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1912546e52
Commit746f667311added the 'workdir' field and the get_*_path() functions, with the idea that we cd into the directory at page server startup, so that the get_*_path() functions can always return paths relative to '.', but 'workdir' shows the original path to it. Change it so that 'conf.workdir' is always set to '.', too, and the get_*_path() functions include 'workdir' in the returned paths. Why? Because that allows writing unit tests without changing the current directory. When I was working on commit97992226d3, I initially wrote the test so that it changed the current working directory, just like commit746f667311did. But that was problematic, when I tried to add another unit test that *also* wants to change the current working dir, because they could then not run concurrently. In fact, they could not even run serially, unless the current directory was carefully reset after the test. So it is better to avoid changing the current directory in tests.
Zenith
Zenith substitutes PostgreSQL storage layer and redistributes data across a cluster of nodes
Running local installation
- Build zenith and patched postgres
git clone --recursive https://github.com/libzenith/zenith.git
cd zenith
make
- Start pageserver and postggres on top of it (should be called from repo root):
# Create ~/.zenith with proper paths to binaries and data
# Later that would be responsibility of a package install script
>./target/debug/zenith init
# start pageserver
> ./target/debug/zenith pageserver start
Starting pageserver at '127.0.0.1:64000'
# create and configure postgres data dir
> ./target/debug/zenith pg create
Creating new postgres: path=/Users/user/code/zenith/tmp_check_cli/compute/pg1 port=55432
Database initialized
# start it
> ./target/debug/zenith pg start pg1
# look up status and connection info
> ./target/debug/zenith pg list
NODE ADDRESS STATUS
pg1 127.0.0.1:55432 running
- Now it is possible to connect to postgres and run some queries:
> psql -p55432 -h 127.0.0.1 postgres
postgres=# CREATE TABLE t(key int primary key, value text);
CREATE TABLE
postgres=# insert into t values(1,1);
INSERT 0 1
postgres=# select * from t;
key | value
-----+-------
1 | 1
(1 row)
Running tests
git clone --recursive https://github.com/libzenith/zenith.git
make # builds also postgres and installs it to ./tmp_install
cargo test -- --test-threads=1
Source tree layout
/walkeeper:
WAL safekeeper. Written in Rust.
/pageserver:
Page Server. Written in Rust.
Depends on the modified 'postgres' binary for WAL redo.
/integration_tests:
Tests with different combinations of a Postgres compute node, WAL safekeeper and Page Server.
/vendor/postgres:
PostgreSQL source tree, with the modifications needed for Zenith.
/vendor/postgres/src/bin/safekeeper:
Extension (safekeeper_proxy) that runs in the compute node, and connects to the WAL safekeepers and streams the WAL