Recommended Suggestions for LLVM

Currently, the LLVM is enabled by default in the database kernel, and users can perform related configurations on it. The overall suggestions are as follows:

1. Set work_mem to an appropriate value and set it to a large value in allowed conditions. If much data is spilled to disks, you are advised to disable the LLVM dynamic compilation and optimization by setting enable_codegen to off).

2. Set codegen_cost_threshold to an appropriate value (The default value is 10000). Ensure that LLVM dynamic compilation and optimization is not used when the data volume is small. After the value of codegen_cost_threshold is set, the database performance may deteriorate due to the use of LLVM dynamic compilation and optimization. In this case, you are advised to increase the parameter value.

3. If a large number of C functions are called, you are advised not to use the LLVM dynamic compilation and optimization.

   NOTE:
   If resources are robust, the larger the data volume is, the better the performance improvement effect is.