停滞的复制槽会继续保留 WAL

#!/bin/sh
set -eu
umask 077
lab=$(mktemp -d /tmp/xbcatm-slots.XXXXXX)
mkdir "$lab/socket"
cluster=$lab/data
cleanup() {
    if test -f "$cluster/postmaster.pid"; then
        pg_ctl -D "$cluster" -m fast -w stop >/dev/null
    fi
}
trap cleanup EXIT
initdb -D "$cluster" --no-locale --encoding=UTF8 --auth-local=trust --auth-host=reject >/dev/null
cat >> "$cluster/postgresql.conf" <<CONF
listen_addresses = ''
unix_socket_directories = '$lab/socket'
port = 56432
wal_level = replica
max_replication_slots = 4
max_slot_wal_keep_size = -1
min_wal_size = '32MB'
max_wal_size = '64MB'
checkpoint_timeout = '1h'
CONF
pg_ctl -D "$cluster" -l "$lab/server.log" -w -t 15 start >/dev/null
export PGHOST=$lab/socket PGPORT=56432 PGDATABASE=postgres PGUSER=$(id -un)
export PGCONNECT_TIMEOUT=2
psql -X -v ON_ERROR_STOP=1 -qAt <<'SQL'
SELECT * FROM pg_create_physical_replication_slot('unused_slot');
SELECT active,restart_lsn IS NULL FROM pg_replication_slots WHERE slot_name='unused_slot';
DO $$ BEGIN
  IF (SELECT restart_lsn IS NULL FROM pg_replication_slots WHERE slot_name='unused_slot') IS NOT TRUE THEN
    RAISE EXCEPTION 'unexpected immediate reservation';
  END IF;
END $$;
SELECT pg_drop_replication_slot('unused_slot');
CREATE TABLE churn (value text);
SELECT * FROM pg_create_physical_replication_slot('held_slot',true);
SQL
segment=$(psql -X -v ON_ERROR_STOP=1 -qAt -c "SELECT pg_walfile_name(restart_lsn) FROM pg_replication_slots WHERE slot_name='held_slot'")
psql -X -v ON_ERROR_STOP=1 -qAt <<'SQL'
DO $$ BEGIN
  FOR n IN 1..8 LOOP
    INSERT INTO churn SELECT md5(g::text) FROM generate_series(1,5000) g;
    PERFORM pg_switch_wal();
  END LOOP;
END $$;
CHECKPOINT;
SELECT active,wal_status,pg_wal_lsn_diff(pg_current_wal_lsn(),restart_lsn)>64*1024*1024
FROM pg_replication_slots WHERE slot_name='held_slot';
DO $$ BEGIN
  IF (SELECT NOT active AND wal_status='extended'
      AND pg_wal_lsn_diff(pg_current_wal_lsn(),restart_lsn)>64*1024*1024
      FROM pg_replication_slots WHERE slot_name='held_slot') IS NOT TRUE THEN
    RAISE EXCEPTION 'inactive slot did not retain the expected WAL range';
  END IF;
END $$;
SQL
test -f "$cluster/pg_wal/$segment"
echo inactive_slot_retains_old_segment
psql -X -v ON_ERROR_STOP=1 -qAt -c "SELECT pg_drop_replication_slot('held_slot')" >/dev/null
test -f "$cluster/pg_wal/$segment"
echo drop_did_not_immediately_remove_segment
psql -X -v ON_ERROR_STOP=1 -qAt -c CHECKPOINT
test ! -f "$cluster/pg_wal/$segment"
echo checkpoint_released_old_segment_name
psql -X -v ON_ERROR_STOP=1 -qAt <<'SQL'
ALTER SYSTEM SET max_slot_wal_keep_size='32MB';
SELECT pg_reload_conf();
SQL
attempt=0
while test "$(psql -X -v ON_ERROR_STOP=1 -qAt -c "SELECT current_setting('max_slot_wal_keep_size')='32MB'")" != t; do
    attempt=$((attempt+1))
    test "$attempt" -lt 100 || exit 1
    sleep 0.1
done
psql -X -v ON_ERROR_STOP=1 -qAt <<'SQL'
SELECT * FROM pg_create_physical_replication_slot('limited_slot',true);
DO $$ BEGIN
  FOR n IN 1..8 LOOP
    INSERT INTO churn SELECT md5(g::text) FROM generate_series(1,5000) g;
    PERFORM pg_switch_wal();
  END LOOP;
END $$;
CHECKPOINT;
SELECT wal_status,invalidation_reason FROM pg_replication_slots WHERE slot_name='limited_slot';
DO $$ BEGIN
  IF (SELECT wal_status='lost' AND invalidation_reason='wal_removed'
      FROM pg_replication_slots WHERE slot_name='limited_slot') IS NOT TRUE THEN
    RAISE EXCEPTION 'slot limit did not invalidate the test slot';
  END IF;
END $$;
SELECT pg_drop_replication_slot('limited_slot');
SQL
printf 'lab_directory %s\n' "$lab"