ARTICLE AD BOX
I’m trying to efficiently read about 10 million rows (single column) from a database table in Python and I’m not sure if my current approach is reasonable or if I’m missing some optimizations.
Approach 1: cursor + fetchmany On average, it takes around 1.2 minutes to read 10 million rows.
sql = f"SELECT {col_id} FROM {table_id}" raw_conn = engine.raw_connection() try: cursor = raw_conn.cursor() cursor.execute(sql) total_rows = 0 while True: rows = cursor.fetchmany(chunk_size) if not rows: break # Direct string conversion - fastest approach values.extend(str(row[0]) for row in rows)Approach 2: pandas read_sql with chunks
On average, this takes around 2 minutes to read 10 million rows.
What is the most efficient way to read this many rows from the table into Python?
Are these timings (~1.2–2 minutes for 10 million rows) reasonable, or can this be significantly improved with a different pattern (e.g., driver settings, batching strategy, multiprocessing, or a different library)?
