software.amazon.awssdk.enhanced.dynamodb.extensions.AtomicCounterExtension
- All Implemented Interfaces:
DynamoDbEnhancedClientExtension
This extension enables atomic counter attributes to be changed in DynamoDb by creating instructions for modifying an existing value or setting a start value. The extension is loaded by default when you instantiate a
DynamoDbEnhancedClient and only needs to be added to the client if you are adding custom extensions to the client. To utilize atomic counters, first create a field in your model that will be used to store the counter. This class field should of type Long and you need to tag it as an atomic counter:
Every time a new update of the record is successfully written to the database, the counter will be updated automatically. By default, the counter starts at 0 and increments by 1 for each update. The tags provide the capability of adjusting the counter start and increment/decrement values such as described in DynamoDbAtomicCounter.
Example 1: Using a bean based table schema
@DynamoDbBean public class CounterRecord { @DynamoDbAtomicCounter(delta = 5, startValue = 10) public Long getCustomCounter() { return customCounter; } } Example 2: Using a static table schema
private static final StaticTableSchema<AtomicCounterItem> ITEM_MAPPER = StaticTableSchema.builder(AtomicCounterItem.class) .newItemSupplier(AtomicCounterItem::new) .addAttribute(Long.class, a -> a.name("defaultCounter") .getter(AtomicCounterItem::getDefaultCounter) .setter(AtomicCounterItem::setDefaultCounter) .addTag(StaticAttributeTags.atomicCounter())) .build(); NOTES:
- When using putItem, the counter will be reset to its start value.
- The extension will remove any existing occurrences of the atomic counter attributes from the record during an updateItem operation. Manually editing attributes marked as atomic counters will have NO EFFECT.
Method Details
