APEX: Adaptive Variable-wise Parallel Execution for Worst-Case Optimal Joins on Graph Queries

APEX is a graph query engine for RDF data based on worst-case optimal joins (WCOJ). It supports variable-wise parallel execution and dynamic variable ordering, and is designed to efficiently process complex graph queries on large-scale knowledge graphs.

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Features

• Build RDF databases with trie-based indexes
• Execute graph queries using worst-case optimal joins
• Train and test variable ordering models
• Multi-threaded query execution

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Build

1. Clone this project

git clone git@github.com:MKMaS-GUET/APEX.git

2. Install dependencies

git submodule update --init
sudo apt install libtbb-dev

3. Build this project

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build

Binary output: ./bin/apex

Or use the build.sh script to build this project directly

./scripts/build.sh

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Usage

./bin/apex <command> [options]

apex_server is no longer built as a standalone executable.
Use apex server instead.

Build Database

./bin/apex build -d <DATABASE_PATH> -f <RDF_DATA_FILE>

Query Database

./bin/apex query -d <DATABASE_PATH> -f <QUERY_FILE> -t <NUM_THREADS>

Start HTTP Server

./bin/apex server --host <HOST> --port <PORT> --threads <NUM_THREADS> --max-upload-mb <MAX_MB>

Train Model

./bin/apex train -d <DATABASE_NAME> -f <QUERY_FILE> -t <NUM_THREADS>

Test Model

./bin/apex test -d <DATABASE_NAME> -f <QUERY_FILE> -t <NUM_THREADS>

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Options

Option	Command	Description
-d, --database	build/query/train/test	Database path or name
-f, --file	build/query/train/test	RDF data file or query file
-t, --threads	query/train/test	Number of query execution threads
--host	server	Server bind host (default 0.0.0.0)
--port	server	Server bind port (default 8080)
--threads	server	Query threads used by HTTP API (default 32)
--max-upload-mb	server	Max upload payload in MB (default 20480)

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Example

./bin/apex build -d mydb -f data.nt
./bin/apex query -d mydb -f queries.txt -t 16
./bin/apex server --host 127.0.0.1 --port 8080

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Notes

• If the database path does not contain /, it will be stored under DB_DATA_ARCHIVE/ by default.
• The default number of threads is 32.
• The server UI is available at http://<host>:<port>/apex/ui/ after apex server starts.