This configuration parameter dictates the utmost variety of concurrently executing queries permitted inside a ClickHouse server occasion. It serves as an important management mechanism, stopping useful resource exhaustion and making certain system stability. If the variety of incoming queries exceeds this restrict, subsequent queries are queued till present ones full, thereby stopping overload.
Correctly configuring this restrict is paramount for sustaining responsiveness and stopping efficiency degradation. Setting it too excessive can result in extreme useful resource consumption, inflicting reminiscence strain, CPU rivalry, and doubtlessly instability. Conversely, setting it too low can artificially prohibit throughput, leaving system assets underutilized and growing question latency. Traditionally, the necessity for such a mechanism arose from the inherent challenges of managing concurrent workloads in database methods, particularly beneath situations of excessive demand.
