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README.md

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+# Batch Update
+
+Update multiple records with different values in an optimized number of queries.
+
+This differs from [activerecord-import](https://github.com/zdennis/activerecord-import) because the latter issues a `INSERT ... ON DUPLICATE KEY UPDATE` statement which re-inserts the record if it happens to have been deleted in a other thread.
+
+## Usage
+Include in your Gemfile: `gem 'batch_update'`
+
+```ruby
+cat1 = Cat.create!(name: 'Felix', birthday: '1990-03-13')
+cat2 = Cat.create!(name: 'Garfield', birthday: '1978-06-19')
+cat3 = Cat.create!(name: 'Daisy', birthday: '1970-01-01')
+
+cat1.birthday = '2024-01-01'
+cat2.birthday = '2024-06-06'
+cat3.birthday = '1900-01-01'
+
+Cat.batch_update([cat1, cat2, cat3]) # issues a single SQL query
+```
+
+## Advanced usage
+Specify which columns to update (all columns are included by default):
+```ruby
+cat1.name = 'Lilly'
+cat1.birthday = '2024-01-01'
+cat2.birthday = '2023-06-06'
+Cat.batch_update([cat1, cat2], columns: %i[birthday])
+```
+
+Ignore model validations (all validations run by default):
+```ruby
+cat1.name = ''
+cat2.name = ''
+Cat.batch_update([cat1, cat2], validate: false)
+```
+
+Specify a different batch size (100 by default):
+```
+Cat.batch_update(cats, batch_size: 1000)
+```
+
+## License
+MIT