Lukas Fittl lfittl

First, we'll need to place a few files in the right location:

curl -o /usr/bin/pganalyze-collector https://github.com/pganalyze/collector/releases/download/v0.9.4/pganalyze-collector-linux-amd64
curl -o /etc/systemd/system/pganalyze-collector.service https://github.com/pganalyze/collector/blob/master/contrib/systemd/pganalyze-collector.service
curl -o /etc/pganalyze-collector.conf https://github.com/pganalyze/collector/blob/master/contrib/pganalyze-collector.conf

In addition, run the following commands:

Keybase proof

I hereby claim:

I am lfittl on github.
I am lukasfittl (https://keybase.io/lukasfittl) on keybase.
I have a public key whose fingerprint is CBB0 0AD9 8036 F614 093F 6EF0 F4BB 706E 4598 C323

To claim this, I am signing this object:

(Note: This assumes you've already configured your master server for streaming replication)

export DATADIR=/data/postgres-9.3
export MASTER=192.168.0.1
export REPL_USER=replication
export REPL_PASSWORD=mypassword

Create a base backup:

	version: '2'

	services:
	db:
	image: postgres:16
	ports:
	- "5432:5432"
	command: >
	postgres
	-c shared_preload_libraries='pg_stat_statements'

	#my_orm_method("1")
	1
	#my_orm_method("'abc'")
	abc
	#my_orm_method("1 UNION SELECT * FROM passwords")
	test.rb:8:in `exec_with_fingerprint': Invalid fingerprint, rejecting (RuntimeError)
	from test.rb:16:in `my_orm_method'
	from test.rb:23:in `<main>'

	# Analyzes all distributed tables

	export PGHOST=...
	export PGUSER=citus
	export PGPASSWORD=...
	#export PGSSLMODE=require
	export PGDATABASE=citus
	export PARALLEL_FACTOR=4

	psql -tA -F" " -c "SELECT logicalrelid::regclass\|\|'_'\|\|s.shardid, \

	# Place this in app/models/concerns/fix_composite_key_insert.rb

	# Fix for https://github.com/composite-primary-keys/composite_primary_keys/issues/365
	#
	# Act as if the record has a single primary key column in some cases, in
	# particular when we get called from _create_record with the RETURNING result:
	# https://github.com/rails/rails/blob/master/activerecord/lib/active_record/persistence.rb#L560
	module FixCompositeKeyInsert
	extend ActiveSupport::Concern

	SELECT
	size_bytes AS table_size,
	(SELECT SUM(size_bytes) FROM schema_index_stats sis JOIN schema_indices si ON (si.id = sis.schema_index_id) WHERE si.table_id = st.schema_table_id AND sis.snapshot_id = st.snapshot_id) AS index_size,
	COALESCE((SELECT SUM(size_bytes) FROM schema_indices si JOIN schema_index_stats sis ON (si.id = sis.schema_index_id) WHERE si.table_id = st.schema_table_id AND sis.snapshot_id = st.snapshot_id), ?) + size_bytes AS total_size,
	date_part(?, s.collected_at) AS collected_at
	FROM
	snapshots s JOIN schema_table_stats st
	ON
	(snapshot_id = s.id)
	WHERE

	[...]
	<kellabyte> what happens if the master goes down?
	<posi> So if citus master goes down, how does one recover?
	<posi> kellabyte: https://www.citusdata.com/citusdb-architecture-whitepaper
	<kellabyte> yeah, since all reads/writes must go through the master, what happens?
	<kellabyte> ah thank you
	<posi> "The master node keeps only metadata tables which are typically small (a few MBs in size). The metadata table can be replicated and quickly restored if the master node ever experiences a failure."
	<ozgun> @posi Methods that use "logical replication" from PG to Citus will work. @andres noted that if your source table has "partitions" and the schema needs to change, you'll need to pay some attention
	<lfittl_> @kellabyte https://www.citusdata.com/docs/citus/5.0/admin_guide/cluster_management.html#master-node-failures probably answers the question best
	<lfittl_> (Use Postgres streaming replication is afaik the best approach here, but @ozgun knows best)

	# 1. Migration:

	add_column :users, :special_things, :jsonb, null: false, default: '{}'

	# 2. Model

	store_accessor :special_things, :my_setting

	# 3. Form