Re: DML blocking

Hi We have a customer database on version 19.11.We saw all of sudden most of the session for a INSERT query got blocked and the wait event was showing as "enq: TT - contention [mode=4]" . And the blocking session appeared to be a session executing "ALTER database sql" as below. However , wanted to know if its expected behavior to block application query doing DML on that same tablespace object or we are hitting any bug here? 

I see a doc "Resize Tablespace Hangs with TT Enqueue Contention (Doc ID 2595875.1)", but it says the ALTER statement itself will hang but doesnt tell anything on, if it will imact any DML on the object residing on that tablespace. It's a bigfile tablespace.

alter database datafile '+DATA_XXXX/XXXXX/DATAFILE/data.XXX.XXXXXX' resize 10000G

Pap, do you happen to have something called "Oracle Support"? When your company signs support contract with Oracle Corp. you get something called "Contract Support Identifier" or "CSI" for short. CSI makes it possible to access https://support.oracle.com. When you do that, literally the first thing you encounter is:

Bug 14055559  System hang due to TT enqueue contention with BIGFILE tablespace resize

That seems to match your situation perfectly. Now, the $900,000 question ($1M question with 10% inflation rate): why do I have to access Metalink for you and why can't you access the support page? During the last few months almost every new thread was opened by you. Most of the times, I don't bother and move your posts directly to trash. This time I checked and, sure enough, the answer to your question is trivial to find on Metalink. What's the story here? Am I missing something? Do you have Oracle Support? Are you trying to use this list as a replacement for Oracle Support?

-- 
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com