Connection: Slowness in Query execution

Good morning, I have a query (WITH... 5 sub-querys) that I execute with TOAD (Stable and BETA version) and it took around 17 minutes.

I have run the same on other tools and the result was 18 seconds.

I started checking and verified that the difference was in the way of connecting to the database.

Without using the Oracle client it takes 17 minutes.
With Oracle Client it takes 18 seconds.




  • Windows 10 64b
  • Toad 64b (versión Stable y Beta)

As you probably know, Toad does not execute the queries - Oracle does. There must be some database setting that your client is applying that Toad is not. I don't think login.sql or glogin.sql would come into play here but it must be something like that. Maybe something in sqlnet.ora?

Hi John !

What difference is there in making the connection using the Oracle client and without using it?

I understand that when using the Oracle client (check in Oracle Client) the connection uses the configuration files found on the client PC (tsnames, sqlnet.ora, etc.)

When the Oracle client is NOT used (without checking in Oracle Client) how is the connection made?
What steps are followed to connect to the database?

Thanks John

We have some code (from a 3rd party vendor) that basically mimics the Oracle client DLLs.

I don't know exact steps to give you. I'll post a message on their forum and see if they have any ideas. I'll send you a private message with a link to the post. If they ask for any details, feel free to jump in over there.

Thank you very much John!


Hi Carlos.

I think I found out why you are seeing different performance with/without an Oracle client. I think it is related to this: Bind variable peeking doesn't work - #17 by JohnDorlon

In Toad 17.1, you can set Options -> Oracle -> General -> OCI Array Buffer Size to "Manual" and then I think you'll see the same performance both with and without an Oracle client.


Excellent John!
Now I'm out of the office, as soon as I can I'll try it.

Thank you very much John!

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