[PERFORM] performance libpq vs JDBC

[Werner Scholtes]

I wrote a test program in C++ using libpq. It works as follows (pseudo code):

for ( int loop = 0; loop < 1000; ++loop ) {
   PQexec("BEGIN");
   const char* sql = "INSERT INTO pg_perf_test (id, text) VALUES($1,$2)";
   PQprepare(m_conn, "stmtid",sql,0,NULL);
   for ( int i = 0; i < 1000; ++i )
      // Set values etc.
      PQexecPrepared(m_conn,...);
   }
   PQexec("DEALLOCATE stmtid");
   PQexec("COMMIT");
}

I measured the duration of every loop of the outer for-loop resulting in an 
average of 450 ms (per 1000 data sets insert)

After that, I wrote a test program in Java using JDBC. It works as follows:

for ( int loops = 0; loops < 1000; ++i) {
   String sql = "INSERT INTO pq_perf_test (id,text) VALUES (?,?)";
   PreparedStatement stmt = con.prepareStatement(sql);
   for (int i = 0; i < 1000; ++i ) {
      // Set values etc.
      stmt.addBatch();
   }
   stmt.executeBatch();
   con.commit();
   stmt.close();
}

I measured the duration of every loop of the outer for-loop resulting in an 
average of 100 ms (per 1000 data sets insert)

This means that accessing PostgreSQL by JDBC is about 4-5 times faster than 
using libpq.

Comparable  results have been measured with analog update and delete statements.

I need to enhance the performance of my C++ code. Is there any possibility in 
libpq to reach the performance of JDBC for INSERT, UPDATE and DELETE statements 
(I have no chance to use COPY statements)? I didn't find anything comparable to 
PreparedStatement.executeBatch() in libpq.

Best regards,
Werner Scholtes