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https://github.com/pawurb/activerecord-analyze

Add EXPLAIN ANALYZE to Rails Active Record query objects
https://github.com/pawurb/activerecord-analyze

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Add EXPLAIN ANALYZE to Rails Active Record query objects

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# ActiveRecord Analyze [![Gem Version](https://badge.fury.io/rb/activerecord-analyze.svg)](https://badge.fury.io/rb/activerecord-analyze) [![GH Actions](https://github.com/pawurb/activerecord-analyze/actions/workflows/ci.yml/badge.svg)](https://github.com/pawurb/activerecord-analyze/actions)



This gem adds an `analyze` method to Active Record query objects. It executes `EXPLAIN ANALYZE` on a query SQL.



You can check out this blog post for more info on how to [debug and fix slow queries in Rails apps](https://pawelurbanek.com/slow-rails-queries).



The following `format` options are supported `:json, :hash, :yaml, :text, :xml`. Especially the `:json` format is useful because it let's you visualize a query plan using [a visualizer tool](https://tatiyants.com/pev/#/plans/new).



![PG Query visualizer plan](https://raw.githubusercontent.com/pawurb/activerecord-analyze/main/query-plan.png)



## Installation



In your Gemfile:



```ruby



gem 'activerecord-analyze'



```



## Options



The `analyze` method supports the following EXPLAIN query options ([PostgreSQL docs reference](https://www.postgresql.org/docs/12/sql-explain.html)):



```

buffers: [ boolean ]

verbose: [ boolean ]

costs: [ boolean ]

settings: [ boolean ]

timing: [ boolean ]

summary: [ boolean ]

format: { :text | :json | :xml | :yaml | :pretty_json }

```



You can execute it like that:



```ruby



puts User.all.analyze(

  format: :pretty_json, # :pretty_json format option generates a formatted JSON output

  verbose: true,

  costs: true,

  settings: true,

  buffers: true,

  timing: true,

  summary: true

)



# EXPLAIN (FORMAT JSON, ANALYZE, VERBOSE, COSTS, SETTINGS, BUFFERS, TIMING, SUMMARY)

# SELECT "users".* FROM "users"

# [

#   {

#     "Plan": {

#       "Node Type": "Seq Scan",

#       "Parallel Aware": false,

#       "Relation Name": "users",

#       "Schema": "public",

#       "Alias": "users",

#       "Startup Cost": 0.00,

#       "Total Cost": 11.56,

#       "Plan Rows": 520,

#       "Plan Width": 127,

#       "Actual Startup Time": 0.006,

#       "Actual Total Time": 0.007,

#       "Actual Rows": 2,

#       "Actual Loops": 1,

#       "Output": ["id", "team_id", "email"],

#       "Shared Hit Blocks": 1,

#       "Shared Read Blocks": 0,

#       "Shared Dirtied Blocks": 0,

#       "Shared Written Blocks": 0,

#       "Local Hit Blocks": 0,

#       "Local Read Blocks": 0,

#       "Local Dirtied Blocks": 0,

#       "Local Written Blocks": 0,

#       "Temp Read Blocks": 0,

#       "Temp Written Blocks": 0,

#       "I/O Read Time": 0.000,

#       "I/O Write Time": 0.000

#     },

#     "Settings": {

#       "cpu_index_tuple_cost": "0.001",

#       "cpu_operator_cost": "0.0005",

#       "cpu_tuple_cost": "0.003",

#       "effective_cache_size": "10800000kB",

#       "max_parallel_workers_per_gather": "1",

#       "random_page_cost": "2",

#       "work_mem": "100MB"

#     },

#     "Planning Time": 0.033,

#     "Triggers": [

#     ],

#     "Execution Time": 0.018

#   }

# ]



```



Optionally you can disable running the `ANALYZE` query and only generate the plan:



```ruby



User.all.analyze(analyze: false)



# EXPLAIN ANALYZE for: SELECT "users".* FROM "users"

#                         QUERY PLAN

# ----------------------------------------------------------

#  Seq Scan on users  (cost=0.00..15.20 rows=520 width=127)



```



### Analyzing raw SQL queries



You can also use a raw SQL query string to generate an EXPLAIN ANALYZE output:



```ruby

query = "SELECT * FROM users WHERE email = '[email protected]'"



puts ActiveRecordAnalyze.analyze_sql(query, { format: :json })



# [

# {

#    "Plan": {

#      "Node Type": "Seq Scan",

#      "Parallel Aware": false,

#      "Relation Name": "users",

#      "Alias": "users",

#      "Startup Cost": 0.00,

#      "Total Cost": 18.75,

#      "Plan Rows": 4,

#      "Plan Width": 88,

#      "Actual Startup Time": 0.010,

#      "Actual Total Time": 0.018,

#      "Actual Rows": 0,

#      "Actual Loops": 1,

#      "Filter": "((email)::text = '[email protected]'::text)",

#      "Rows Removed by Filter": 0

#    },

#    "Planning Time": 0.052,

#    "Triggers": [

#    ],

#    "Execution Time": 0.062

# }

# ]

```



This feature is helpful in analyzing SQL queries extracted from the logs.



### Disclaimer



It is a bit experimental and can break with new Rails release.