INSERT query execution time suddenly slows down

ScyllaDB
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1

INSERT query execution time suddenly slows down when the number of columns is approximately 235 or more.
I would like to know whether this is a problem that can be solved by data modeling or other techniques, or whether it is a performance limitation of ScyllaDB.
If the problem can be solved, I would appreciate it if you could let me know how to do it too.

The composition

  • Node: One (for now)
  • The data type
    • Primary key: text
    • 6 columns common to all tables: text
    • The rest columns: double

The time of INSERT query execution

  • Table A (232 columns total): approx. 0.0007 sec / time.
  • Table B (235 columns total): Average: approx. 0.0095 sec / time [*1].
  • Table C (238 columns total): approx. 0.040 sec / time.
  • Table D (3477 columns total): approx. 0.045 sec / time.

[*1] Most times it takes only 0.0007 sec, but sometimes it takes 0.04 sec.

2

ScyllaDB is not desgien for 3000 columns per table
(See Limits | ScyllaDB Docs)
I suggest revisiting the data modeling.
See here for Wide Table Design Vs. Narrow table design
Data model | ScyllaDB Docs

3

Thanks alot for your info.
I see that there are CQL limits.

  • I created a table with more than 3000 columns and it seems ok except query execution speed. Does the “CQL limits” mean that the behavior is not guaranteed?
  • Also, although I think 230 columns table is in limit, is it just normal for INSERT queries to take longer to execute?
4

Column count has an effect on how expensive it is to merge writes – which translates to time it takes to commit the write to the memtable, as well as to commitlog. You can use UDT:s to improve your latencies, see this blog post for more details: If You Care About Performance Use UDT's