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feat: Improve innodb_redo_log_capacity recommendation #849

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merged 1 commit into from
Aug 29, 2025
Merged

feat: Improve innodb_redo_log_capacity recommendation #849

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187 changes: 119 additions & 68 deletions mysqltuner.pl
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Original file line number Diff line number Diff line change
Expand Up @@ -441,6 +441,20 @@ sub hr_bytes {
}
}

# Calculates the parameter passed in bytes, then rounds it to a practical power-of-2 value in GB.
sub hr_bytes_practical_rnd {
my $num = shift;
return "0B" unless defined($num) and $num > 0;

my $gbs = $num / (1024**3); # convert to GB
my $power_of_2_gb = 1;
while ($power_of_2_gb < $gbs) {
$power_of_2_gb *= 2;
}

return $power_of_2_gb . "G";
}

sub hr_raw {
my $num = shift;
return "0" unless defined($num);
Expand Down Expand Up @@ -6580,79 +6594,116 @@ sub mysql_innodb {
}
}
}
if ( $mycalc{'innodb_log_size_pct'} < 20
or $mycalc{'innodb_log_size_pct'} > 30 )
{
if ( defined $myvar{'innodb_redo_log_capacity'} ) {
badprint
"Ratio InnoDB redo log capacity / InnoDB Buffer pool size ("
. $mycalc{'innodb_log_size_pct'} . "%): "
. hr_bytes( $myvar{'innodb_redo_log_capacity'} ) . " / "
. hr_bytes( $myvar{'innodb_buffer_pool_size'} )
. " should be equal to 25%";
push( @adjvars,
"innodb_redo_log_capacity should be (="
. hr_bytes_rnd( $myvar{'innodb_buffer_pool_size'} / 4 )
. ") if possible, so InnoDB Redo log Capacity equals 25% of buffer pool size."
);
push( @generalrec,
"Be careful, increasing innodb_redo_log_capacity means higher crash recovery mean time"
);
}
else {
badprint "Ratio InnoDB log file size / InnoDB Buffer pool size ("
. $mycalc{'innodb_log_size_pct'} . "%): "
. hr_bytes( $myvar{'innodb_log_file_size'} ) . " * "
. $myvar{'innodb_log_files_in_group'} . " / "
. hr_bytes( $myvar{'innodb_buffer_pool_size'} )
. " should be equal to 25%";
push(
@adjvars,
"innodb_log_file_size should be (="
. hr_bytes_rnd(
(
defined $myvar{'innodb_buffer_pool_size'}
&& $myvar{'innodb_buffer_pool_size'} ne ''
? $myvar{'innodb_buffer_pool_size'}
: 0
) / (
defined $myvar{'innodb_log_files_in_group'}
&& $myvar{'innodb_log_files_in_group'} ne ''
&& $myvar{'innodb_log_files_in_group'} != 0
? $myvar{'innodb_log_files_in_group'}
: 1
) / 4
)
. ") if possible, so InnoDB total log file size equals 25% of buffer pool size."
);
push( @generalrec,
"Be careful, increasing innodb_log_file_size / innodb_log_files_in_group means higher crash recovery mean time"
);
}
if ( mysql_version_le( 5, 6, 2 ) ) {
push( @generalrec,
"For MySQL 5.6.2 and lower, total innodb_log_file_size should have a ceiling of (4096MB / log files in group) - 1MB."
);
}
# InnoDB Log File Size / InnoDB Redo Log Capacity Recommendations
# For MySQL < 8.0.30, the recommendation is based on innodb_log_file_size and innodb_log_files_in_group.
# For MySQL >= 8.0.30, innodb_redo_log_capacity replaces the old system.
if ( mysql_version_ge( 8, 0, 30 ) ) {
# New recommendation logic for MySQL >= 8.0.30
infoprint "InnoDB Redo Log Capacity is set to " . hr_bytes($myvar{'innodb_redo_log_capacity'});

my $innodb_os_log_written = $mystat{'Innodb_os_log_written'} || 0;
my $uptime = $mystat{'Uptime'} || 1;

if ($uptime > 3600) { # Only make a recommendation if server has been up for at least an hour
my $hourly_rate = $innodb_os_log_written / ( $uptime / 3600 );
my $suggested_redo_log_capacity_str = hr_bytes_practical_rnd($hourly_rate);
my $suggested_redo_log_capacity_bytes = hr_raw($suggested_redo_log_capacity_str);

infoprint "Hourly InnoDB log write rate: " . hr_bytes_rnd($hourly_rate) . "/hour";

if (hr_raw($myvar{'innodb_redo_log_capacity'}) < $hourly_rate) {
badprint "Your innodb_redo_log_capacity is not large enough to hold at least 1 hour of writes.";
push( @adjvars, "innodb_redo_log_capacity (>= " . $suggested_redo_log_capacity_str . ")" );
} else {
goodprint "Your innodb_redo_log_capacity is sized to handle more than 1 hour of writes.";
}

# Sanity check against total InnoDB data size
if ( defined $enginestats{'InnoDB'} and $enginestats{'InnoDB'} > 0 ) {
my $total_innodb_size = $enginestats{'InnoDB'};
if ( $suggested_redo_log_capacity_bytes > $total_innodb_size * 0.25 ) {
infoprint "The suggested innodb_redo_log_capacity (" . $suggested_redo_log_capacity_str . ") is more than 25% of your total InnoDB data size. This might be unnecessarily large.";
}
}
} else {
infoprint "Server uptime is less than 1 hour. Cannot make a reliable recommendation for innodb_redo_log_capacity.";
}
}
else {
if ( defined $myvar{'innodb_redo_log_capacity'} ) {
goodprint
"Ratio InnoDB Redo Log Capacity / InnoDB Buffer pool size: "
. hr_bytes( $myvar{'innodb_redo_log_capacity'} ) . "/"
. hr_bytes( $myvar{'innodb_buffer_pool_size'} )
. " should be equal to 25%";
# Keep existing logic for older versions
if ( $mycalc{'innodb_log_size_pct'} < 20
or $mycalc{'innodb_log_size_pct'} > 30 )
{
if ( defined $myvar{'innodb_redo_log_capacity'} ) {
badprint
"Ratio InnoDB redo log capacity / InnoDB Buffer pool size ("
. $mycalc{'innodb_log_size_pct'} . "%): "
. hr_bytes( $myvar{'innodb_redo_log_capacity'} ) . " / "
. hr_bytes( $myvar{'innodb_buffer_pool_size'} )
. " should be equal to 25%";
push( @adjvars,
"innodb_redo_log_capacity should be (="
. hr_bytes_rnd( $myvar{'innodb_buffer_pool_size'} / 4 )
. ") if possible, so InnoDB Redo log Capacity equals 25% of buffer pool size."
);
push( @generalrec,
"Be careful, increasing innodb_redo_log_capacity means higher crash recovery mean time"
);
}
else {
badprint "Ratio InnoDB log file size / InnoDB Buffer pool size ("
. $mycalc{'innodb_log_size_pct'} . "%): "
. hr_bytes( $myvar{'innodb_log_file_size'} ) . " * "
. $myvar{'innodb_log_files_in_group'} . " / "
. hr_bytes( $myvar{'innodb_buffer_pool_size'} )
. " should be equal to 25%";
push(
@adjvars,
"innodb_log_file_size should be (="
. hr_bytes_rnd(
(
defined $myvar{'innodb_buffer_pool_size'}
&& $myvar{'innodb_buffer_pool_size'} ne ''
? $myvar{'innodb_buffer_pool_size'}
: 0
) / (
defined $myvar{'innodb_log_files_in_group'}
&& $myvar{'innodb_log_files_in_group'} ne ''
&& $myvar{'innodb_log_files_in_group'} != 0
? $myvar{'innodb_log_files_in_group'}
: 1
) / 4
)
. ") if possible, so InnoDB total log file size equals 25% of buffer pool size."
);
push( @generalrec,
"Be careful, increasing innodb_log_file_size / innodb_log_files_in_group means higher crash recovery mean time"
);
}
if ( mysql_version_le( 5, 6, 2 ) ) {
push( @generalrec,
"For MySQL 5.6.2 and lower, total innodb_log_file_size should have a ceiling of (4096MB / log files in group) - 1MB."
);
}
}
else {
push( @generalrec,
"Before changing innodb_log_file_size and/or innodb_log_files_in_group read this: https://bit.ly/2TcGgtU"
);
goodprint "Ratio InnoDB log file size / InnoDB Buffer pool size: "
. hr_bytes( $myvar{'innodb_log_file_size'} ) . " * "
. $myvar{'innodb_log_files_in_group'} . "/"
. hr_bytes( $myvar{'innodb_buffer_pool_size'} )
. " should be equal to 25%";
if ( defined $myvar{'innodb_redo_log_capacity'} ) {
goodprint
"Ratio InnoDB Redo Log Capacity / InnoDB Buffer pool size: "
. hr_bytes( $myvar{'innodb_redo_log_capacity'} ) . "/"
. hr_bytes( $myvar{'innodb_buffer_pool_size'} )
. " should be equal to 25%";
}
else {
push( @generalrec,
"Before changing innodb_log_file_size and/or innodb_log_files_in_group read this: https://bit.ly/2TcGgtU"
);
goodprint "Ratio InnoDB log file size / InnoDB Buffer pool size: "
. hr_bytes( $myvar{'innodb_log_file_size'} ) . " * "
. $myvar{'innodb_log_files_in_group'} . "/"
. hr_bytes( $myvar{'innodb_buffer_pool_size'} )
. " should be equal to 25%";
}
}
}

Expand Down