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Implement IndexLength in pt-table-checksum and pt-online-schema-change. Tag the IndexLength queries with "key_len" and make n_index_cols optional--get full key_len if not given.

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This commit is contained in:
Daniel Nichter
2012-06-11 12:54:26 -04:00
parent 4f3bdabf7c
commit 3f2295ec46
5 changed files with 377 additions and 42 deletions
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38
lib/IndexLength.pm
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@@ -51,7 +51,7 @@ sub new {
# the first N left-most columns of the index.
sub index_length {
my ($self, %args) = @_;
my @required_args = qw(Cxn tbl index n_index_cols);
my @required_args = qw(Cxn tbl index);
foreach my $arg ( @required_args ) {
die "I need a $arg argument" unless $args{$arg};
}
@@ -62,18 +62,32 @@ sub index_length {
die "Index $args{index} does not exist in table $args{tbl}->{name}"
unless $args{tbl}->{tbl_struct}->{keys}->{$args{index}};
my $index_struct = $args{tbl}->{tbl_struct}->{keys}->{$args{index}};
my $index_cols = $index_struct->{cols};
my $n_index_cols = $args{n_index_cols};
if ( !$n_index_cols || $n_index_cols > @$index_cols ) {
$n_index_cols = scalar @$index_cols;
}
# Get the first row with non-NULL values.
my $vals = $self->_get_first_values(%args);
my $vals = $self->_get_first_values(
%args,
n_index_cols => $n_index_cols,
);
# Make an EXPLAIN query to scan the range and execute it.
my $sql = $self->_make_range_query(%args, vals => $vals);
my $sql = $self->_make_range_query(
%args,
n_index_cols => $n_index_cols,
vals => $vals,
);
my $sth = $cxn->dbh()->prepare($sql);
PTDEBUG && _d($sth->{Statement}, 'params:', @$vals);
$sth->execute(@$vals);
my $row = $sth->fetchrow_hashref();
$sth->finish();
PTDEBUG && _d('Range scan:', Dumper($row));
return $row->{key_len};
return $row->{key_len}, $row->{key};
}
sub _get_first_values {
@@ -86,11 +100,9 @@ sub _get_first_values {
my $q = $self->{Quoter};
my $index_struct = $tbl->{tbl_struct}->{keys}->{$index};
my $index_cols = $index_struct->{cols};
$n_index_cols = @$index_cols - 1 if $n_index_cols > @$index_cols;
# Select just the index columns.
my $index_struct = $tbl->{tbl_struct}->{keys}->{$index};
my $index_cols = $index_struct->{cols};
my $index_columns = join (', ',
map { $q->quote($_) } @{$index_cols}[0..($n_index_cols - 1)]);
@@ -104,7 +116,7 @@ sub _get_first_values {
. "FROM $tbl->{name} FORCE INDEX (" . $q->quote($index) . ") "
. "WHERE " . join(' AND ', @where)
. " ORDER BY $index_columns "
. "LIMIT 1"; # only need 1 row
. "LIMIT 1 /*key_len*/"; # only need 1 row
PTDEBUG && _d($sql);
my $vals = $cxn->dbh()->selectrow_arrayref($sql);
return $vals;
@@ -122,11 +134,12 @@ sub _make_range_query {
my $index_struct = $tbl->{tbl_struct}->{keys}->{$index};
my $index_cols = $index_struct->{cols};
$n_index_cols = @$index_cols - 1 if $n_index_cols > @$index_cols;
# All but the last index col = val.
my @where;
if ( $n_index_cols > 1 ) {
# -1 for zero-index array as usual, then -1 again because
# we don't want the last column; that's added below.
foreach my $n ( 0..($n_index_cols - 2) ) {
my $col = $index_cols->[$n];
my $val = $vals->[$n];
@@ -137,12 +150,13 @@ sub _make_range_query {
# The last index col > val. This causes the range scan using just
# the N left-most index columns.
my $col = $index_cols->[$n_index_cols - 1];
my $val = $vals->[$n_index_cols - 1];
my $val = $vals->[-1]; # should only be as many vals as cols
push @where, $q->quote($col) . " >= ?";
my $sql = "EXPLAIN SELECT /*!40001 SQL_NO_CACHE */ * "
. "FROM $tbl->{name} FORCE INDEX (" . $q->quote($index) . ") "
. "WHERE " . join(' AND ', @where);
. "WHERE " . join(' AND ', @where)
. " /*key_len*/";
return $sql;
}