How to reuse tsdpool sessions

[YANGJUHEE521]

Hello, I would like to know how I can use tdspool. and i use freetds-common 1.3.6-1 version

I tested it.

First of all, msql confirmed that there is no session.

2. I turned on tdspool.
   

3. Session from msql to tdspool.
   

4. I thought I would reuse the existing tdspool session if I went in using mypool in tsql, but I had an additional session.
   
   

It's a question.

1. Why couldn't I reuse the session in my test?
2. How to reuse tsdpool sessions
3. Can tdspool be used by on and off processing?
4. How to Log tdspool

[freddy77]

tdspool acts as a man-in-the-middle. So, TSQL (in your example) should connect to tdspool (so on port 25331 in your case) and tdspool will reuse connections.

You can specify log with -l option. Also you can use the TDSDUMP variable (usually very verbose for debugging).

[YANGJUHEE521]

Thank you so much for your reply !!

[YANGJUHEE521]

Hello, as you said, I tried connecting to tdspool, but it slows down in between, not always. Originally, if it didn't take 50ms to import 1 case of data from mssql, there is a case that sometimes takes 500ms. Why does it take 50ms to get 1 case of the same, and when does it take 500ms? How do I improve it?

In addition, using tds is fast, but as you said, using tdspool is sometimes slow.

[freddy77]

Thanks for testing. I would bet on TCP_NODELAY setting (nagle algorithm).

[Gin-9990]

When I looked it up I saw that TCP_NODELAY setting deactivates nagle algorithm and I wanna know its pros&cons
and how to setting a TCP_NODELAY.

[freddy77]

When I looked it up I saw that TCP_NODELAY setting deactivates nagle algorithm and I wanna know its pros&cons and how to setting a TCP_NODELAY.

The base idea of the algorithm is to reduce number of TCP packets. See https://en.wikipedia.org/wiki/Nagle%27s_algorithm. However the TDS protocol already group bytes into larger packets so all you get is an increase of delays and round trips.

[freddy77]

@YANGJUHEE521 in master branch Nagle's algorithm is now turned off. Can you try it ?

[YANGJUHEE521]

@freddy77
Sorry for the late reply. I can't use git because I'm not a test server, but I'm actually testing on a production server that doesn't have access to the internet. So I tried manually finding the part you modified and overwriting it on my server, but it doesn't seem to work. Should I do compile again with the file on the release side? How can I test it? Thank you.

[freddy77]

Hi. Did you solve the issue?
Actually, did the patch helped?
Do you need more work from me?