tidb_mem_quota_query

tidb_mem_quota_query is a configuration parameter in TiDB, an open-source distributed NewSQL database, that determines the maximum amount of memory that can be used for query execution.

TiDB uses a two-level memory management mechanism: global memory and local memory. The tidb_mem_quota_query parameter specifically controls the maximum amount of memory that can be allocated for query processing in the global memory. This includes memory used for storing intermediate results, sorting, joining, aggregating, and other query-related operations.

By setting an appropriate value for tidb_mem_quota_query, users can control the memory consumption of query execution and prevent excessive memory usage that may lead to performance degradation or out-of-memory errors. The default value of this parameter is 32GB.

It is worth noting that tidb_mem_quota_query is a dynamic configuration parameter, which means it can be modified during runtime without restarting the TiDB server. However, changing the value of this parameter may affect the performance of running queries, so it should be adjusted carefully based on the available system resources and workload characteristics