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List:       postgresql-general
Subject:    concurrent creation of sequences
From:       Marc-Olaf Jaschke <moj () dshare ! de>
Date:       2021-03-31 16:26:52
Message-ID: F385393C-7ADD-45D6-855A-767DFD245006 () dshare ! de
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Hi,

 
I have a use case where I need to create sequences concurrently. I use sequences \
instead of a table with counters to keep lock contention for incrementing the id low. \
The creation of new sequences rarely occurs during normal application operation.

I check via information_schema.sequences if a sequence already exists and catch \
errors that occur with concurrent access if the corresponding sequence already \
exists.  
I wrote a stress test that simulates the behavior with heavy concurrency. I get the \
following three different error codes: 42P07
42710
23505

I would have expected only 42710 (duplicate_object).
 
Is this behavior intentional?
Are there possibly other error codes that the stress test did not uncover and that I \
should consider?  
"create sequence if not exists ..." does not prevent errors with concurrency.
 
 
Tested with "PostgreSQL 12.6 on x86_64-apple-darwin16.7.0, compiled by Apple LLVM \
version 8.1.0 (clang-802.0.42), 64-bit"  
 
Best regards,
Marc-Olaf Jaschke


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