Welcome to the DynamoDB Glossary. Here you will find definitions for common abbreviations and technical terms used throughout the course.

Example Usage: Hover over GSI to see the definition.

Core Concepts

Term Full Name Definition
Attribute Attribute A fundamental data element, something that does not need to be broken down any further. Analogous to a column in a relational database.
Composite Key Composite Primary Key A primary key composed of both a partition key and a sort key, allowing multiple items with the same partition key.
Consistent Hashing Consistent Hashing A technique used by DynamoDB to distribute data across partitions. It minimizes reorganization of data when nodes are added or removed.
Hash Key Hash Key (Partition Key) The first part of the primary key. DynamoDB uses the partition key’s value as input to an internal hash function. The output from the hash function determines the partition (physical storage internal to DynamoDB) in which the item is stored.
Hot Partition Hot Partition A partition that receives a disproportionate amount of read or write traffic, potentially leading to throttling if the traffic exceeds the partition’s throughput limits.
Item Item A collection of attributes. Each item is identifiable by a primary key. Items in DynamoDB are similar in many ways to rows, records, or tuples in other database systems.
On-Demand On-Demand Capacity A flexible billing option for DynamoDB capable of serving thousands of requests per second without capacity planning. You pay per request for the data reads and writes your application performs on your tables.
Partition Key Partition Key The primary key attribute used by DynamoDB to distribute data across partitions for scalability. Also known as the Hash Key.
Provisioned Mode Provisioned Mode A billing option where you specify the number of reads and writes per second that you require for your application. You can use auto-scaling to adjust your table’s provisioned capacity automatically in response to traffic changes.
Provisioned Throughput Provisioned Throughput The maximum amount of capacity (RCUs/WCUs) that an application can consume from a table or index.
RCU Read Capacity Unit One read capacity unit represents one strongly consistent read per second, or two eventually consistent reads per second, for an item up to 4 KB in size.
Sort Key Sort Key (Range Key) The second part of the primary key. If a table has a composite primary key (partition key and sort key), DynamoDB stores all the items with the same partition key value physically close together, sorted by the sort key value.
TTL Time To Live A mechanism that allows you to define a specific timestamp when an item is no longer needed. Shortly after the date and time of the specified timestamp, DynamoDB deletes the item from your table without consuming any write throughput.
WCU Write Capacity Unit One write capacity unit represents one write per second for an item up to 1 KB in size.

Indexes

Term Full Name Definition
GSI Global Secondary Index An index with a partition key and an optional sort key that can be different from those on the base table. GSIs allow you to query data across all partitions.
Item Collection Item Collection A group of items that share the same Partition Key but have different Sort Keys. Item collections allow related data to be retrieved in a single request using the Query operation.
LSI Local Secondary Index An index that has the same partition key as the base table but a different sort key. LSIs allow you to query data within a single partition using an alternative sort order.
Overloading Index Overloading A design pattern where a single GSI is used to index multiple different entity types by using generic key names (e.g., GSI1PK, GSI1SK).
Projection Index Projection The set of attributes that are copied (projected) from the base table into a secondary index.
Sparse Index Sparse Index An index that only contains items that have a value for the index’s sort key (or partition key). Items without the key are omitted.

Consistency & Operations

Term Full Name Definition
BatchWriteItem BatchWriteItem An operation that puts or deletes multiple items in one or more tables. It does not provide atomicity across items.
Conditional Write Conditional Write A write operation that succeeds only if the item attributes meet one or more expected conditions.
Condition Expression Condition Expression An expression used in PutItem, UpdateItem, or DeleteItem to specify conditions that must be met for the operation to succeed (optimistic locking).
Consistent Read Consistent Read A read operation that returns the most up-to-date data, reflecting all successful write operations that occurred before the read. Consumes 2x the capacity units of an eventually consistent read.
Eventual Consistency Eventual Consistency The default consistency model for DynamoDB read operations. When you read data from a DynamoDB table, the response might not reflect the results of a recently completed write operation.
Filter Expression Filter Expression An expression used in Query or Scan to filter the results after they have been read from the table but before they are returned to the client.
Query Query Operation An operation that finds items based on primary key values. Highly efficient compared to Scan.
Scan Scan Operation An operation that reads every item in a table or secondary index. Generally inefficient for large tables.
Strong Consistency Strong Consistency A read consistency model that guarantees that a read returns the most recent write.
Transaction TransactWriteItems An API operation that groups up to 100 actions into a single all-or-nothing operation with ACID properties.

Advanced Patterns

Term Full Name Definition
Access Pattern Access Pattern The specific query or operation an application needs to perform on the database. In DynamoDB, schema design begins with identifying all access patterns first, rather than modeling the data structure first.
Adaptive Capacity Adaptive Capacity A feature that automatically isolates frequently accessed items on a partition and re-balances them to other partitions to prevent hot partitions.
Adjacency List Adjacency List Pattern A design pattern used to model many-to-many relationships in DynamoDB. It involves storing each relationship as an individual item, allowing for efficient querying of related entities.
DAX DynamoDB Accelerator A fully managed, highly available, in-memory cache for DynamoDB that delivers up to a 10x performance improvement.
DynamoDB Streams DynamoDB Streams An optional feature that captures a time-ordered sequence of item-level modifications in a DynamoDB table and stores this information for up to 24 hours.
GSI Sharding GSI Sharding A technique where a GSI partition key is computed (e.g., Status_0, Status_1) to avoid hot partitions on low-cardinality attributes.
Single Table Design Single Table Design A design philosophy where multiple entity types (e.g., Users, Orders, Products) are stored in a single DynamoDB table. This optimizes for performance by enabling the retrieval of heterogeneous items in a single request.
Streams DynamoDB Streams A feature that captures a time-ordered sequence of item-level modifications in a DynamoDB table and stores this information for up to 24 hours.
Write Sharding Write Sharding A technique to distribute writes across multiple partitions when a single partition key becomes a hot spot. It involves appending a random suffix to the partition key.