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Rewriting pt-online-schema-change 2.1.1. Work in progress (this code doesn't work yet).

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This commit is contained in:
Daniel Nichter
2012-03-20 13:34:16 -06:00
parent f4c978c957
commit a17bdd65d3
5 changed files with 2720 additions and 2037 deletions
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113
lib/NibbleIterator.pm
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@@ -61,40 +61,25 @@ sub new {
die "I need a $arg argument" unless $args{$arg};
}
my ($cxn, $tbl, $chunk_size, $o, $q) = @args{@required_args};
# Die unless table can be nibbled, else return row estimate, nibble index,
# and if table can be nibbled in one chunk.
my $nibble_params = can_nibble(%args);
my $where = $o->get('where');
my ($row_est, $mysql_index) = get_row_estimate(%args, where => $where);
my $one_nibble = !defined $args{one_nibble} || $args{one_nibble}
? $row_est <= $chunk_size * $o->get('chunk-size-limit')
: 0;
PTDEBUG && _d('One nibble:', $one_nibble ? 'yes' : 'no');
if ( $args{resume}
&& !defined $args{resume}->{lower_boundary}
&& !defined $args{resume}->{upper_boundary} ) {
PTDEBUG && _d('Resuming from one nibble table');
$one_nibble = 1;
}
# Get an index to nibble by. We'll order rows by the index's columns.
my $index = _find_best_index(%args, mysql_index => $mysql_index);
if ( !$index && !$one_nibble ) {
die "There is no good index and the table is oversized.";
}
my $where = $o->get('where');
my $tbl_struct = $tbl->{tbl_struct};
my $ignore_col = $o->get('ignore-columns') || {};
my $all_cols = $o->get('columns') || $tbl_struct->{cols};
my @cols = grep { !$ignore_col->{$_} } @$all_cols;
my $self;
if ( $one_nibble ) {
if ( $nibble_params->{one_nibble} ) {
# If the chunk size is >= number of rows in table, then we don't
# need to chunk; we can just select all rows, in order, at once.
my $nibble_sql
= ($args{dml} ? "$args{dml} " : "SELECT ")
. ($args{select} ? $args{select}
: join(', ', map { $q->quote($_) } @cols))
. " FROM " . $q->quote(@{$tbl}{qw(db tbl)})
. " FROM $tbl->{name}"
. ($where ? " WHERE $where" : '')
. " /*checksum table*/";
PTDEBUG && _d('One nibble statement:', $nibble_sql);
@@ -103,7 +88,7 @@ sub new {
= "EXPLAIN SELECT "
. ($args{select} ? $args{select}
: join(', ', map { $q->quote($_) } @cols))
. " FROM " . $q->quote(@{$tbl}{qw(db tbl)})
. " FROM $tbl->{name}"
. ($where ? " WHERE $where" : '')
. " /*explain checksum table*/";
PTDEBUG && _d('Explain one nibble statement:', $explain_nibble_sql);
@@ -117,6 +102,7 @@ sub new {
};
}
else {
my $index = $nibble_params->{index}; # brevity
my $index_cols = $tbl->{tbl_struct}->{keys}->{$index}->{cols};
# Figure out how to nibble the table with the index.
@@ -132,7 +118,7 @@ sub new {
# Make SQL statements, prepared on first call to next(). FROM and
# ORDER BY are the same for all statements. FORCE IDNEX and ORDER BY
# are needed to ensure deterministic nibbling.
my $from = $q->quote(@{$tbl}{qw(db tbl)}) . " FORCE INDEX(`$index`)";
my $from = "$tbl->{name} FORCE INDEX(`$index`)";
my $order_by = join(', ', map {$q->quote($_)} @{$index_cols});
# The real first row in the table. Usually we start nibbling from
@@ -246,7 +232,7 @@ sub new {
};
}
$self->{row_est} = $row_est;
$self->{row_est} = $nibble_params->{row_est},
$self->{nibbleno} = 0;
$self->{have_rows} = 0;
$self->{rowno} = 0;
@@ -418,6 +404,52 @@ sub row_estimate {
return $self->{row_est};
}
sub can_nibble {
my (%args) = @_;
my @required_args = qw(Cxn tbl chunk_size OptionParser TableParser);
foreach my $arg ( @required_args ) {
die "I need a $arg argument" unless $args{$arg};
}
my ($cxn, $tbl, $chunk_size, $o) = @args{@required_args};
# About how many rows are there?
my ($row_est, $mysql_index) = get_row_estimate(
Cxn => $cxn,
tbl => $tbl,
where => $o->get('where'),
);
# Can all those rows be nibbled in one chunk? If one_nibble is defined,
# then do as it says; else, look at the chunk size limit.
my $one_nibble = !defined $args{one_nibble} || $args{one_nibble}
? $row_est <= $chunk_size * $o->get('chunk-size-limit')
: 0;
PTDEBUG && _d('One nibble:', $one_nibble ? 'yes' : 'no');
# Special case: we're resuming and there's no boundaries, so the table
# being resumed was originally nibbled in one chunk, so do the same again.
if ( $args{resume}
&& !defined $args{resume}->{lower_boundary}
&& !defined $args{resume}->{upper_boundary} ) {
PTDEBUG && _d('Resuming from one nibble table');
$one_nibble = 1;
}
# Get an index to nibble by. We'll order rows by the index's columns.
my $index = _find_best_index(%args, mysql_index => $mysql_index);
if ( !$index && !$one_nibble ) {
die "There is no good index and the table is oversized.";
}
# The table can be nibbled if this point is reached, else we would have
# died earlier. Return some values about nibbling the table.
return {
row_est => $row_est, # nibble about this many rows
index => $index, # using this index
one_nibble => $one_nibble, # if the table fits in one nibble/chunk
};
}
sub _find_best_index {
my (%args) = @_;
my @required_args = qw(Cxn tbl TableParser);
@@ -494,11 +526,11 @@ sub _find_best_index {
sub _get_index_cardinality {
my (%args) = @_;
my @required_args = qw(Cxn tbl index Quoter);
my ($cxn, $tbl, $index, $q) = @args{@required_args};
my @required_args = qw(Cxn tbl index);
my ($cxn, $tbl, $index) = @args{@required_args};
my $sql = "SHOW INDEXES FROM " . $q->quote(@{$tbl}{qw(db tbl)})
. " WHERE Key_name = '$index'";
my $sql = "SHOW INDEXES FROM $tbl->{name} "
. "WHERE Key_name = '$index'";
PTDEBUG && _d($sql);
my $cardinality = 1;
my $rows = $cxn->dbh()->selectall_hashref($sql, 'key_name');
@@ -511,22 +543,25 @@ sub _get_index_cardinality {
sub get_row_estimate {
my (%args) = @_;
my @required_args = qw(Cxn tbl OptionParser TableParser Quoter);
my ($cxn, $tbl, $o, $tp, $q) = @args{@required_args};
my @required_args = qw(Cxn tbl);
foreach my $arg ( @required_args ) {
die "I need a $arg argument" unless $args{$arg};
}
my ($cxn, $tbl) = @args{@required_args};
if ( $args{where} ) {
PTDEBUG && _d('WHERE clause, using explain plan for row estimate');
my $table = $q->quote(@{$tbl}{qw(db tbl)});
my $sql = "EXPLAIN SELECT * FROM $table WHERE $args{where}";
if ( !$args{where} && exists $tbl->{tbl_status} ) {
PTDEBUG && _d('Using table status for row estimate');
return $tbl->{tbl_status}->{rows} || 0;
}
else {
PTDEBUG && _d('Use EXPLAIN for row estimate');
my $sql = "EXPLAIN SELECT * FROM $tbl->{name} "
. "WHERE " . ($args{where} || '1=1');
PTDEBUG && _d($sql);
my $expl = $cxn->dbh()->selectrow_hashref($sql);
PTDEBUG && _d(Dumper($expl));
return ($expl->{rows} || 0), $expl->{key};
}
else {
PTDEBUG && _d('No WHERE clause, using table status for row estimate');
return $tbl->{tbl_status}->{rows} || 0;
}
}
sub _prepare_sths {