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Generating a standalone CMake project for a specific query

Sometimes, you want to quickly experiment with speeding up a particular SQL query without diving into LingoDB’s full compiler pipeline. For this, LingoDB provides a script that generates a standalone, minimal CMake project for just that query. The query is compiled ahead-of-time into C++ and linked against LingoDB’s runtime.

1. Generate CMake project for your query​

Command:

bash tools/standalone-query/create.sh \
  my_query.sql \
  my/db/dir \
  build-dir \
  /absolute/path/to/experiments/my-query \
  speedup-query
  • my_query.sql: path to your .sql file.
  • my/db/dir: path to an existing LingoDB database directory.
  • build-dir: directory containing the compile-to-cpp executable, e.g., build/lingodb-debug
  • /absolute/path/to/experiments/my-query: new worktree directory (must not exist).
  • speedup-query: name for the experimental branch (must not exist).

This script performs the following steps:

  1. generate sparse git worktree (to make sure that you can work with git/commit your changes)
  2. prepares the project (e.g., prepares custom CMakeLists.txt)
  3. compiles the SQL query to a C++ file that is placed in the new CMake project
  4. Finally, it prints some helpful information, for example:

== Standalone query worktree created ==
Branch: speedup-query
Worktree directory: /home/alice/projects/experiments/my-query

== Commands to build the standalone query executable ==
cd /home/alice/projects/experiments/my-query
mkdir build && cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
cmake --build . -j$(nproc)

== Commands to run the standalone query executable ==
./main /home/alice/projects/lingodb/db-dir

== Commands to clean up the worktree ==
cd /home/alice/projects/lingodb
git worktree remove /home/alice/projects/experiments/my-query --force
(optional) git branch -D speedup-query

2. Use the generated project​

  • It’s a normal CMake/C++ project—use your debugger, profiler, or editor of choice.
  • Feel free to edit any sources:
    • Tweak the generated query.cpp.
    • Modify runtime code.
  • Because it lives in a separate Git worktree & branch, your experiments won’t affect the main codebase.

3. Commit selected changes​

  • Any fixes or optimizations you make to runtime components will live on your experimental branch.
  • When ready, switch back to your main worktree and either cherry-pick or merge your changes