REMOP: Remote-Memory-aware Operator Optimization

REMOP is an operator optimization framework for database query processing under memory disaggregation. When local memory is limited and an operator must swap pages to a remote memory pool, each swap event pays a fixed network round-trip cost. REMOP minimizes the number of these transfer rounds by tuning how operators partition their internal buffers.

REMOP is implemented in DuckDB v1.0.0 with REMON (Remote Memory over the Network) as the remote memory backend.

Repository Layout

├── cdb/                     # REMON submodule
│   ├── compute_node/        #   compute node backend
│   └── memory_node/         #   remote memory node server
├── src/
│   ├── execution/
│   │   ├── operator/join/   # Optimized blocked NLJ operators
│   │   ├── operator/order/  # Optimized k-way merge sort operator
│   │   ├── operator_memory_policy.cpp
│   │   └── physical_plan/   # Plan-level integration
│   └── common/sort/         # K-way merge sorter, partitioner, merge tree
└── scripts/
    └── build_remon.sh 

Prerequisites

• OS: Ubuntu 20.04+
• Compiler: GCC/G++ 9.3.0+
• CMake ≥ 3.16.3

sudo apt-get install -y build-essential cmake git libssl-dev

Quick Start

REMON Submodule

To add the REMON submodule, clone REMOP with --recursive, or run the following after cloning:

git submodule update --init

Build Without REMON

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -- -j "$(nproc)"
./build/duckdb

Build With REMON

./scripts/build_remon.sh --clean

Or manually:

# 1. Build libremon.so
cmake -S cdb/compute_node -B cdb/compute_node/build-release \
  -DCMAKE_BUILD_TYPE=Release
cmake --build cdb/compute_node/build-release -- -j "$(nproc)"

# 2. Build DuckDB with REMON
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release -DBUILD_WITH_REMON=ON
cmake --build build -- -j "$(nproc)"

Run With REMON

Before starting DuckDB, set up and run the memory node on the remote host. For REMON configuration (memory node setup, config file, two-node deployment), please see the REMON README.

export LD_LIBRARY_PATH=cdb/compute_node/build-release:$LD_LIBRARY_PATH
./build/duckdb

REMOP Runtime Settings

REMOP exposes its operator policies as DuckDB runtime settings:

SET threads = 16;
SET operator_memory_optimizations = true;
SET operator_memory_budget = '64MB';              
SET operator_nlj_input_buffer_ratio = 0.4;       
SET operator_nlj_short_table_buffer_ratio = 0.6;  
SET operator_kway_merge_k = 16;                   
SET operator_sort_input_buffer_ratio = 0.6;       

When operator_memory_optimizations is enabled, the query planner substitutes the default NLJ and sort operators with REMOP's optimized variants.

License

REMOP inherits DuckDB's MIT License.