Improved transaction throughput for setups with queued sessions
Details
| Detail name | Value |
|---|---|
| Changelog Number | 19781 |
| Type | Improvement |
| Status | Resolved |
| Fix Versions | Exasol 8.27.0 |
| Resolution Date | 2024-05-02 |
Background
In cases of more than 100 concurrent sessions the Exasol database queues sessions. Those queued sessions wait for a free process to run their next query in.
To improve the availability of free processes and guarantee fairness between active and queued sessions, the Exasol database disconnects active sessions from their process after they finish their current query. These disconnects and process switches introduce overhead and also require certain preconditions like no open result set.
For version 8 we improved Active Session Management to reduce the conditions that prevent process switches. Herein the overhead for process switches was increased. This additional overhead becomes noticeable in high-load setups with more than 100 concurrent sessions and over 100.000 transactions per hour.
Improvement
The overhead was identified and reduced to the level before the optimization.
