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title: “DORA - Lead Time for Changes” description: > DORA - Lead Time for Changes sidebar_position: 19

What is this metric?

The median amount of time for a commit to be deployed into production.

Why is it important?

This metric measures the time it takes to commit code to the production environment and reflects the speed of software delivery. A lower average change preparation time means that your team is efficient at coding and deploying your project.

Which dashboard(s) does it exist in

DORA dashboard. See live demo.

How is it calculated?

This metric is calculated by the median cycle time of the PRs deployed in a time range. A PR‘s cycle time is equal to the time a PR was deployed minus the PR’s first commit's authored_date.

See the picture above, there were three deployments in the last month: Deploy-1, Deploy-2 and Deploy-3. Six PRs were deployed during the same period.

Median Lead Time for Changes = The median cycle time of PR-1, PR-2, PR-3, PR-4, PR-5, PR-6

The way to calculate PR cycle time:

• PR-1 cycle time = Deploy-1‘s finished_date - PR-1’s first commit's authored_date
• PR-2 cycle time = Deploy-2‘s finished_date - PR-2’s first commit's authored_date
• PR-3 cycle time = Deploy-2‘s finished_date - PR-3’s first commit's authored_date
• PR-4 cycle time = Deploy-3‘s finished_date - PR-4’s first commit's authored_date
• PR-5 cycle time = Deploy-3‘s finished_date - PR-5’s first commit's authored_date
• PR-6 cycle time = Deploy-3‘s finished_date - PR-6’s first commit's authored_date

PR cycle time is pre-calculated when dora plugin is triggered. You can connect to DevLake's database and find it in the field change_timespan in table.pull_requests.

Below are the benchmarks for different development teams from Google‘s report. However, it’s difficult to tell which group a team falls into when the team's median lead time for changes is between one week and one month. Therefore, DevLake provides its own benchmarks to address this problem:

Groups	Benchmarks	DevLake Benchmarks
Elite performers	Less than one hour	Less than one hour
High performers	Between one day and one week	Less than one week
Medium performers	Between one month and six months	Between one week and six months
Low performers	More than six months	More than six months

Data Sources Required

This metric relies on deployments collected in multiple ways:

• Open APIs of Jenkins, GitLab, GitHub, etc.
• Webhook for general CI tools.
• Releases and PR/MRs from GitHub, GitLab APIs, etc.

Transformation Rules Required

This metric relies on the deployment configuration in Jenkins, GitLab or GitHub transformation rules to let DevLake know what CI builds/jobs can be regarded as deployments.

SQL Queries

If you want to measure the monthly trend of median lead time for changes as the picture shown below, run the following SQL in Grafana.

with _pr_stats as (
-- get PRs' cycle lead time in each month
	SELECT
		pr.id,
		date_format(pr.merged_date,'%y/%m') as month,
		pr.change_timespan as pr_cycle_time
	FROM
		pull_requests pr
	WHERE
		pr.merged_date is not null
		and pr.change_timespan is not null
		and $__timeFilter(pr.merged_date)
),

_find_median_clt_each_month as (
	SELECT x.month, x.pr_cycle_time as med_change_lead_time 
	FROM _pr_stats x JOIN _pr_stats y ON x.month = y.month
	GROUP BY x.month, x.pr_cycle_time
	HAVING SUM(SIGN(1-SIGN(y.pr_cycle_time-x.pr_cycle_time)))/COUNT(*) > 0.5
),

_find_clt_rank_each_month as (
	SELECT
		*,
		rank() over(PARTITION BY month ORDER BY med_change_lead_time) as _rank 
	FROM
		_find_median_clt_each_month
),

_clt as (
	SELECT
		month,
		med_change_lead_time
	from _find_clt_rank_each_month
	WHERE _rank = 1
),

_calendar_months as(
-- to deal with the month with no incidents
	SELECT date_format(CAST((SYSDATE()-INTERVAL (month_index) MONTH) AS date), '%y/%m') as month
	FROM ( SELECT 0 month_index
			UNION ALL SELECT   1  UNION ALL SELECT   2 UNION ALL SELECT   3
			UNION ALL SELECT   4  UNION ALL SELECT   5 UNION ALL SELECT   6
			UNION ALL SELECT   7  UNION ALL SELECT   8 UNION ALL SELECT   9
			UNION ALL SELECT   10 UNION ALL SELECT  11
		) month_index
	WHERE (SYSDATE()-INTERVAL (month_index) MONTH) > SYSDATE()-INTERVAL 6 MONTH	
)

SELECT 
	cm.month,
	case 
		when _clt.med_change_lead_time is null then 0 
		else _clt.med_change_lead_time/60 end as med_change_lead_time_in_hour
FROM 
	_calendar_months cm
	left join _clt on cm.month = _clt.month
ORDER BY 1

If you want to measure in which category your team falls into as the picture shown below, run the following SQL in Grafana.

with _pr_stats as (
-- get PRs' cycle time in the selected period
	SELECT
		pr.id,
		pr.change_timespan as pr_cycle_time
	FROM
		pull_requests pr
	WHERE
		pr.merged_date is not null
		and pr.change_timespan is not null
		and $__timeFilter(pr.merged_date)
),

_median_change_lead_time as (
-- use median PR cycle time as the median change lead time
	SELECT x.pr_cycle_time as median_change_lead_time from _pr_stats x, _pr_stats y
	GROUP BY x.pr_cycle_time
	HAVING SUM(SIGN(1-SIGN(y.pr_cycle_time-x.pr_cycle_time)))/COUNT(*) > 0.5
	LIMIT 1
)

SELECT 
  CASE
    WHEN median_change_lead_time < 60 then "Less than one hour"
    WHEN median_change_lead_time < 7 * 24 * 60 then "Less than one week"
    WHEN median_change_lead_time < 180 * 24 * 60 then "Between one week and six months"
    ELSE "More than six months"
    END as median_change_lead_time
FROM _median_change_lead_time

How to improve?

• Break requirements into smaller, more manageable deliverables
• Optimize the code review process
• “Shift left”, start QA early and introduce more automated tests
• Integrate CI/CD tools to automate the deployment process