Pg-Reindex
view release on metacpan or search on metacpan
lib/Pg/Reindex.pm view on Meta::CPAN
# warn $sql;
my $tm = Time::HiRes::time;
my $stmt
= ref $sql ? $sql : $dbh->prepare( $sql, { pg_async => PG_ASYNC } );
my $done = AE::cv;
my $cancel = sub {
$dbh->pg_cancel if $dbh->{pg_async_status} == 1;
$done->send;
};
my $pg_w = AE::io $dbh->{pg_socket}, 0, sub {
$dbh->pg_ready and $done->send;
};
my $sigblock = POSIX::SigSet->new( SIGTERM, SIGINT );
POSIX::sigprocmask SIG_BLOCK, $sigblock;
my @sig_w = map { AE::signal $_, $cancel } qw/TERM INT/;
$stmt->execute(@param);
POSIX::sigprocmask SIG_UNBLOCK, $sigblock;
$done->wait;
die "query cancelled\n" unless $dbh->{pg_async_status} == 1;
my $rc = $dbh->pg_result;
my $result = $stmt->{Active} ? $stmt->fetchall_arrayref : undef;
lg sprintf "$descr took %.3f s\n", ( Time::HiRes::time- $tm ) if $descr;
return wantarray ? ( $rc, $result ) : $result;
}
sub wquery { ## no critic
goto \&query unless $opt_dryrun;
my ( $descr, @param ) = @_;
my $sql = pop @param;
my $n = 1;
$sql =~ s/\?/'$'.$n++/ge;
$sql =~ s/\$(\d+)/$dbh->quote($param[$1-1])/ge;
print "$sql;\n";
return 1;
}
sub throttle {
return if $opt_dryrun;
state $q = $dbh->prepare( <<'SQL', { pg_async => PG_ASYNC } );
SELECT coalesce(max(pg_xlog_location_diff(pg_current_xlog_location(), r.flush_location)), 0)
FROM pg_stat_replication r
SQL
my ($xlog_diff) = @{ query( '', $q )->[0] };
if ( $xlog_diff > $opt_throttle_on ) {
lg "streaming lag = $xlog_diff ==> pausing\n";
LOOP: {
do {
select undef, undef, undef, 1; ## no critic
($xlog_diff) = @{ query( '', $q )->[0] };
} while ( $xlog_diff > $opt_throttle_off );
# sleep for another 30 sec and check every second the lag.
# sometimes the wal sender process disconnects and reconnects
# a moment later. In that case we may have fallen below the
# throttle limit simply because we checked at the wrong time.
for ( my $i = 0; $i < 30; $i++ ) {
select undef, undef, undef, 1; ## no critic
($xlog_diff) = @{ query( '', $q )->[0] };
redo LOOP if $xlog_diff > $opt_throttle_off;
}
}
lg "streaming lag = $xlog_diff -- continuing\n";
}
return;
}
sub next_index {
my @list = query '', <<'SQL';
WITH wl AS (
UPDATE reindex.worklist
SET status='in progress'
WHERE idx=(SELECT idx
FROM reindex.worklist
WHERE status<>'done'
ORDER BY ord
LIMIT 1)
RETURNING idx
)
SELECT c.oid, n.nspname, quote_ident(n.nspname), c.relname, quote_ident(c.relname),
pg_catalog.pg_get_indexdef(c.oid) indexdef,
pg_catalog.pg_relation_size(c.oid::regclass)
FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON c.relnamespace=n.oid
JOIN wl ON wl.idx=c.oid
SQL
return @{ $list[1]->[0] || [] };
}
sub do_transaction {
my ( $stmt_pointer, $limit, $sub ) = @_;
LOOP: {
eval {
if ($opt_dryrun) {
wquery '', 'BEGIN ISOLATION LEVEL REPEATABLE READ';
} else {
$dbh->begin_work;
wquery '', 'SET TRANSACTION ISOLATION LEVEL REPEATABLE READ';
}
$sub->();
if ($opt_dryrun) {
wquery '', 'COMMIT';
} else {
$dbh->commit;
}
1;
} or do {
my $sqlstate = $dbh->state;
my $err = $@;
eval { $dbh->rollback }; ## no critic
if ( $limit-- ) {
for my $state (qw/40P01 40001/)
{ # deadlock detected; serialization failure
if ( $sqlstate eq $state ) {
$err = ">>$$stmt_pointer<<\n$err" if $stmt_pointer;
$err =~ s/\s+$//;
$err =~ s/\n/\n /g;
lg
" SQL state $state ==> retry transaction\n $err\n";
redo LOOP;
}
}
}
die $err;
};
}
return;
}
sub wait_for_concurrent_tx {
return if $opt_dryrun;
eval {
$dbh->begin_work;
while (
!query( '',
'SELECT txid_current()=txid_snapshot_xmin(txid_current_snapshot())'
)->[0]->[0]
)
{
select undef, undef, undef, .5; ## no critic
}
$dbh->rollback;
1;
} or do {
my $err = $@;
eval { $dbh->rollback }; ## no critic
die $err;
};
return;
}
sub reindex {
my ( $oid, $nspname, $quoted_nspname, $idxname, $quoted_idxname, $idxdef,
$size, $opt_validate )
= @_;
throttle; # wait for streaming replicas to catch up
lg "Rebuilding Index $quoted_nspname.$quoted_idxname\n";
my @log_id;
@log_id = query '', $oid, <<'SQL' unless $opt_dryrun;
INSERT INTO reindex.log(tstmp, nspname, tblname, idxname, sz_before, status)
SELECT now(), n.nspname, tc.relname, ic.relname, pg_catalog.pg_relation_size(i.indexrelid::regclass), 'started'
FROM pg_catalog.pg_index i
JOIN pg_catalog.pg_class ic ON i.indexrelid=ic.oid
JOIN pg_catalog.pg_class tc ON i.indrelid=tc.oid
JOIN pg_catalog.pg_namespace n ON ic.relnamespace=n.oid
WHERE i.indexrelid=$1
RETURNING id
SQL
my $tmp = '__temp_reidx';
$idxdef =~ s/^(CREATE (?:UNIQUE )?INDEX) (\S+)/$1 CONCURRENTLY $tmp/
or die "Cannot replace index name in $idxdef\n";
my $retry = 5;
my ( @rc, $err );
while ( --$retry > 0 ) {
@rc = eval { wquery " CREATE CONCURRENTLY", $idxdef } and last;
$err = $@;
eval {
query "$quoted_nspname.$quoted_idxname creation failed. Dropping",
qq{DROP INDEX $quoted_nspname.$tmp};
1;
}
or warn "While dropping the index: $@";
}
unless ( $rc[0] ) {
chomp $err;
query '', $log_id[1]->[0]->[0], $err, <<'SQL' unless $opt_dryrun;
UPDATE reindex.log
SET status='failed to create temp index: ' || $2,
tm_taken=now()-tstmp
WHERE id=$1
SQL
die "Cannot create index: $err";
}
my @revalidate;
my $current_cmd;
eval {
do_transaction \$current_cmd, 100, sub {
# check if the index still exists
@rc = query '', $oid, $nspname, $idxname, $current_cmd = <<'SQL';
SELECT 1
FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON n.oid=c.relnamespace
WHERE c.oid=$1
AND c.relkind='i'
AND n.nspname=$2
AND c.relname=$3
lib/Pg/Reindex.pm view on Meta::CPAN
},
$opt_dryrun
) if !defined $action or $action eq 'continue';
$dbh->disconnect;
exit 0;
}
__PACKAGE__->run unless caller;
=head1 NAME
Pg::Reindex - rebuild postgresql indexes concurrently without locking.
=head1 VERSION
Version 0.01
=head1 SYNOPSIS
=head3 Use as a module
use Pg::Reindex qw(prepare rebuild);
prepare($dbh, \@namespaces, \@tables, \@indexes);
rebuild($dbh, \%options, $dryrun);
=head3 Run as a perl script
perl `perldoc -l Pg::Reindex` \
[--help] \
[--server=localhost] \
[--port=5432] \
[--user=postgres] \
[--password=PASSWORD] \
[--table=TABLE] ... \
[--namespace=NAMESPACE] ... \
[--index=INDEX] ... \
[--[no]validate] \
[--high_txn_lag=BYTES] \
[--log_txn_lag=BYTES] \
[--[no]dryrun] \
[prepare|continue]
=head1 DESCRIPTION
Postgresql indexes should be rebuilt on a regular basis for good performance.
This can be done with the C<REINDEX> command, however, building indexes this way
requires an exclusive lock on the table. On the other hand, using
C<CREATE INDEX CONCURRENTLY> avoids this lock.
C<Pg::Reindex> builds new indexes using C<CREATE INDEX CONCURRENTLY>. Then it
starts a transaction for each index in which it drops the old index and
renames the new one.
It handles normal indexes and C<PRIMARY KEY>, C<FOREIGN KEY> and C<UNIQUE>
constraints.
=head2 Streaming replication and throttling
Before creating the next index, the streaming replication lag is checked to
be below a certain limit. If so, nothing special happens and the index is
built.
Otherwise, C<rebuild> waits for the replicas to catch up. When the lag
drops under a second limit, the C<rebuild> does not immediately continue.
Instead it waits for another 30 seconds and checks the lag every second
within that period. Only if the lag stays below the limit for the whole
time, execution is continued. This grace period is to deal with the fact
that a wal sender process may suddenly disappear and reappear after a
few seconds. Without the grace period the program may encounter a false
drop below the limit and hence continue. For large indexes this adds a
lot of lag.
=head1 USING AS A MODULE
To use Pg::Reindex as a module, first you need to load the
Pg::Reindex module:
use Pg::Reindex qw(prepare rebuild);
use strict;
(The C<use strict;> isn't required but is strongly recommended.)
Then you need to L</prepare> the indexes that you want rebuilt.
You can filter by combinations of namespace, tables, and indexes.
prepare($dbh, \@opt_namespaces,\@opt_tables, \@opt_indexes);
After "preparing" the set of indexes to be rebuilt, then you rebuild them:
rebuild( $dbh, { ThrottleOn => 10000000,
ThrottleOff => 100000, Validate => 1 }, $opt_dryrun);
=head2 SUBROUTINES/METHODS
=head3 prepare
C<prepare> determines the list of indexes that would be re-indexed, and
sets up the data structures used by C<rebuild>. C<prepare> must be called
before C<rebuild> is called.
C<prepare> creates a new schema named C<reindex> with 2 tables,
C<worklist> and C<log>. C<Worklist> is created as C<UNLOGGED>
table. C<prepare> saves information on all indexes that need to be rebuilt
to C<worklist>. The information in C<worklist> is used by C<rebuild>.
=over
=item $dbh
DBI database handle to the database whose indexes are to be reindexed.
=item \@namespaces
Rebuild only indexes in the C<namespaces>. If C<namespaces> is empty,
indexes in all namespaces except the following are considered:
those beginning with C<pg_>, in C<information_schema>i, or are
C<sequences> namespaces.
=item \@tables
lib/Pg/Reindex.pm view on Meta::CPAN
The port to connect to.
Default: 5432
=item --user
The user.
Default: postgres
=item --password
a file name or open file descriptor where to read the password from.
If the parameter value consists of only digits, it's evaluated as file
descriptor.
There is no default.
A convenient way to specify the password on the BASH command line is
reindex.pl --password=3 3<<<my_secret
That way the password appears in F<.bash_history>. But that file is
usually only readable to the owner.
=item --table
Reindex only indexes that belong to the specified table.
This option can be given multiple times.
If C<--table>, C<--namespace> and C<--index> are given simultaneously,
only indexes satisfying all conditions are considered.
=item --namespace
Without this option only namespaces are considered that are not in
beginning with C<pg_>. Also C<information_schema> or C<sequences>
namespaces are omitted.
If C<--table>, C<--namespace> and C<--index> are given simultaneously,
only indexes satisfying all conditions are considered.
=item --index
If C<--table>, C<--namespace> and C<--index> are given simultaneously,
only indexes satisfying all conditions are considered.
=item --[no]validate
validate C<FOREIGN KEY> constraints or leave them C<NOT VALID>. Default
it to validate.
=item --[no]dryrun
don't modify the database but print the essential SQL statements.
=item --high-txn-lag
the upper limit streaming replicas may lag behind in bytes.
Default is 10,000,000.
=item --low-txn-lag
the lower limit in bytes when execution may be continued after it has been
interrupted due to exceeding C<high_txn_lag>.
Default is 100,000
=item --help
print this help
=back
=head1 AUTHOR
BINARY, C<< <binary at cpan.org> >>
=head1 BUGS
Please report any bugs or feature requests to C<bug-pg-reindex at rt.cpan.org>, or through
the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Pg-Reindex>. I will be notified, and then you'll
automatically be notified of progress on your bug as I make changes.
=head1 LICENSE AND COPYRIGHT
Copyright 2015 Binary Ltd.
This program is free software; you can redistribute it and/or modify it
under the terms of the the Artistic License (2.0). You may obtain a
copy of the full license at:
L<http://www.perlfoundation.org/artistic_license_2_0>
Any use, modification, and distribution of the Standard or Modified
Versions is governed by this Artistic License. By using, modifying or
distributing the Package, you accept this license. Do not use, modify,
or distribute the Package, if you do not accept this license.
If your Modified Version has been derived from a Modified Version made
by someone other than you, you are nevertheless required to ensure that
your Modified Version complies with the requirements of this license.
This license does not grant you the right to use any trademark, service
mark, tradename, or logo of the Copyright Holder.
This license includes the non-exclusive, worldwide, free-of-charge
patent license to make, have made, use, offer to sell, sell, import and
otherwise transfer the Package with respect to any patent claims
licensable by the Copyright Holder that are necessarily infringed by the
Package. If you institute patent litigation (including a cross-claim or
counterclaim) against any party alleging that the Package constitutes
direct or contributory patent infringement, then this Artistic License
to you shall terminate on the date that such litigation is filed.
Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT HOLDER
AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES.
THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
( run in 1.486 second using v1.01-cache-2.11-cpan-140bd7fdf52 )