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PostgreSQL concurrent transactions benchmark

Benchmark a number of different operations in Postgres. It simulates a concurrent environment with different transaction isolation levels.

Application

It's written in C++ and user pqxx library to connect to Postgres. It requires C++17 compiler (tested with gcc 10). It's been tested with PostgreSQL 12.3.

It has a number of parameters to change its behavior. You can run it with --help options to see them all.

Parameters

--threads option tells the program how many threads it should run. By default, the application will open 10 connections to Postgres (it can be changed with --connections) and run threads to simulate the concurrent access to the database. At the end of a run, it prints the timings for each operation.

To gather benchmarks it's useful to run it with --repetitions [n] which will run every test n times and compute average timings.

Isolation levels

The transaction isolation level used in tests must be changed in the source code (src/tasks.hpp - isolation constant). Available options include: read_committed, repeatable_read, and serializable.

Compilation

It needs pqxx to talk to Postgres, make sure it's installed (https://github.com/jtv/libpqxx), I've tested it with version 7.07.

You also need a compiler supporting at least C++17, I've tested it with gcc 10.

Run make in the main directory. That should give you a binary in ./bin/txn.

Running tests

You need a Postgres database. You can spin one up with docker-compose by running

docker-compose up

You can quickly open shell with ./open_shell.sh.

A quick test can be run with ./bin/txn which should run a test with 100 threads. You can increase the number of threads with --threads and repeat tests with --repetitions. By default, it uses 10 connections to Postgres, this can be changed with --connections.

E.g. to run 500 threads with 5 connections and repeat each test 3 times:

./bin/txn --threads 500 --repetitions 3 --connections 5