![]() ![]() All of the index items with this key are storedĪdjacent to each other for rapid retrieval. GameTitle partition key to locate the index itemsįor Meteor Blasters. Gaming data for a leaderboard application.ĭynamoDB accesses GameTitleIndex, using the DynamoDB can return the results in ascendingĬonsider the following data returned from a Query that requests That you want to use, the attributes to be returned in the query results, and any The query must specify the name of the base table and the name of the index You can use the Query operation to access one or more items in a The GetItem and BatchGetItem operations can't be You can retrieve items from a global secondary index using the Query and Scan Reading data from a Global Secondary Index The global secondary index would be of minimal size, but would stillīe available when needed for query activity. Writes or updates against the data in the table, consider projecting If your application needs to query a table infrequently, but must perform many If you need to access most of the non-key attributes on a frequent basis, youĬan project these attributes-or even the entire base table- into a The additional storage costsįor the global secondary index offset the cost of performing frequent table scans. If your application frequently accesses some non-key attributes, you shouldĬonsider projecting those attributes into a global secondary index. ![]() The less that it costs to store it, and the less your write costs are. ![]() If you need to access just a few attributes with the lowest possible latency,Ĭonsider projecting only those attributes into a global secondary index. To project these attributes from the base table into the global secondary index, as shown in this A more efficient way to support queries on this data would be Have to perform an additional query on the base table to fetch the wins and losses forĮach of the top scorers. GameTitle and TopScore in queries, it can't efficientlyĭetermine the highest ratio of wins vs. So while an application canĮfficiently determine the UserId of the top scorers for each game using In the previous diagram, GameTitleIndex has Because all of the table data is duplicated in the index, an ALL projection results in the largest possible secondary index. KEYS_ONLY option results in the smallest possible secondary index.ĭescribed in KEYS_ONLY, the secondary index will include other non-key attributes that youĪLL – The secondary index includes all of the attributes from the source table. Of the table partition key and sort key values, plus the index key values. KEYS_ONLY – Each item in the index consists only The following is some data that could represent this. To illustrate, suppose that a game named Comet Quest isĮspecially difficult, with many new users trying but failing to get a score above zero. However, the key values in a global secondary index do In a DynamoDB table, each key value must be unique. GameTitleIndex as shown in the previous diagram, the query could notĪccess any non-key attributes other than TopScore (although the keyĪttributes GameTitle and UserId would automatically be Queries cannot fetch attributes from the base table. The index, DynamoDB can retrieve these projected attributes efficiently. You can project other base table attributes into the index if you want. Other scalar types, document types, and set types are Of any top-level String, Number, or BinaryĪttributes from the base table. (partition key and sort key)-or vice versa. Simple primary key (partition key), and create a global secondary index with a composite primary key Key schema can be different from the base table schema. Set the ScanIndexForward parameter to false, the results are returned inĭescending order, so the highest score is returned first.Įvery global secondary index must have a partition key, and can have an optional sort key. The results are ordered by the sort key values, TopScore. Now you can query GameTitleIndex and easily obtain the scores for Meteorīlasters. ![]()
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