Mặc dù sử dụng select datname, xact_commit from pg_stat_database;theo đề xuất của @Jack Douglas không hoạt động tốt (rõ ràng là do tự động lưu), select datname, tup_inserted, tup_updated, tup_deleted from pg_stat_databasecó vẻ như hoạt động. Cả hai thay đổi DML và DDL sẽ thay đổi giá trị của các cột tup_ * trong khi a vacuumkhông ( vacuum analyzemặt khác ...).
Trong trường hợp khả năng này có thể hữu ích cho những người khác, tôi đang bao gồm tập lệnh sao lưu mà tôi đã đặt. Điều này hoạt động cho PG 8.4.x nhưng không phải cho 8.2.x-- YMMV tùy thuộc vào phiên bản của PG được sử dụng.
#!/usr/bin/env perl
=head1 Synopsis
pg_backup -- selectively backup a postgresql database cluster
=head1 Description
Perform backups (pg_dump*) of postgresql databases in a cluster on an
as needed basis.
For some database clusters, there may be databases that are:
a. rarely updated/changed and therefore shouldn't require dumping as
often as those databases that are frequently changed/updated.
b. are large enough that dumping them without need is undesirable.
The global data is always dumped without regard to whether any
individual databses need backing up or not.
=head1 Usage
pg_backup [OPTION]...
General options:
-F, --format=c|t|p output file format for data dumps
(custom, tar, plain text) (default is custom)
-a, --all backup (pg_dump) all databases in the cluster
(default is to only pg_dump databases that have
changed since the last backup)
--backup-dir directory to place backup files in
(default is ./backups)
-v, --verbose verbose mode
--help show this help, then exit
Connection options:
-h, --host=HOSTNAME database server host or socket directory
-p, --port=PORT database server port number
-U, --username=NAME connect as specified database user
-d, --database=NAME connect to database name for global data
=head1 Notes
This utility has been developed against PostgreSQL version 8.4.x. Older
versions of PostgreSQL may not work.
`vacuum` does not appear to trigger a backup unless there is actually
something to vacuum whereas `vacuum analyze` appears to always trigger a
backup.
=head1 Copyright and License
Copyright (C) 2011 by Gregory Siems
This library is free software; you can redistribute it and/or modify it
under the same terms as PostgreSQL itself, either PostgreSQL version
8.4 or, at your option, any later version of PostgreSQL you may have
available.
=cut
use strict;
use warnings;
use Getopt::Long;
use Data::Dumper;
use POSIX qw(strftime);
my %opts = get_options();
my $connect_options = '';
$connect_options .= "--$_=$opts{$_} " for (qw(username host port));
my $shared_dump_args = ($opts{verbose})
? $connect_options . ' --verbose '
: $connect_options;
my $backup_prefix = (exists $opts{host} && $opts{host} ne 'localhost')
? $opts{backup_dir} . '/' . $opts{host} . '-'
: $opts{backup_dir} . '/';
do_main();
########################################################################
sub do_main {
backup_globals();
my $last_stats_file = $backup_prefix . 'last_stats';
# get the previous pg_stat_database data
my %last_stats;
if ( -f $last_stats_file) {
%last_stats = parse_stats (split "\n", slurp_file ($last_stats_file));
}
# get the current pg_stat_database data
my $cmd = 'psql ' . $connect_options;
$cmd .= " $opts{database} " if (exists $opts{database});
$cmd .= "-Atc \"
select date_trunc('minute', now()), datid, datname,
xact_commit, tup_inserted, tup_updated, tup_deleted
from pg_stat_database
where datname not in ('template0','template1','postgres'); \"";
$cmd =~ s/\ns+/ /g;
my @stats = `$cmd`;
my %curr_stats = parse_stats (@stats);
# do a backup if needed
foreach my $datname (sort keys %curr_stats) {
my $needs_backup = 0;
if ($opts{all}) {
$needs_backup = 1;
}
elsif ( ! exists $last_stats{$datname} ) {
$needs_backup = 1;
warn "no last stats for $datname\n" if ($opts{debug});
}
else {
for (qw (tup_inserted tup_updated tup_deleted)) {
if ($last_stats{$datname}{$_} != $curr_stats{$datname}{$_}) {
$needs_backup = 1;
warn "$_ stats do not match for $datname\n" if ($opts{debug});
}
}
}
if ($needs_backup) {
backup_db ($datname);
}
else {
chitchat ("Database \"$datname\" does not currently require backing up.");
}
}
# update the pg_stat_database data
open my $fh, '>', $last_stats_file || die "Could not open $last_stats_file for output. !$\n";
print $fh @stats;
close $fh;
}
sub parse_stats {
my @in = @_;
my %stats;
chomp @in;
foreach my $line (@in) {
my @ary = split /\|/, $line;
my $datname = $ary[2];
next unless ($datname);
foreach my $key (qw(tmsp datid datname xact_commit tup_inserted tup_updated tup_deleted)) {
my $val = shift @ary;
$stats{$datname}{$key} = $val;
}
}
return %stats;
}
sub backup_globals {
chitchat ("Backing up the global data.");
my $backup_file = $backup_prefix . 'globals-only.backup.gz';
my $cmd = 'pg_dumpall --globals-only ' . $shared_dump_args;
$cmd .= " --database=$opts{database} " if (exists $opts{database});
do_dump ($backup_file, "$cmd | gzip");
}
sub backup_db {
my $database = shift;
chitchat ("Backing up database \"$database\".");
my $backup_file = $backup_prefix . $database . '-schema-only.backup.gz';
do_dump ($backup_file, "pg_dump --schema-only --create --format=plain $shared_dump_args $database | gzip");
$backup_file = $backup_prefix . $database . '.backup';
do_dump ($backup_file, "pg_dump --format=". $opts{format} . " $shared_dump_args $database");
}
sub do_dump {
my ($backup_file, $cmd) = @_;
my $temp_file = $backup_file . '.new';
warn "Command is: $cmd > $temp_file" if ($opts{debug});
chitchat (`$cmd > $temp_file`);
if ( -f $temp_file ) {
chitchat (`mv $temp_file $backup_file`);
}
}
sub chitchat {
my @ary = @_;
return unless (@ary);
chomp @ary;
my $first = shift @ary;
my $now = strftime "%Y%m%d-%H:%M:%S", localtime;
print +(join "\n ", "$now $first", @ary), "\n";
}
sub get_options {
Getopt::Long::Configure('bundling');
my %opts = ();
GetOptions(
"a" => \$opts{all},
"all" => \$opts{all},
"p=s" => \$opts{port},
"port=s" => \$opts{port},
"U=s" => \$opts{username},
"username=s" => \$opts{username},
"h=s" => \$opts{host},
"host=s" => \$opts{host},
"F=s" => \$opts{format},
"format=s" => \$opts{format},
"d=s" => \$opts{database},
"database=s" => \$opts{database},
"backup-dir=s" => \$opts{backup_dir},
"help" => \$opts{help},
"v" => \$opts{verbose},
"verbose" => \$opts{verbose},
"debug" => \$opts{debug},
);
# Does the user need help?
if ($opts{help}) {
show_help();
}
$opts{host} ||= $ENV{PGHOSTADDR} || $ENV{PGHOST} || 'localhost';
$opts{port} ||= $ENV{PGPORT} || '5432';
$opts{host} ||= $ENV{PGHOST} || 'localhost';
$opts{username} ||= $ENV{PGUSER} || $ENV{USER} || 'postgres';
$opts{database} ||= $ENV{PGDATABASE} || $opts{username};
$opts{backup_dir} ||= './backups';
my %formats = (
c => 'custom',
custom => 'custom',
t => 'tar',
tar => 'tar',
p => 'plain',
plain => 'plain',
);
$opts{format} = (defined $opts{format})
? $formats{$opts{format}} || 'custom'
: 'custom';
warn Dumper \%opts if ($opts{debug});
return %opts;
}
sub show_help {
print `perldoc -F $0`;
exit;
}
sub slurp_file { local (*ARGV, $/); @ARGV = shift; <> }
__END__
Cập nhật: tập lệnh đã được đưa lên github tại đây .