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Viewing changes to tests/randgen/lib/GenTest/Transform/DisableChosenPlan.pm

  • Committer: Package Import Robot
  • Author(s): Clint Byrum
  • Date: 2012-06-19 10:46:49 UTC
  • mfrom: (1.1.6)
  • mto: This revision was merged to the branch mainline in revision 29.
  • Revision ID: package-import@ubuntu.com-20120619104649-e2l0ggd4oz3um0f4
Tags: upstream-7.1.36-stable
Import upstream version 7.1.36-stable

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tests/randgen/lib/GenTest/Transform/DisableChosenPlan.pm
 
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# This program is free software; you can redistribute it and/or modify
 
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# it under the terms of the GNU General Public License as published by
 
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# the Free Software Foundation; version 2 of the License.
 
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#
 
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# This program is distributed in the hope that it will be useful, but
 
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# WITHOUT ANY WARRANTY; without even the implied warranty of
 
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 
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# General Public License for more details.
 
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#
 
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# You should have received a copy of the GNU General Public License
 
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# along with this program; if not, write to the Free Software
 
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# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
 
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# USA
 
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package GenTest::Transform::DisableChosenPlan;
 
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require Exporter;
 
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@ISA = qw(GenTest GenTest::Transform);
 
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use strict;
 
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use lib 'lib';
 
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use GenTest;
 
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use GenTest::Transform;
 
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use GenTest::Constants;
 
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use Data::Dumper;
 
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#
 
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# This Transform runs EXPLAIN on the query, determines which (subquery) optimizations were used
 
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# and disables them so that the query can be rerun with a "second-best" plan. This way the best and
 
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# the "second best" plans are checked against one another.
 
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#
 
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# This has the following benefits:
 
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# 1. The query plan that is being validated is the one actually chosen by the optimizer, so that one can
 
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# run a comprehensive subquery test without having to manually fiddle with @@optimizer_switch
 
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# 2. The plan that is used for validation is hopefully also fast enough, as compared to using unindexed nested loop
 
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# joins with re-execution of the enitre subquery for each loop.
 
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#
 
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my @explain2switch = (
 
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        [ 'sort_intersect'      => "optimizer_switch='index_merge_sort_intersection=off'"],
 
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        [ 'intersect'           => "optimizer_switch='index_merge_intersection=off'"],
 
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        [ 'firstmatch'          => "optimizer_switch='firstmatch=off'" ],
 
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        [ '<expr_cache>'        => "optimizer_switch='subquery_cache=off'" ],
 
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        [ 'materializ'          => "optimizer_switch='materialization=off'" ],  # hypothetical
 
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        [ 'semijoin'            => "optimizer_switch='semijoin=off'" ],
 
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        [ 'loosescan'           => "optimizer_switch='loosescan=off'" ],
 
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        [ '<exists>'            => "optimizer_switch='in_to_exists=off'" ],
 
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        [ qr{BNLH|BKAH}         => "optimizer_switch='join_cache_hashed=off'" ],        
 
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        [ 'BKA'                 => "optimizer_switch='join_cache_bka=off'" ],
 
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        [ 'incremental'         => "optimizer_switch='join_cache_incremental=off'" ],
 
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        [ 'join buffer'         => "join_cache_level=0" ],
 
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        [ 'join buffer'         => "optimizer_join_cache_level=0" ],
 
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        [ 'mrr'                 => "optimizer_use_mrr='disable'" ],
 
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        [ 'index condition'     => "optimizer_switch='index_condition_pushdown=off'" ]
 
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);
 
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my $available_switches;
 
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sub transform {
 
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        my ($class, $original_query, $executor) = @_;
 
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        if (not defined $available_switches) {
 
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                my $optimizer_switches = $executor->dbh()->selectrow_array('SELECT @@optimizer_switch');
 
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                my @optimizer_switches = split(',', $optimizer_switches);
 
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                foreach my $optimizer_switch (@optimizer_switches) {
 
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                        my ($switch_name, $switch_value) = split('=', $optimizer_switch);
 
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                        $available_switches->{"optimizer_switch='$switch_name=off'"}++;
 
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                }
 
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                if ($executor->dbh()->selectrow_array('SELECT @@optimizer_use_mrr')) {
 
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                        $available_switches->{"optimizer_use_mrr='disable'"}++;
 
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                }
 
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                if ($executor->dbh()->selectrow_array('SELECT @@join_cache_level')) {
 
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                        $available_switches->{"join_cache_level=0"}++;
 
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                }
 
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                if ($executor->dbh()->selectrow_array('SELECT @@optimizer_join_cache_level')) {
 
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                        $available_switches->{"optimizer_join_cache_level=0"}++;
 
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                }
 
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        }
 
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        return STATUS_WONT_HANDLE if $original_query !~ m{^\s*SELECT}sio;
 
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        my $original_explain = $executor->execute("EXPLAIN EXTENDED $original_query");
 
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        if ($original_explain->status() == STATUS_SERVER_CRASHED) {
 
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                return STATUS_SERVER_CRASHED;
 
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        } elsif ($original_explain->status() ne STATUS_OK) {
 
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                return STATUS_ENVIRONMENT_FAILURE;
 
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        }
 
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        my $original_explain_string = Dumper($original_explain->data())."\n".Dumper($original_explain->warnings());
 
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        my @transformed_queries;
 
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        foreach my $explain2switch (@explain2switch) {
 
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                my ($explain_fragment, $optimizer_switch) = ($explain2switch->[0], $explain2switch->[1]);
 
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                next if not exists $available_switches->{$optimizer_switch};
 
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                if ($original_explain_string =~ m{$explain_fragment}si) {
 
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                        my ($switch_name) = $optimizer_switch =~ m{^(.*?)=}sgio;
 
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                        push @transformed_queries, (
 
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                                'SET @switch_saved = @@'.$switch_name.';',
 
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                                "SET SESSION $optimizer_switch;",
 
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                                "$original_query /* TRANSFORM_OUTCOME_UNORDERED_MATCH */ ;",
 
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                                'SET SESSION '.$switch_name.'=@switch_saved'
 
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                        );
 
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                }
 
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        }
 
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        if ($#transformed_queries > -1) {
 
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                return \@transformed_queries;
 
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        } else {
 
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                return STATUS_WONT_HANDLE;
 
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        }
 
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}
 
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1;