_back(c);
}
The problem occurs when executing> = 100 SELECT queries per second, I believe that even with the connection balance 100 connections per second is a high number and the connection "ex: conns.at(10)" is in process and was not consumed
My question:
Does PostgreSQL have this limitation as well? Or in PostgreSQL there is also such a limitation?
Note:
In PHP Docs about MySQL, the mysqli_free_result command is required after using mysqli_query, if not, I will get a "Commands out of sync" error, in contrast to the PostgreSQL documentation, the pg_free_result command is completely optional after using pg_query.
That said, someone using PostgreSQL has already faced problems related to "commands are out of sync", maybe there is another name for this error?
Or is PostgreSQL able to deal with this problem automatically for this reason the free_result is being called invisibly by the server without causing me this error?

Answer 1

You need to finish using one prepared statement (or cursor or similar construct) before starting another.
"Commands out of sync" is often cured by adding the closing statement.

Answer 2

"Question:
Does PostgreSQL have this limitation as well? Or in PostgreSQL there is also such a limitation?"
No, the PostgreSQL does not have this limitation.