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simba
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reimplemented the outer join in perl with two separate queries and a 

judy bitmap. This is about 20 times faster (1 hour instead of 20 for
1.3E9 instances and 125E6 versions).
This commit is contained in:
hjp 2013-12-01 12:10:35 +00:00
parent 71e2f16454
commit 6982561a6d
1 changed files with 43 additions and 7 deletions
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50
scripts/remove_session
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@ -8,6 +8,7 @@ use warnings;
use strict;
use Simba::CA;
use Bit::Vector::Judy;
$| = 1;
@ -18,18 +19,19 @@ my $ca = Simba::CA->new({
my $dbh = $ca->{dbh};
for my $session (@ARGV) {
print "deleting session $session\n";
print "deleting instances of session $session\n";
my $n_instances = $dbh->do("delete from instances where session=?", {}, $session);
print "\t$n_instances instances deleted\n";
$dbh->commit();
}
remove_orphaned_sessions();
remove_orphaned_files();
#remove_orphaned_files();
remove_orphaned_versions();
$dbh->disconnect();
exit();
sub remove_orphaned_sessions {
print "deleting orphaned sessions\n";
my $sessions
= $dbh->selectcol_arrayref(
q{select s.id from instances i right outer join sessions s on i.session=s.id where i.id is null}
@ -43,6 +45,7 @@ sub remove_orphaned_sessions {
}
sub remove_orphaned_files {
print "deleting orphaned files\n";
my $files
= $dbh->selectcol_arrayref(
q{select f.id from instances i right outer join files f on i.file=f.id where i.id is null}
@ -56,14 +59,47 @@ sub remove_orphaned_files {
}
sub remove_orphaned_versions {
my $versions
= $dbh->selectcol_arrayref(
q{select v.id from instances i right outer join versions2 v on i.version=v.id where i.id is null}
);
# This differs from the other two because mysql doesn't find a good plan for
# the outer join: It does an index lookup on instances for every row of
# versions2. For the other tables that's good because sessions and files are
# much smaller than instances, but there is only about a factor of 10
# between versions2 and instances, so reading both sequentally is much
# better. Suprisingly, perl is also faster at eliminating duplicates than
# mysql, so just doing two selects and doing all the work in perl is faster
# than “select distinct … minus …” though not much.
print "deleting orphaned versions\n";
my $sth;
for my $version (@$versions) {
$dbh->{'mysql_use_result'} = 1;
my $versions = Bit::Vector::Judy->new;
$sth = $dbh->prepare("select id from versions2");
$sth->execute;
my $i = 0;
while (my $version = $sth->fetchrow_array) {
if ($i % 1_000_000 == 0) {
print "\t$i records from versions processed, ", $versions->count(0, -1), " versions found\n";
}
$versions->set($version);
$i++;
}
$sth = $dbh->prepare("select version from instances");
$sth->execute;
$i = 0;
while (my $version = $sth->fetchrow_array) {
if ($i % 1_000_000 == 0) {
print "\t$i records from instances processed, ", $versions->count(0, -1), " versions left\n";
}
$versions->unset($version);
$i++;
}
$dbh->{'mysql_use_result'} = 0;
for (my $version = $versions->first; $version; $version = $versions->next($version)) {
$dbh->do(q{delete from versions2 where id=?}, {}, $version);
print "\tversion $version deleted\n";
}
$dbh->commit();
}
# vim: tw=132