[Feature]: Evaluate Profile-Guided Optimization (PGO) and LLVM BOLT

Hi!

Recently I did many Profile-Guided Optimization (PGO) benchmarks on multiple projects (including many databases like PostgreSQL, MongoDB, Redis, and many others) - the results are available here, all databases results are located here. So that's why I think it's worth trying to apply PGO to OceanBase.

I can suggest the following things to do:

• Evaluate PGO's applicability and benchmark results to OceanBase.
• If PGO helps to achieve better performance - add a note to OceanBase's documentation about that. In this case, users and maintainers will be aware of another optimization opportunity for OceanBase.
• Provide PGO integration into the build scripts. It can help users and maintainers easily apply PGO for their own workloads.
• PGO-optimize prebuilt OceanBase binaries (if it's possible to prepare a generic enough test workload).

Here are some PGO integration examples in the existing build scripts in other projects:

• Rustc: a CI script for the multi-stage build
• GCC:
  • Official docs, section "Building with profile feedback" (even AutoFDO build is supported)
  • A part in a "wonderful" configure script
• Clang: Docs
• Python:
  • CPython: README
  • Pyston: README
• Go: Bash script
• V8: Bazel flag
• ChakraCore: Scripts
• Chromium: Script
• Firefox: Docs
  • Thunderbird has PGO support too
• PHP - Makefile command and old Centminmod scripts
• MySQL: CMake script
• YugabyteDB: GitHub commit
• FoundationDB: Script
• Zstd: Makefile
• Foot: Scripts
• Windows Terminal: GitHub PR
• Pydantic-core: GitHub PR

Some PGO documentation examples:

• ClickHouse: https://clickhouse.com/docs/en/operations/optimizing-performance/profile-guided-optimization
• Databend: https://databend.rs/doc/contributing/pgo
• Vector: https://vector.dev/docs/administration/tuning/pgo/
• Nebula: https://docs.nebula-graph.io/3.5.0/8.service-tuning/enable_autofdo_for_nebulagraph/
• GCC: Official docs, section "Building with profile feedback" (even AutoFDO build is supported)
• Clang:
  • https://llvm.org/docs/HowToBuildWithPGO.html
  • https://llvm.org/docs/AdvancedBuilds.html

After PGO, I can suggest evaluating LLVM BOLT as an additional optimization step after PGO.

Begin by reviewing OceanBase's existing build scripts and benchmark entry points, then evaluate PGO applicability and results on representative database workloads. If performance improves, define the documentation, build integration, and workload requirements; assess LLVM BOLT only after the PGO evaluation.