d3882df437
When we insert a record in PostgreSQL and we specify the ID, the internal ID sequence for that table isn't updated. In order to keep the original IDs so we didn't break any foreign keys, we specified the IDs when copying the table, resulting in a table having its ID sequence with a value of an existing record. When trying to insert a new record, we got a `PG::UniqueViolation` exception. Updating the sequence after the data migration might not be the most elegant solution, but it's easy to do and it's already been tested on a production environment.
107 lines
4.2 KiB
Ruby
107 lines
4.2 KiB
Ruby
namespace :milestones do
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def generate_table_migration_sql(new_table:, old_table:, columns:)
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from_cols = ['id', *columns.keys]
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to_cols = ['id', *columns.values]
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<<~SQL
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INSERT INTO #{new_table} (#{to_cols.join(', ')})
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SELECT #{from_cols.join(', ')} FROM #{old_table};
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SQL
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end
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def migrate_table!(new_table:, old_table:, columns:)
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puts "Migrating data from '#{old_table}' to '#{new_table}'..."
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result = ActiveRecord::Base.connection.execute(
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generate_table_migration_sql(old_table: old_table,
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new_table: new_table,
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columns: columns)
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)
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puts "#{result.cmd_tuples} rows affected"
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end
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def populate_column!(table:, column:, value:)
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puts "Populating column '#{column}' from table '#{table}' with '#{value}'..."
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result = ActiveRecord::Base.connection.execute(
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"UPDATE #{table} SET #{column} = '#{value}';"
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)
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puts "#{result.cmd_tuples} rows affected"
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end
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def count_rows(table)
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ActiveRecord::Base.connection.query("SELECT COUNT(*) FROM #{table};")[0][0].to_i
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end
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desc "Migrate milestones and milestone status data after making the model polymorphic"
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task migrate: :environment do
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# This script copies all milestone-related data from the old tables to
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# the new ones (preserving all primary keys). All 3 of the new tables
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# must be empty.
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#
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# To clear the new tables to test this script:
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#
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# DELETE FROM milestone_statuses;
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# DELETE FROM milestones;
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# DELETE FROM milestone_translations;
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#
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start = Time.now
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ActiveRecord::Base.transaction do
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migrate_table! old_table: 'budget_investment_statuses',
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new_table: 'milestone_statuses',
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columns: {'name' => 'name',
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'description' => 'description',
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'hidden_at' => 'hidden_at',
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'created_at' => 'created_at',
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'updated_at' => 'updated_at'}
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migrate_table! old_table: 'budget_investment_milestones',
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new_table: 'milestones',
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columns: {'investment_id' => 'milestoneable_id',
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'title' => 'title',
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'description' => 'description',
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'created_at' => 'created_at',
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'updated_at' => 'updated_at',
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'publication_date' => 'publication_date',
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'status_id' => 'status_id'}
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populate_column! table: 'milestones',
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column: 'milestoneable_type',
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value: 'Budget::Investment'
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migrate_table! old_table: 'budget_investment_milestone_translations',
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new_table: 'milestone_translations',
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columns: {'budget_investment_milestone_id' => 'milestone_id',
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'locale' => 'locale',
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'created_at' => 'created_at',
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'updated_at' => 'updated_at',
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'title' => 'title',
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'description' => 'description'}
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Image.where(imageable_type: "Budget::Investment::Milestone").
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update_all(imageable_type: "Milestone")
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Document.where(documentable_type: "Budget::Investment::Milestone").
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update_all(documentable_type: "Milestone")
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puts "Verifying that all rows were copied..."
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{
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"budget_investment_milestones" => "milestones",
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"budget_investment_statuses" => "milestone_statuses",
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"budget_investment_milestone_translations" => "milestone_translations"
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}.each do |original_table, migrated_table|
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ActiveRecord::Base.connection.execute(
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"select setval('#{migrated_table}_id_seq', (select max(id) from #{migrated_table}));"
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)
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unless count_rows(original_table) == count_rows(migrated_table)
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raise "Number of rows of old and new tables do not match! Rolling back transaction..."
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end
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end
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end
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puts "Finished in %.3f seconds" % (Time.now - start)
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end
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end
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