Very slow writing BLOB to Oracle DB using Python cx_Oracle

Question

I have a very simple Python application (using cx_Oracle) that is writing a BLOB to an Oracle database, but it is painfully slow when writing large files. My application first downloads an image file from another system using a a SOAP API, and it downloads in a matter of a second or two. However, writing files to the DB of say 100k in size, takes a second or two, but a file of 1.5MB takes just over 1 minute.

My SQL is :-

INSERT INTO my_data (doc_id,doc_content) VALUES (:blobid, :blobdata), blobid=id_variable, blobdata=blob_variable

Is there a reason it's taking so long? Can I speed it up? It oughtn't take more than a few seconds I'd have thought?

(Disclaimer! I have never used cx_Oracle or indeed Oracle itself ever before, I am comparing performance to Postgres which I have used for this kind of thing, and whose performance is infinitely better.)

The full code block is here :-

def upload_docs(doc,blob,conn):
    sql="INSERT INTO my_data (doc_id,doc_content) VALUES (:dociddata, :blobdata)"
    cursor = conn.cursor()
    cursor.execute(sql, dociddata=doc, blobdata=blob)
    conn.commit()
    cursor.close()

conn = cx_Oracle.connect(user="Myuser", password="MyPassword",dsn="ocm.server.here.com:1527/some_name",encoding="UTF-8")
doc_csv = "/tmp/document_list.csv"
csv_file=open(doc_csv, 'r')

for line in csv_file:
splitLineArray = line.split(',')
documentId = splitLineArray[17]

#Pull document down from SOAP API
    documentData = (client.service.getDocument(int(documentId)))        
    upload_docs(documentId, documentData, conn)

Answer 1

Although I haven't quite resolved this, I can now confirm the issue is not with cx_Oracle nor is it an issue with the database itself. I am (or rather, was) connecting to the DB through Oracle Connection Manager, which was causing the delays. When I connect direct to the DB I can write large blobs in around a second. so the issue is definitely with OCM.