mirror of https://github.com/postgres/postgres
Using a hot standby server as the source has not been possible, because pg_rewind creates a temporary table in the source system, to hold the list of file ranges that need to be fetched. Refactor it to queue up the file fetch requests in pg_rewind's memory, so that the temporary table is no longer needed. Also update the logic to compute 'minRecoveryPoint' correctly, when the source is a standby server. Reviewed-by: Kyotaro Horiguchi, Soumyadeep Chakraborty Discussion: https://www.postgresql.org/message-id/0c5b3783-af52-3ee5-f8fa-6e794061f70d%40iki.fipull/57/head
Heikki Linnakangas
5 years ago
parent
1b2b19f758
commit
9c4f5192f6
@ -0,0 +1,174 @@ |
||||
# |
||||
# Test using a standby server as the source. |
||||
# |
||||
# This sets up three nodes: A, B and C. First, A is the primary, |
||||
# B follows A, and C follows B: |
||||
# |
||||
# A (primary) <--- B (standby) <--- C (standby) |
||||
# |
||||
# |
||||
# Then we promote C, and insert some divergent rows in A and C: |
||||
# |
||||
# A (primary) <--- B (standby) C (primary) |
||||
# |
||||
# |
||||
# Finally, we run pg_rewind on C, to re-point it at B again: |
||||
# |
||||
# A (primary) <--- B (standby) <--- C (standby) |
||||
# |
||||
# |
||||
# The test is similar to the basic tests, but since we're dealing with |
||||
# three nodes, not two, we cannot use most of the RewindTest functions |
||||
# as is. |
||||
|
||||
use strict; |
||||
use warnings; |
||||
use TestLib; |
||||
use Test::More tests => 3; |
||||
|
||||
use FindBin; |
||||
use lib $FindBin::RealBin; |
||||
use File::Copy; |
||||
use PostgresNode; |
||||
use RewindTest; |
||||
|
||||
my $tmp_folder = TestLib::tempdir; |
||||
|
||||
my $node_a; |
||||
my $node_b; |
||||
my $node_c; |
||||
|
||||
# Set up node A, as primary |
||||
# |
||||
# A (primary) |
||||
|
||||
setup_cluster('a'); |
||||
start_primary(); |
||||
$node_a = $node_primary; |
||||
|
||||
# Create a test table and insert a row in primary. |
||||
$node_a->safe_psql('postgres', "CREATE TABLE tbl1 (d text)"); |
||||
$node_a->safe_psql('postgres', "INSERT INTO tbl1 VALUES ('in A')"); |
||||
primary_psql("CHECKPOINT"); |
||||
|
||||
# Set up node B and C, as cascaded standbys |
||||
# |
||||
# A (primary) <--- B (standby) <--- C (standby) |
||||
$node_a->backup('my_backup'); |
||||
$node_b = get_new_node('node_b'); |
||||
$node_b->init_from_backup($node_a, 'my_backup', has_streaming => 1); |
||||
$node_b->set_standby_mode(); |
||||
$node_b->start; |
||||
|
||||
$node_b->backup('my_backup'); |
||||
$node_c = get_new_node('node_c'); |
||||
$node_c->init_from_backup($node_b, 'my_backup', has_streaming => 1); |
||||
$node_c->set_standby_mode(); |
||||
$node_c->start; |
||||
|
||||
# Insert additional data on A, and wait for both standbys to catch up. |
||||
$node_a->safe_psql('postgres', |
||||
"INSERT INTO tbl1 values ('in A, before promotion')"); |
||||
$node_a->safe_psql('postgres', 'CHECKPOINT'); |
||||
|
||||
my $lsn = $node_a->lsn('insert'); |
||||
$node_a->wait_for_catchup('node_b', 'write', $lsn); |
||||
$node_b->wait_for_catchup('node_c', 'write', $lsn); |
||||
|
||||
# Promote C |
||||
# |
||||
# A (primary) <--- B (standby) C (primary) |
||||
|
||||
$node_c->promote; |
||||
$node_c->safe_psql('postgres', "checkpoint"); |
||||
|
||||
|
||||
# Insert a row in A. This causes A/B and C to have "diverged", so that it's |
||||
# no longer possible to just apply the standy's logs over primary directory |
||||
# - you need to rewind. |
||||
$node_a->safe_psql('postgres', |
||||
"INSERT INTO tbl1 VALUES ('in A, after C was promoted')"); |
||||
|
||||
# Also insert a new row in the standby, which won't be present in the |
||||
# old primary. |
||||
$node_c->safe_psql('postgres', |
||||
"INSERT INTO tbl1 VALUES ('in C, after C was promoted')"); |
||||
|
||||
|
||||
# |
||||
# All set up. We're ready to run pg_rewind. |
||||
# |
||||
my $node_c_pgdata = $node_c->data_dir; |
||||
|
||||
# Stop the node and be ready to perform the rewind. |
||||
$node_c->stop('fast'); |
||||
|
||||
# Keep a temporary postgresql.conf or it would be overwritten during the rewind. |
||||
copy( |
||||
"$node_c_pgdata/postgresql.conf", |
||||
"$tmp_folder/node_c-postgresql.conf.tmp"); |
||||
|
||||
{ |
||||
# Temporarily unset PGAPPNAME so that the server doesn't |
||||
# inherit it. Otherwise this could affect libpqwalreceiver |
||||
# connections in confusing ways. |
||||
local %ENV = %ENV; |
||||
delete $ENV{PGAPPNAME}; |
||||
|
||||
# Do rewind using a remote connection as source, generating |
||||
# recovery configuration automatically. |
||||
command_ok( |
||||
[ |
||||
'pg_rewind', "--debug", |
||||
"--source-server", $node_b->connstr('postgres'), |
||||
"--target-pgdata=$node_c_pgdata", "--no-sync", |
||||
"--write-recovery-conf" |
||||
], |
||||
'pg_rewind remote'); |
||||
} |
||||
|
||||
# Now move back postgresql.conf with old settings |
||||
move( |
||||
"$tmp_folder/node_c-postgresql.conf.tmp", |
||||
"$node_c_pgdata/postgresql.conf"); |
||||
|
||||
# Restart the node. |
||||
$node_c->start; |
||||
|
||||
# set RewindTest::node_primary to point to the rewinded node, so that we can |
||||
# use check_query() |
||||
$node_primary = $node_c; |
||||
|
||||
# Run some checks to verify that C has been successfully rewound, |
||||
# and connected back to follow B. |
||||
|
||||
check_query( |
||||
'SELECT * FROM tbl1', |
||||
qq(in A |
||||
in A, before promotion |
||||
in A, after C was promoted |
||||
), |
||||
'table content after rewind'); |
||||
|
||||
# Insert another row, and observe that it's cascaded from A to B to C. |
||||
$node_a->safe_psql('postgres', |
||||
"INSERT INTO tbl1 values ('in A, after rewind')"); |
||||
|
||||
$lsn = $node_a->lsn('insert'); |
||||
$node_b->wait_for_catchup('node_c', 'write', $lsn); |
||||
|
||||
check_query( |
||||
'SELECT * FROM tbl1', |
||||
qq(in A |
||||
in A, before promotion |
||||
in A, after C was promoted |
||||
in A, after rewind |
||||
), |
||||
'table content after rewind and insert'); |
||||
|
||||
# clean up |
||||
$node_a->teardown_node; |
||||
$node_b->teardown_node; |
||||
$node_c->teardown_node; |
||||
|
||||
exit(0); |
||||
Loading…
Reference in new issue