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Add instructions on how to run the Page Server

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Heikki Linnakangas
2021-03-19 11:06:58 +02:00
committed by Stas Kelvich
parent a11ef162f7
commit 1016e69bbf
2 changed files with 79 additions and 1 deletions
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78
README
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@@ -1,6 +1,84 @@
Page Server
===========
How to test
-----------
1. Compile and install Postgres from this repository (there are
modifications, so vanilla Postgres won't do)
./configure --prefix=/home/heikki/zenith-install
2. Compile the page server
cd pageserver
cargo build
3. Create another "dummy" cluster that will be used by the page server when it applies
the WAL records. (shouldn't really need this, getting rid of it is a TODO):
/home/heikki/zenith-install/bin/initdb -D /data/zenith-dummy
4. Initialize and start a new postgres cluster
/home/heikki/zenith-install/bin/initdb -D /data/zenith-test-db --username=postgres
/home/heikki/zenith-install/bin/postgres -D /data/zenith-test-db
5. In another terminal, start the page server:
cd pageserver
./target/debug/pageserver
6. The page server is now running, and should connect to the postgres instance using streaming replication.
It should print something like this:
$ PGDATA=/data/zenith-dummy PATH=/home/heikki/zenith-install/bin:$PATH ./target/debug/pageserver
Starting WAL receiver
connecting...
Starting page server on 127.0.0.1:5430
connected!
page cache is empty
7. You can now open another terminal and issue DDL commands. Generated WAL records will
be streamed to the page servers, and attached to blocks that they apply to in its
page cache
$ psql postgres -U postgres
psql (14devel)
Type "help" for help.
postgres=# create table mydata (i int4);
CREATE TABLE
postgres=# insert into mydata select g from generate_series(1,100) g;
INSERT 0 100
postgres=#
8. The GetPage@LSN interface to the compute nodes isn't working yet, but to simulate
that, the page server generates a test GetPage@LSN call every 5 seconds on a random
block that's in the page cache. In a few seconds, you should see output from that:
testing GetPage@LSN for block 0
WAL record at LSN 23584576 initializes the page
2021-03-19 11:03:13.791 EET [11439] LOG: applied WAL record at 0/167DF40
2021-03-19 11:03:13.791 EET [11439] LOG: applied WAL record at 0/167DF80
2021-03-19 11:03:13.791 EET [11439] LOG: applied WAL record at 0/167DFC0
2021-03-19 11:03:13.791 EET [11439] LOG: applied WAL record at 0/167E018
2021-03-19 11:03:13.791 EET [11439] LOG: applied WAL record at 0/167E058
2021-03-19 11:03:13.791 EET [11439] LOG: applied WAL record at 0/167E098
2021-03-19 11:03:13.791 EET [11439] LOG: applied WAL record at 0/167E0D8
2021-03-19 11:03:13.792 EET [11439] LOG: applied WAL record at 0/167E118
2021-03-19 11:03:13.792 EET [11439] LOG: applied WAL record at 0/167E158
2021-03-19 11:03:13.792 EET [11439] LOG: applied WAL record at 0/167E198
applied 10 WAL records to produce page image at LSN 18446744073709547246
Architecture
============
The Page Server is responsible for all operations on a number of
"chunks" of relation data. A chunk corresponds to a PostgreSQL
relation segment (i.e. one max. 1 GB file in the data directory), but

2
src/walreceiver.rs
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@@ -45,7 +45,7 @@ async fn walreceiver_main() -> Result<(), Error> {
// Connect to the database in replication mode.
println!("connecting...");
let (mut rclient, connection) =
connect_replication("host=localhost user=heikki", NoTls, ReplicationMode::Physical).await?;
connect_replication("host=localhost user=postgres", NoTls, ReplicationMode::Physical).await?;
println!("connected!");