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RanVakninRanVaknin
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DDB Enhanced: Allow custom versioning (#6019)
* Adding annotation support * Making annotation values nullable to know if initial value is explicitly set * Added changelog with attribution * Fix checkstyle * Adding japicmp excludes block * Adding additional test coverage to account for all isInitialVersion codepaths * Removing logger config file * porting version from Integer to Long, removing refactoring * refactoring and adding test coverage * adding annotation test * adding localstack test, removing optional from function signature * fix checkstyle * Adding overflow protection * Fixed edge case in isInitialVersion, fixed javadoc and typos --------- Co-authored-by: Ran Vaknin <[email protected]>
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‎.changes/next-release/feature-DynamoDBEnhancedClient-2a501d8.json

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{
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"type": "feature",
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"category": "DynamoDB Enhanced Client",
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"contributor": "akiesler",
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"description": "Support for Version Starting at 0 with Configurable Increment"
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}

‎pom.xml

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<includeModule>polly</includeModule>
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</includeModules>
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<excludes>
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<!-- TODO remove after release -->
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<exclude>software.amazon.awssdk.enhanced.dynamodb.extensions.annotations.DynamoDbVersionAttribute#incrementBy()</exclude>
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<exclude>software.amazon.awssdk.enhanced.dynamodb.extensions.annotations.DynamoDbVersionAttribute#startAt()</exclude>
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<exclude>*.internal.*</exclude>
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<exclude>software.amazon.awssdk.thirdparty.*</exclude>
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<exclude>software.amazon.awssdk.regions.*</exclude>

‎services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/Expression.java

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import software.amazon.awssdk.annotations.SdkPublicApi;
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import software.amazon.awssdk.annotations.ThreadSafe;
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import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
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import software.amazon.awssdk.utils.ToString;
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/**
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* High-level representation of a DynamoDB 'expression' that can be used in various situations where the API requires
@@ -311,6 +312,15 @@ public int hashCode() {
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return result;
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}
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@Override
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public String toString() {
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return ToString.builder("Expression")
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.add("expression", expression)
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.add("expressionValues", expressionValues)
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.add("expressionNames", expressionNames)
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.build();
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}
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/**
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* A builder for {@link Expression}
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*/

‎services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/extensions/VersionedRecordExtension.java

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@@ -34,6 +34,7 @@
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import software.amazon.awssdk.enhanced.dynamodb.mapper.StaticAttributeTag;
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import software.amazon.awssdk.enhanced.dynamodb.mapper.StaticTableMetadata;
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import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
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import software.amazon.awssdk.utils.Validate;
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/**
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* This extension implements optimistic locking on record writes by means of a 'record version number' that is used
@@ -61,7 +62,18 @@ public final class VersionedRecordExtension implements DynamoDbEnhancedClientExt
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private static final String CUSTOM_METADATA_KEY = "VersionedRecordExtension:VersionAttribute";
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private static final VersionAttribute VERSION_ATTRIBUTE = new VersionAttribute();
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private VersionedRecordExtension() {
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private final long startAt;
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private final long incrementBy;
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private VersionedRecordExtension(Long startAt, Long incrementBy) {
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Validate.isNotNegativeOrNull(startAt, "startAt");
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if (incrementBy != null && incrementBy < 1) {
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throw new IllegalArgumentException("incrementBy must be greater than 0.");
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}
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this.startAt = startAt != null ? startAt : 0L;
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this.incrementBy = incrementBy != null ? incrementBy : 1L;
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}
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public static Builder builder() {
@@ -75,19 +87,47 @@ private AttributeTags() {
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public static StaticAttributeTag versionAttribute() {
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return VERSION_ATTRIBUTE;
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}
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public static StaticAttributeTag versionAttribute(Long startAt, Long incrementBy) {
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return new VersionAttribute(startAt, incrementBy);
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}
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}
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private static class VersionAttribute implements StaticAttributeTag {
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private static final class VersionAttribute implements StaticAttributeTag {
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private static final String START_AT_METADATA_KEY = "VersionedRecordExtension:StartAt";
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private static final String INCREMENT_BY_METADATA_KEY = "VersionedRecordExtension:IncrementBy";
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private final Long startAt;
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private final Long incrementBy;
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private VersionAttribute() {
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this.startAt = null;
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this.incrementBy = null;
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}
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private VersionAttribute(Long startAt, Long incrementBy) {
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this.startAt = startAt;
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this.incrementBy = incrementBy;
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}
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@Override
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public Consumer<StaticTableMetadata.Builder> modifyMetadata(String attributeName,
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AttributeValueType attributeValueType) {
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if (attributeValueType != AttributeValueType.N) {
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throw new IllegalArgumentException(String.format(
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"Attribute '%s' of type %s is not a suitable type to be used as a version attribute. Only type 'N' " +
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"is supported.", attributeName, attributeValueType.name()));
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"is supported.", attributeName, attributeValueType.name()));
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}
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Validate.isNotNegativeOrNull(startAt, "startAt");
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if (incrementBy != null && incrementBy < 1) {
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throw new IllegalArgumentException("incrementBy must be greater than 0.");
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}
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return metadata -> metadata.addCustomMetadataObject(CUSTOM_METADATA_KEY, attributeName)
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.addCustomMetadataObject(START_AT_METADATA_KEY, startAt)
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.addCustomMetadataObject(INCREMENT_BY_METADATA_KEY, incrementBy)
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.markAttributeAsKey(attributeName, attributeValueType);
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}
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}
@@ -106,31 +146,53 @@ public WriteModification beforeWrite(DynamoDbExtensionContext.BeforeWrite contex
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String attributeKeyRef = keyRef(versionAttributeKey.get());
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AttributeValue newVersionValue;
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Expression condition;
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Optional<AttributeValue> existingVersionValue =
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Optional.ofNullable(itemToTransform.get(versionAttributeKey.get()));
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if (!existingVersionValue.isPresent() || isNullAttributeValue(existingVersionValue.get())) {
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// First version of the record
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newVersionValue = AttributeValue.builder().n("1").build();
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AttributeValue existingVersionValue = itemToTransform.get(versionAttributeKey.get());
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Long versionStartAtFromAnnotation = context.tableMetadata()
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.customMetadataObject(VersionAttribute.START_AT_METADATA_KEY, Long.class)
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.orElse(this.startAt);
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Long versionIncrementByFromAnnotation = context.tableMetadata()
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.customMetadataObject(VersionAttribute.INCREMENT_BY_METADATA_KEY, Long.class)
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.orElse(this.incrementBy);
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if (isInitialVersion(existingVersionValue, versionStartAtFromAnnotation)) {
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newVersionValue = AttributeValue.builder()
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.n(Long.toString(versionStartAtFromAnnotation + versionIncrementByFromAnnotation))
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.build();
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condition = Expression.builder()
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.expression(String.format("attribute_not_exists(%s)", attributeKeyRef))
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.expressionNames(Collections.singletonMap(attributeKeyRef, versionAttributeKey.get()))
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.build();
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} else {
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// Existing record, increment version
121-
if (existingVersionValue.get().n() == null) {
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if (existingVersionValue.n() == null) {
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// In this case a non-null version attribute is present, but it's not an N
123171
throw new IllegalArgumentException("Version attribute appears to be the wrong type. N is required.");
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}
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126-
int existingVersion = Integer.parseInt(existingVersionValue.get().n());
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long existingVersion = Long.parseLong(existingVersionValue.n());
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String existingVersionValueKey = VERSIONED_RECORD_EXPRESSION_VALUE_KEY_MAPPER.apply(versionAttributeKey.get());
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newVersionValue = AttributeValue.builder().n(Integer.toString(existingVersion + 1)).build();
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long increment = versionIncrementByFromAnnotation;
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/*
180+
Since the new incrementBy and StartAt functionality can now accept any positive number, though unlikely
181+
to happen in a real life scenario, we should add overflow protection.
182+
*/
183+
if (existingVersion > Long.MAX_VALUE - increment) {
184+
throw new IllegalStateException(
185+
String.format("Version overflow detected. Current version %d + increment %d would exceed Long.MAX_VALUE",
186+
existingVersion, increment));
187+
}
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189+
newVersionValue = AttributeValue.builder().n(Long.toString(existingVersion + increment)).build();
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129191
condition = Expression.builder()
130192
.expression(String.format("%s = %s", attributeKeyRef, existingVersionValueKey))
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.expressionNames(Collections.singletonMap(attributeKeyRef, versionAttributeKey.get()))
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.expressionValues(Collections.singletonMap(existingVersionValueKey,
133-
existingVersionValue.get()))
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existingVersionValue))
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.build();
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}
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@@ -142,13 +204,55 @@ public WriteModification beforeWrite(DynamoDbExtensionContext.BeforeWrite contex
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.build();
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}
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207+
private boolean isInitialVersion(AttributeValue existingVersionValue, Long versionStartAtFromAnnotation) {
208+
if (existingVersionValue == null || isNullAttributeValue(existingVersionValue)) {
209+
return true;
210+
}
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212+
if (existingVersionValue.n() != null) {
213+
long currentVersion = Long.parseLong(existingVersionValue.n());
214+
// If annotation value is present, use it, otherwise fall back to the extension's value
215+
Long effectiveStartAt = versionStartAtFromAnnotation != null ? versionStartAtFromAnnotation : this.startAt;
216+
return currentVersion == effectiveStartAt;
217+
}
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219+
return false;
220+
}
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@NotThreadSafe
146223
public static final class Builder {
224+
private Long startAt;
225+
private Long incrementBy;
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147227
private Builder() {
148228
}
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230+
/**
231+
* Sets the startAt used to compare if a record is the initial version of a record.
232+
* Default value - {@code 0}.
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*
234+
* @param startAt the starting value for version comparison, must not be negative
235+
* @return the builder instance
236+
*/
237+
public Builder startAt(Long startAt) {
238+
this.startAt = startAt;
239+
return this;
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}
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242+
/**
243+
* Sets the amount to increment the version by with each subsequent update.
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* Default value - {@code 1}.
245+
*
246+
* @param incrementBy the amount to increment the version by, must be greater than 0
247+
* @return the builder instance
248+
*/
249+
public Builder incrementBy(Long incrementBy) {
250+
this.incrementBy = incrementBy;
251+
return this;
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}
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150254
public VersionedRecordExtension build() {
151-
return new VersionedRecordExtension();
255+
return new VersionedRecordExtension(this.startAt, this.incrementBy);
152256
}
153257
}
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}

‎services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/extensions/annotations/DynamoDbVersionAttribute.java

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@Retention(RetentionPolicy.RUNTIME)
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@BeanTableSchemaAttributeTag(VersionRecordAttributeTags.class)
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public @interface DynamoDbVersionAttribute {
36+
/**
37+
* The starting value for the version attribute.
38+
* Default value - {@code 0}.
39+
*
40+
* @return the starting value
41+
*/
42+
long startAt() default 0;
43+
44+
/**
45+
* The amount to increment the version by with each update.
46+
* Default value - {@code 1}.
47+
*
48+
* @return the increment value
49+
*/
50+
long incrementBy() default 1;
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}

‎services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/extensions/VersionRecordAttributeTags.java

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@@ -26,6 +26,6 @@ private VersionRecordAttributeTags() {
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}
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public static StaticAttributeTag attributeTagFor(DynamoDbVersionAttribute annotation) {
29-
return VersionedRecordExtension.AttributeTags.versionAttribute();
29+
return VersionedRecordExtension.AttributeTags.versionAttribute(annotation.startAt(), annotation.incrementBy());
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}
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}

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