Adds API support for Project Deployment Frequency

Related to Issues

• API support for Deployment Frequency: #279039 (closed)

What does this MR do?

Creates an API to access Deployment Frequency data at the Project level.

Does this MR meet the acceptance criteria?

Database

Migrations:

± bin/rake db:migrate:up VERSION=20201211042306
== 20201211042306 AddDeploymentsFinderByFinishedAtIndex: migrating ============
-- transaction_open?()
   -> 0.0000s
-- index_exists?(:deployments, [:project_id, :finished_at], {:where=>"status = 2", :name=>"index_deployments_on_project_and_finished", :algorithm=>:concurrently})
   -> 0.0097s
-- execute("SET statement_timeout TO 0")
   -> 0.0001s
-- add_index(:deployments, [:project_id, :finished_at], {:where=>"status = 2", :name=>"index_deployments_on_project_and_finished", :algorithm=>:concurrently})
   -> 0.0152s
-- execute("RESET ALL")
   -> 0.0001s
== 20201211042306 AddDeploymentsFinderByFinishedAtIndex: migrated (0.0257s) ===

± bin/rake db:migrate:down VERSION=20201211042306
== 20201211042306 AddDeploymentsFinderByFinishedAtIndex: reverting ============
-- transaction_open?()
   -> 0.0000s
-- index_exists?(:deployments, [:project_id, :finished_at], {:where=>"status = 2", :name=>"index_deployments_on_project_and_finished", :algorithm=>:concurrently})
   -> 0.0074s
-- execute("SET statement_timeout TO 0")
   -> 0.0001s
-- remove_index(:deployments, {:where=>"status = 2", :name=>"index_deployments_on_project_and_finished", :algorithm=>:concurrently, :column=>[:project_id, :finished_at]})
   -> 0.0104s
-- execute("RESET ALL")
   -> 0.0001s
== 20201211042306 AddDeploymentsFinderByFinishedAtIndex: reverted (0.0185s) ===

Queries:

SELECT
    "deployments".*
FROM
    "deployments"
    INNER JOIN "environments" ON "environments"."id" = "deployments"."environment_id"
WHERE
    "deployments"."project_id" = :project_id
    AND (deployments.created_at >= :start_datetime)
    AND (deployments.created_at < :end_datetime)
    AND "deployments"."status" = 2
    AND "environments"."name" = :environment_name;

Plan with execution:

 Nested Loop  (cost=1.00..55847.19 rows=918 width=139) (actual time=1.445..1111.047 rows=36331 loops=1)
   Buffers: shared hit=662633 read=24746
   I/O Timings: read=642.676
   ->  Index Scan using index_deployments_on_project_and_finished on public.deployments  (cost=0.57..18593.04 rows=14577 width=139) (actual time=0.390..774.724 rows=140998 loops=1)
         Index Cond: ((deployments.project_id = 7764) AND (deployments.finished_at >= (now() - '30 days'::interval)) AND (deployments.finished_at < now()))
         Buffers: shared hit=96424 read=24745
         I/O Timings: read=641.462
   ->  Index Scan using environments_pkey on public.environments  (cost=0.43..2.56 rows=1 width=4) (actual time=0.002..0.002 rows=0 loops=140998)
         Index Cond: (environments.id = deployments.environment_id)
         Filter: ((environments.name)::text = 'production'::text)
         Rows Removed by Filter: 1
         Buffers: shared hit=566209 read=1
         I/O Timings: read=1.214

Recommendations:

Query processes too much data to return a relatively small number of rows. – Reduce data cardinality as early as possible during the execution, using one or several of the following techniques: new indexes, partitioning, query rewriting, denormalization. See the visualization of the plan to understand which plan nodes are the main bottlenecks. Show details

Add LIMIT – The number of rows in the result set is too big. Limit number of rows. Show details

Specialized index needed – The index(es) currently used does not serve quite well for the needs of this query (notice Rows Removed by Filter: ..., meaning that the index fetched many non-target rows). Consider adding more specialized index(es). Show details

Summary:

Time: 1.115 s
  - planning: 0.906 ms
  - execution: 1.114 s
    - I/O read: 642.676 ms
    - I/O write: 0.000 ms

Shared buffers:
  - hits: 662633 (~5.10 GiB) from the buffer pool
  - reads: 24746 (~193.30 MiB) from the OS file cache, including disk I/O
  - dirtied: 0
  - writes: 0

Permalink: https://postgres.ai/console/gitlab/gitlab-production-tunnel/sessions/1515/commands/5068. (edited)

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

.gitlab/issue_templates/Doc Review.md

@@ -3,7 +3,7 @@
 
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      and assign the technical writer who is
-     [listed for that stage](https://about.gitlab.com/handbook/product/product-categories/#devops-stages). -->
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 ## References