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Add --chunk-index-columns to pt-table-checksum.

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This commit is contained in:
Daniel Nichter
2012-06-11 08:07:18 -04:00
parent 583bc2957e
commit 823cedd9ba
2 changed files with 37 additions and 25 deletions
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33
bin/pt-table-checksum
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@@ -2294,6 +2294,7 @@ sub generate_asc_stmt {
@asc_cols = $asc_cols[0];
}
elsif ( my $n = $args{n_index_cols} ) {
$n = scalar @asc_cols if $n > @asc_cols;
PTDEBUG && _d('Ascending only first', $n, 'columns');
@asc_cols = @asc_cols[0..($n-1)];
}
@@ -6173,11 +6174,7 @@ sub main {
# Parse --chunk-index INDEX:N where N is the number of
# left-most columns of INDEX to use.
# https://bugs.launchpad.net/percona-toolkit/+bug/1010232
my ($chunk_index, $n_chunk_index_cols)
= split(':', $o->get('chunk-index') || '');
if ( defined $chunk_index && $chunk_index eq '' ) {
$o->save_error('--chunk-index cannot be an empty string');
}
my $n_chunk_index_cols = $o->get('chunk-index-columns');
if ( defined $n_chunk_index_cols
&& (!$n_chunk_index_cols
|| $n_chunk_index_cols =~ m/\D/
@@ -7116,8 +7113,8 @@ sub main {
Cxn => $master_cxn,
tbl => $tbl,
chunk_size => $tbl->{chunk_size},
chunk_index => $chunk_index,
n_chunk_index_cols => $n_chunk_index_cols,
chunk_index => $o->get('chunk-index'),
n_chunk_index_cols => $o->get('chunk-index-columns'),
dml => $checksum_dml,
select => $checksum_cols,
past_dml => $checksum_dml,
@@ -8302,16 +8299,18 @@ when using this option; a poor choice of index could cause bad performance.
This is probably best to use when you are checksumming only a single table, not
an entire server.
This option supports a special syntax to select a prefix of the index instead of
the entire index. The syntax is NAME:N, where NAME is the name of the index, and
N is the number of columns you wish to use. This works only for compound
indexes, and is useful in cases where a bug in the MySQL query optimizer
(planner) causes it to scan a large range of rows instead of using the index to
locate starting and ending points precisely. This problem sometimes occurs on
indexes with many columns, such as 4 or more. If this happens, the tool might
print a warning related to the L<"--[no]check-plan"> option. Instructing
the tool to use only the first N columns from the index is a workaround for
the bug in some cases.
=item --chunk-index-columns
type: int
Use only this many left-most columns of a L<"--chunk-index">. This works
only for compound indexes, and is useful in cases where a bug in the MySQL
query optimizer (planner) causes it to scan a large range of rows instead
of using the index to locate starting and ending points precisely. This
problem sometimes occurs on indexes with many columns, such as 4 or more.
If this happens, the tool might print a warning related to the
L<"--[no]check-plan"> option. Instructing the tool to use only the first
N columns of the index is a workaround for the bug in some cases.
=item --chunk-size