Merge pull request #10 from fractaledmind/fingerprint

Use a fingerprint for error uniqueness instead of a multi-column index

UPGRADE.md

@@ -0,0 +1,69 @@
+# Solid Errors Upgrade Guide
+
+Follow this guide to upgrade your Solid Errors implementation to the next version
+
+## Solid Errors 0.4.0
+
+We've added a `fingerprint` column to the `solid_errors` table and changed the `exception_class`, `message`, `severity`, and `source` columns to be limitless `text` type columns. This allows the unique index on the table to be on the single `fingerprint` column, which is a SHA256 hash of the `exception_class`, `message`, `severity`, and `source` columns. This change resolves problems with the unique index being too large as well as problems with one of the data columns being truncated. But, it requires a migration to update the `solid_errors` table.
+
+Create a migration for whatever database stores your errors:
+```bash
+rails generate migration UpgradeSolidErrors --database {name_of_errors_database}
+```
+
+Then, update the migration file with the following code:
+```ruby
+class UpgradeSolidErrors < ActiveRecord::Migration[7.1]
+  def up
+    change_column :solid_errors, :exception_class, :text, null: false, limit: nil
+    change_column :solid_errors, :message, :text, null: false, limit: nil
+    change_column :solid_errors, :severity, :text, null: false, limit: nil
+    change_column :solid_errors, :source, :text, null: true, limit: nil
+    add_column :solid_errors, :fingerprint, :string, limit: 64
+    add_index :solid_errors, :fingerprint, unique: true
+    remove_index :solid_errors, [:exception_class, :message, :severity, :source], unique: true
+  end
+
+  def down
+    change_column :solid_errors, :exception_class, :string, null: false, limit: 200
+    change_column :solid_errors, :message, :string, null: false, limit: nil
+    change_column :solid_errors, :severity, :string, null: false, limit: 25
+    change_column :solid_errors, :source, :string, null: true, limit: nil
+    remove_index :solid_errors, [:fingerprint], unique: true
+    remove_column :solid_errors, :fingerprint, :string, limit: 64
+    add_index :solid_errors, [:exception_class, :message, :severity, :source], unique: true
+  end
+end
+```
+
+Then, run this migration:
+```bash
+rails db:migrate:{name_of_errors_database}
+```
+
+Once the migration is complete, you will next need to fingerprint any existing errors in your database. This can be done using the following Ruby script, which can be put in a Rake task, a data migration, or simply done in the console:
+```ruby
+SolidErrors::Error.where(fingerprint: nil).find_each do |error|
+  error_attributes = error.attributes.slice('exception_class', 'message', 'severity', 'source')
+  fingerprint = Digest::SHA256.hexdigest(error_attributes.values.join)
+  error.update_attribute(:fingerprint, fingerprint)
+end
+```
+
+You will need to run this script _as soon as the schema migration_ is complete so that you can fingerprint all existing errors before new errors with pre-generated fingerprints are recorded.
+
+Once you have migrated all existing errors to include a fingerprint, the final step is to run one more schema migration to mark the `fingerprint` column as non-nullable. You can generate a migration for this with the following command:
+```bash
+rails generate migration SolidErrorFingerprintNonNullable --database {name_of_errors_database}
+```
+
+Then, update the migration file with the following code:
+```ruby
+class SolidErrorFingerprintNonNullable < ActiveRecord::Migration[7.1]
+  def change
+    change_column_null :solid_errors, :fingerprint, false
+  end
+end
+```
+
+Once this migration has been successfully run in production, your upgrade to Solid Errors 0.4.0 is complete!

lib/generators/solid_errors/install/templates/create_solid_errors_tables.rb.erb

@@ -3,15 +3,14 @@
 class CreateSolidErrorsTables < ActiveRecord::Migration<%= migration_version %>
   def change
     create_table :solid_errors do |t|
-      t.string :exception_class, null: false, limit: 200
-      t.string :message, null: false
-      t.string :severity, null: false, limit: 25
-      t.string :source
+      t.text :exception_class, null: false
+      t.text :message, null: false
+      t.text :severity, null: false
+      t.text :source
       t.datetime :resolved_at, index: true
+      t.string :fingerprint, null: false, limit: 64, index: { unique: true }
 
       t.timestamps
-
-      t.index [:exception_class, :message, :severity, :source], unique: true, name: "solid_error_uniqueness_index"
     end
 
     create_table :solid_errors_occurrences do |t|

lib/solid_errors/subscriber.rb

@@ -30,10 +30,11 @@ def report(error, handled:, severity:, context:, source: nil)
         severity: severity,
         source: source
       }
-      if (record = SolidErrors::Error.find_by(error_attributes))
+      fingerprint = Digest::SHA256.hexdigest(error_attributes.values.join)
+      if (record = SolidErrors::Error.find_by(fingerprint: fingerprint))
         record.update!(resolved_at: nil, updated_at: Time.now)
       else
-        record = SolidErrors::Error.create!(error_attributes)
+        record = SolidErrors::Error.create!(error_attributes.merge(fingerprint: fingerprint))
       end
 
       SolidErrors::Occurrence.create(