Difference between local and global indexes in DynamoDB

Question

I\'m curious about these two secondary indexes and differences between them. It is hard to imagine how this looks like. And I think, this will help more people than just me.

Answer 1

These are the possible searches by index:

• By Hash
• By Hash + Range
• By Hash + Local Index
• By Global index
• By Global index + Range Index

Hash and Range indexes of a table: These are the usual indexes of previous versions of the Amazon AWS SDK.

Global and Local indexes: These are 'additional' indexes created on a table, in addition to existing hash and range indexes of the table. Global index is similar to a hash. Range index behave similarly to the range index used with the hash of the table. In you entity model in your code, the getter must be annotated in this way:

• For global indexes:

  @DynamoDBIndexHashKey(globalSecondaryIndexName = INDEX_GLOBAL_RANGE_US_TS)
  @DynamoDBAttribute(attributeName = PROPERTY_USER)
  public String getUser() {
      return user;
  }
  

• For range index associated to the global index:

  @DynamoDBIndexRangeKey(globalSecondaryIndexName = INDEX_GLOBAL_RANGE_US_TS)
  @DynamoDBAttribute(attributeName = PROPERTY_TIMESTAMP)
  public String getTimestamp() {
      return timestamp;
  }
  

Besides, if you read a table by a Global index, it must be an Eventual read (not Consistent read):

queryExpression.setConsistentRead(false);