Comment by ugamarkj | Hacker News Reader

Comment by ugamarkj | Hacker News Reader

This got me curious about our Exasol environment, which we've been running since 2016 at Piedmont Healthcare. We average 2 million queries per day (DDL/DML/DQL). Our query failure rate is ~0.1%. Only 7% of those failures were due to hitting resource limits. The rest were SQL issues: constraint errors, data type issues, etc. Average connected users is ~400. Average concurrent queries is ~7 with a daily max average of ~78 concurrent queries. Avg query time across DQL statements is around 10 seconds, which is only that high due to some extreme outliers -- I have users that like to put 200k values in a WHERE clause IN statement, and Tableau sometimes likes to write gnarly SQL with LOD calcs and relationship models.

TPC-H benchmarks are what convinced us to purchase Exasol 10 years ago. Still happy with that decision! Congrats to the Exasol team on these results vs ClickHouse.

Very interesting. What are the bottlenecks you've faced with Exasol?

"200k values in a WHERE clause IN statement"? What is that column about?

Average concurrent query is ~7 in what time period?

As far as bottlenecks, I haven't really hit any in the 10 years we've been using it. Any bottleneck pain points are really user induced. We had some initial system instability during our upgrade from v7 to v8, which was a significant platform architecture change. Those issues have now been resolved. Exasol has pretty good support.

Regarding the 200k values in a where clause, we have some users that will do research across published data source in Tableau. They will copy account IDs from one report and paste them into a filter in another. Our connections from Tableau to Exasol are live. Tableau doesn't have great guardrails on the SQL that gets issued to the database.

The concurrent query comes from a daily statistics table in Exasol. There is an average and max concurrency measure aggregated per day. I averaged the last 30 days. Exasol doesn't really explain their sampling methodology in their documentation: https://docs.exasol.com/db/latest/sql_references/system_tabl...

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