In this lesson, we'll learn some basics around the Query operation including using Queries to: Before reading this section, you should understand DynamoDB expressions. In the next lesson, we'll talk about Scans which is a much blunter instrument than the Query call. DynamoDB allows for specification of secondary indexes to aid in this sort of query. You need to perform multiple Query operations to retrieve Thanks for letting us know we're doing a good The ideal way is to build the element we want to query into the RANGE key. Query does partition pruning + index access to retrieve a sorted range of items Scan reads all partitions, possibly in parallel, to retrieve all items Of course, the cost is different. (<>). You need If you don't know how to construct your Query and its attributes, head to our DynamoDB Query Builder which will generate code for you. Recall that in our RANGE key of OrderId, we formatted it as -. If This call will create a DynamoDB table called MyTable with composite primary key where attribute id is the Hash Key, and createdAt is the Range Key. capacity units consumed is the same whether you request all of the attributes (the I posted a question here. Query the Thread table for a particular ForumName Hash key in DynamoDB. In future lessons, we'll see other ways to enable more advanced queries, including with filters or by using global secondary indexes and local secondary indexes. DynamoDB Scan vs Query - Syntax Differences. You must specify the partition key name and value as an equality condition. I have attached an example query: import boto3 from boto3 import dynamodb from boto3.session import Session dynamodb_session = … Keep in mind that Query can return up to 1MB of data and you can also use FilterExpressions here to narrow the results on non-key attributes.. If you've got a moment, please tell us what we did right You can optionally provide a second condition for the sort key (if present). If you want to get just the count of Items that satisfy a Query, you can use the --select option to return that: In this lesson, we covered the basics of the Query API call. There are two different ways we can handle this further segmentation. provide a filter expression. The way to fetch multiple items by a primary key query (which sounds weird at first), is to specify the hash key and then a range on the range key. DynamoDB reads up to six items, and then returns only those that match the filter b, a < b A partition key value is always required to query a global secondary index. A Query operation gets the values of one or more items and their attributes by primary key (Query is only available for hash-and-range primary key tables). A Hash Key consists of a single attribute that uniquely identifies an item. Hash key is used to select the DynamoDB partition. as a not on Using a table's primary key is the most efficient way to retrieve Items and avoids using the slow Scan operation.. The key condition selects the partition key and, optionally, a sort key. I hope this article helped anyone who was struggling to figure out how to query DynamoDB by time range. KeyConditionExpression. with certain characters. In this case, These Key Expressions are very useful for enabling more specific query patterns, but note the limitations. parameter to true in the Query request. the valid settings for ReturnConsumedCapacity: NONE — No consumed capacity data is returned. Learn about secondary indexes with AWS DynamoDB. The partition key query can only be equals to (=). The following AWS Command Line Interface (AWS CLI) examples demonstrate the use of c. The following function is also supported: begins_with (a, requests, you could keep a running tally of both ScannedCount and (This is the A filter expression is applied after a Query finishes, but before the #v as a placeholder. (partition key), but this time return only the items with a given Data organization and planning for data retrieval are critical steps when designing a table. We've already used the --key-condition-expression option to indicate the HASH key we want to use with our Query. items within the Query results should be returned to you. Count for the items that were processed by that particular It does not have a sort key as part of its primary key. Now suppose that you add a filter expression to the Query. Note that I assert that first item is the report from 2017 and second one is from … ":username": { "S": "daffyduck" }, Views. For more information, see Query and Scan in the Amazon DynamoDB Developer Guide. The primary key can also consist of the partition key and sort key (RANGE), which is complementary to the partition. You can use the sort key to filter for a specific client (for example, where InvoiceNumber=121212-1 and ClientTransactionid begins with Client1). results. Count. A Query operation performs eventually consistent reads, by default. Filter expressions can use the same comparators, functions, and logical operators DynamoDB supports two types of primary keys, a Hash Key and a Hash and Range Key. the amount of data that is returned to an application. You must provide a specific HashKeyValue, and can narrow the scope of the query using comparison operators on the RangeKeyValue of the primary key. Let's see how we can satisfy the latter request using the Query API call. The Query result For example, if we wanted all Orders from 2017, we would make sure our OrderId was between "20170101" and "20180101": Our results return three Items rather than all four of Daffy's Orders: Daffy's fourth order was in 2016 so it did not satisfy our Key Expression. This is less efficient than Key Expressions but can still be helpful … Query returns all items with that partition key value. Is it possible to get that only record with the greatest range key? Type: Integer. the request. contains the following elements: ScannedCount — The number of items that matched the key attribute. That means you cannot do what you would call a full table scan in other databases. The arguments for --expression-attribute-values are stored in the I am having trouble using AWS Boto3 to query DynamoDB with a hash key and a range key at the same time using the recommend KeyConditionExpression. the documentation better. But you will not be able to build query with multiple range keys simultaneously because DynamoDB can only use one index at a time. attribute a begins with a particular DynamoDB, best way to query on RANGE key? Only then are the Query results sent back to the client. capacity it consumes. For this reason, the number Query request. You must specify the partition key name and value as an equality condition. KeyConditionExpression and any FilterExpression that might You can't have more than 2 fields as primary key in DynamoDB. In a simple words range + hash key = composite primary key CoreComponents of Dynamodb. To use the AWS Documentation, Javascript must be However, the primary (partition) key can include a second attribute, which is called a sort key. The Query API call allows for a --projection-expression option similar to the GetItem call we explored previously. The primary reason for that complexity is that you cannot query DynamoDB without the hash key. :sub) instead of actual values. It’s easy to start filling an Amazon DynamoDB table with data. For more information, see Expression Attribute Names in DynamoDB. DynamoDBを初めて触るにあたり、DynamoDBの特徴や設計思想をまとめたサイトはたくさんあったのですが、 クエリ(以下、「Query」)についてまとめたサイトが見当たらなかったため、備忘録としてまとめてみました。 of sorry we let you down. Range keys are used to sort the items in … These expressions use placeholders (such as :name and If you want to try these examples on your own, you’ll need to get the data that we’ll be querying with. default.). results. The following are units, as follows. Query can use KeyConditionExpression to retrieve one item with a given hash and range key value, or several items that have the same hash key value but different range key values Query operations consume read capacity DynamoDB offers the possibility to define so-called secondary indexes. A string that identifies one or more attributes to retrieve from the table. of items but also need to discard most of those items. character is a-z or A-Z and the second character (if present) ProjectionExpression. ":startdate": { "S": "20170101" }, capacity, regardless of whether a filter expression is present. that you want. Otherwise, the results are returned in order of UTF-8 bytes. A table is a collection of items, and each item is a collection of attributes.DynamoDB uses primary keys to uniquely identify each item in a table and secondary indexes to provide more querying flexibility. As a workaround you can create local secondary index for each field that you want to be a range key. DynamoDB does not allow indexed lookups on the range key only. b, a >= b DynamoDB provides similar functionality with its Query and Scan actions, which are described in Querying a Table and Scanning a Table. Query the Reply table for a particular Id (partition table or index. In a Query operation, DynamoDB retrieves placeholder. Values. ScannedCount and Count represent only a partial count of Starting with the OrderDate in our RANGE key allows us to query by order date using the expression syntax. A second way to handle this is with filtering based on non-key attributes. — true if a is greater than or equal to data. If an attribute name does It would be inefficient to store the different partition keys for each User's Orders and query those Items separately. To do this, set the Limit parameter to the maximum number of items I have a dynamoDB table which allows users to leave reviews on products. All of the other As a workaround you can create local secondary index for each field that you want to be a range key. However, without forethought about organizing your data, you can limit your data-retrieval options later. Querying is a very powerful operation in DynamoDB. To specify the search criteria, you use a key condition expression—a string that determines the items to be read from the table or index. If the data type We're usually manipulating a single User at a time, whether retrieving a User's profile or changing a User's name. I think it's the most powerful part of DynamoDB, but it requires careful data modeling to get full value. order — true if the attribute a is equal to the value the total items. You can of course perform a scan operation to filter by the date value, however this would require a full table scan, so it is not ideal. A filter expression determines which the query because the sort key (Subject) is not included in You now add the index name to the API call. If the size of the Query result set is larger than 1 MB, Of TOTAL — The response includes the aggregate number of read In addition, the attribute I want to query DynamoDB table by hash and range key, using AWS SDK for Ruby V2. be present. You can also use Query Code Generation feature inside Dynobase.. Query with Sorting ":enddate": { "S": "20180101" } If no matching items are To reverse the order, set the ScanIndexForward parameter to The index is available to query after all items have been backfilled. A single Query operation can retrieve a maximum of 1 MB of The following AWS CLI example queries the Thread table for a particular This is less efficient than Key Expressions but can still be helpful in the right situations. For items with a given partition key value, DynamoDB stores these items close together, When I query it is returning, all the records with the specified hash key, reverse sorted by range key. browser. This combination gives us a good spread through the partitions. condition expression, with the addition of the not-equals operator To specify the search criteria, you use a key condition not meet these requirements, you must define an expression attribute name as a The sort key condition must use one of the following comparison operators: The following function is also supported:The following AWS Command Line Interface (AWS CLI) examples demonstrate the use of ke… specify those attributes in the key condition expression, not the filter If you require strongly consistent reads, set the ConsistentRead a is greater than or equal to Values. Without proper data organization, the only options for retrieving data are retrieval by partition key or […] On an Orders overview page, we could show all of a User's Orders with the ability to drill into a particular Order if the User desired. A Query operation always returns a result set. Users can also create up to five global secondary indexes with either a hash key or a hash key and a range key using attributes other than the item’s primary key. false. Optionally, Query the Thread table for a particular ForumName In DynamoDB, tables, items, and attributes are the core components that you work with. DynamoDB calculates the number of read capacity units consumed based on item size, ":username": { "S": "daffyduck" } With larger Items, it can increase your response size in undesirable ways. expression. values.json file. A second way to handle this is with filtering based on non-key attributes. So, it’s not allowed to query the entire database. With simple key, DynamoDB essentially works just like a Key-Value store. The base table's provisioned read capacity. enabled. This b, a > b But you will not be able to build query with multiple range keys simultaneously because DynamoDB can only use one index at … This limit applies before any FilterExpression is applied to the key condition must use one of the following comparison operators: a = b returned—in other words, only those threads with more than a certain number of Thus, if you want a compound primary key, then add a sort key so you can use other operators than strict equality. You can get an item using its Id value. When you add a global secondary index to an existing table, DynamoDB asynchronously backfills the index with the existing items in the table. b, a <= b Secondary indexes can either be global, meaning that the index spans the whole table across hash keys, or local meaning that the index would exist within each hash key partition, thus requiring the hash key to also be specified when making the query. We knew we will get single item. The condition can also perform one of several comparison tests on a single range key value. DynamoDB stores items with the same partition key physically close together, in sorted order by the sort key value. capacity units consumed. You can use the sort key to filter for a specific client (for example, where InvoiceNumber=121212-1 and ClientTransactionid begins with Client1). b. a BETWEEN b AND Because the Key Expression can only operate on the HASH and RANGE key, you need to build the relevant data into the keys directly. And I request a sort on the RANGE key which is locally indexed in DynamoDB, and then can scan the items in this order. Note that Views is a reserved word in DynamoDB (see Reserved Words in DynamoDB), so this example uses also the same whether or not you use a filter expression. When you define a key schema, you specify which attributes to use for a key, and their data types. This allows you to limit the Items to return just the attributes you care about. b, and less than or equal to the items that are found, only the most popular discussion threads are Global secondary indexes use the value of the partition key as input to an internal hash function, which is similar to how a partition key is used in a DynamoDB table. To obtain grand totals for all of the Query It specifies the condition that the key values for items to be retrieved by this action. The example table uses a String hash key (Artist), a String range key (SongTitle), and a local secondary index on the AlbumTitle attribute (also a String). Note the following about the Musictable: For more information, see Working with Tables and Data in DynamoDB. results are discarded. }', "Username = :username AND OrderId BETWEEN :startdate AND :enddate", '{ For example, if we just wanted to return the Amounts for Daffy's Orders, we could pass a projection expression accordingly: And the response contains only the Amount: Note that both responses so far have included a "Count" key that shows how many Items were returned in the response. You lose the ability to perform a Query , to fetch data from a table with such key, you can use Scan or GetItem operation. condition expression before a filter Following code can work. 概要. In the first query we used dynamodbattribute.UnmarshalMap for unmarshaling single DynamoDB item into the struct. You can use any attribute name in a key condition expression, provided that the first The hash key is required such that the service knows which partition to look in to find the data. The syntax for a filter expression is identical to that of a condition expression. Example: Handling Binary Type Attributes - .NET Low-Level API, Limiting the Number of Items in the Result Set, Expression Attribute If … The DynamoDB Book is a comprehensive guide to modeling your DynamoDB tables, Learn the how, what, and why to DynamoDB modeling with real examples, '{ A filter expression removes items from the Query result set. substring. We're found, the result set is empty. }', retrieve all Items with a given partition key. This combination gives us a good spread through the partitions. Further, it limits the number of query patterns you can enable. The following are the basic DynamoDB components: The following diagram shows a table named Peoplewith some example items and attributes. The only difference is KeyConditionExpression parameter which is required in Query operation. DynamoDB Query Rules. ; Because we have a random number appended to our partition key (1–5), we need to query the table five times for a given InvoiceNumber.Our partition key … items. Yes , set the "limit" parameter to 1: "The DynamoDB Query and Scan APIs allow a Limit value to restrict the size of the results." You can't have more than 2 fields as primary key in DynamoDB. Javascript is disabled or is unavailable in your default behavior) or just some of them (using a projection expression). If you don't use a filter expression, ScannedCount and Query results are always sorted by the sort key value. The partition key query can only be equals to (=). Occasionally we want to grab a specific Order, but we also may want to display all the Orders for a particular User. When querying to return Items, you might want to further limit the Items returned rather than returning all Items with a particular HASH key. Please refer to your browser's Help pages for instructions. However, the requirement of using a primary key limits the access patterns of a table. (For a complete list of these, see Reserved Words in DynamoDB.) The number Each Query response contains the ScannedCount and Count have the same value. index that was accessed. By default, a Query operation does not return any data on how much read Therefore, a Query consumes the same amount of read — true if a is less than The engine is DynamoDB and PartiQL maps a SQL-like language on top of the DynamoDB NoSQL API. A filter expression cannot contain partition key or sort key attributes. If LastEvaluatedKey is present in the response and is non-null, It means that items with the same id will be assigned to the same partition, and they will be sorted on the date of their creation. The way to fetch multiple items by a primary key query (which sounds weird at first), is to specify the hash key and then a range on the range key. The Reply table's primary key is composed of Id and ReplyDateTime attributes. Choosing this option allows items to share the same partition/hash key, but the combination of hash key and sort key must be unique. Choosing to start your RANGE key with the OrderDate means you can't do a Key Expression based on the Amount of the Order. you can provide a sort key attribute and use a comparison operator to refine the search When updating a model the hash and range key attributes must be given, all other attributes are optional ... For models that use hash and range keys DynamoDB provides a flexible and chainable query api ... Query Filters allow you to further filter results on non-key attributes. applied. Required: No. is a-z, A-Z, or 0-9. In a moment, we’ll load this data into the DynamoDB table we’re about to create. DynamoDB Composite Key capacity units consumed, together with the consumed capacity for each table and It's not so bad in our example above with small Items. The key condition selects the partition key and, optionally, a sort key. It allows you to select multiple Items that have the same partition ("HASH") key but different sort ("RANGE") keys. In addition to the items that match your criteria, the Query response more items would have matched the filter expression if DynamoDB had kept reading more With a composite key, you gain the ability to use queries with a KeyConditionExpression against the sort key. For more INDEXES — The response shows the aggregate number of read So, it’s not allowed to query the entire database. you must paginate the result set (see Paginating Table Query Results). That means you cannot do what you would call a full table scan in other databases. DynamoDB Composite Key Another option is to use a composite key, which is composed of partition key, also known as hash key, and sort key, also known as range key. Using a secondary index to query a table is similar to using the Query API call. This allows us to use Key Expressions to query our data, allowing DynamoDB to quickly find the Items that satisfy our Query. In a query, you can use KeyConditionExpression to write conditional statements by using comparison operators that evaluate against a key and limit the items returned. We can also include a RANGE key value or an expression to operate on that RANGE key. value of 6, and without a filter expression. — true if a is greater than Description. expression—a string that determines the items to be read from the The output value from the hash function determines the partition in which the item is stored. expression. I am having trouble using AWS Boto3 to query DynamoDB with a hash key and a range key at the same time using the recommend KeyConditionExpression. It returns with all four of Daffy's Orders: This is really useful. For example, when designing our table, we decided we wanted to answer the query: Give me all of the OrderIds for a particular Username. Partitions are parts of the table data. With the DynamoDB API you know which one you are doing because you call a different operation. — true if a is less than or equal to For more information, see Condition Expressions. That can be useful in some scenarios, such as working with Users. job! For more information, see Expression Attribute Names in DynamoDB and Expression Attribute You can copy or download my sample data and save it locally somewhere as data.json. of the sort key is Number, the results are returned in numeric order. For more information, see Expression Attribute Names in DynamoDB. You can Query any table or secondary index, provided that it has a composite primary By default, the sort The final Query result contains six items or fewer, even if key (partition key and sort key). Moreover, we're specifying --provisioned-throughput argument which will create a table in provisioned … This allows us to use Key Expressions to query our data, allowing DynamoDB to quickly find the Items that satisfy our Query. There are two different ways we can handle this further segmentation. The primary reason for that complexity is that you cannot query DynamoDB without the hash key. Request parameters for both Query and Scan are almost identical. all the results (see Paginating Table Query Results). Up to this point, most read operations have used a table's primary key directly, either through the GetItem call or the Query call. It’s as if your key is split in two. expressions. parameter in a Query request to obtain this information. In the responses above, the Query result is returning full Item that satisfies our Query request. : name and value as an equality condition planning for data retrieval critical... Further refine the search results Key-Value store consume read capacity units consumed attributes to retrieve items and attributes refine. 'Re usually manipulating a single Query operation allows you to limit the items to share the same value partition which... Dynamodb composite key you ca n't have more than 2 fields as primary key ( if present ) equality on. Orderdate means you can create local secondary index to an existing table, DynamoDB works... Changing a User 's Orders: this is less efficient than key Expressions are useful. The access patterns of a table, DynamoDB essentially works just like a Key-Value store are. Must be unique display all the results are returned Low-Level API, Limiting number. Not contain partition key or sort key is split in two select statement perform. Table is similar to using the Query requests, you must paginate the result.. Call allows for a -- projection-expression option similar to using the expression syntax a simple range. List of these, see working with Users unavailable in your browser 's Help pages for instructions reads to... Which attributes to use the AWS Documentation, javascript must be enabled words range + hash key and sort (... Key condition and filter expression you must provide the name of the sort to! Not a database engine: sub ) instead of actual values spread through the partitions in the values.json.. Partition keys for each field that you can copy or download my sample and. Condition must perform an equality condition key and an optional range key this. Just the attributes you care about up to six items from the Query API call there are two different we... 'S Orders and Query those items separately information, see reserved words in DynamoDB the! Of whether a filter expression or [ … on that range key value actions, is. Our data, allowing DynamoDB to quickly find the data of its primary key limits access. Our daffyduck User thus, if you do n't use a comparison operator refine... Sort the items that remain after a filter expression you can specify the partition key and a hash key your. Key Expressions are very useful for enabling more specific Query patterns, but note the AWS. Key limits the number of dynamodb range key query capacity, regardless of whether a filter expression see reserved in... Key physically close together, in sorted order by the sort key is split in.... Such that the Query requests dynamodb range key query you can specify the partition key ) and Subject ( sort.... Perform multiple Query operations to retrieve items and attributes Query any table or secondary index define an expression Names! Chapter, we ’ re about to create not do what you would a. Identical to that of a condition expression data is returned did right so we can do of! Now suppose that you can not do what you would call a full table Scan in situations. Putitem or UpdateItem operations DynamoDB to quickly find the items that satisfy our Query this page needs work example and! Starting with the same whether or not you use a filter expression Interface ( AWS CLI examples... Ideal way is to build the element we want to use the sort key is the important thing view... Back to the partition key ) and Subject ( sort key 1 MB of.... An equality condition dynamodb range key query the same Amount of read capacity, regardless whether... Full item that satisfies our Query filling an Amazon DynamoDB Developer Guide Scanning a is... Requires careful data modeling to get full value organization, the result set ( see Paginating Query... 'S the most powerful part of DynamoDB. further segmentation Querying a table 's key..., regardless of whether a filter expression removes items from the table the DynamoDB API know... You use a filter expression is evaluated different ways we can do more of it can specify partition. That the key condition selects the partition key attribute and use a filter is! Id and ReplyDateTime attributes range keys simultaneously because DynamoDB can only use one index at time. A condition expression from the request a global secondary index to an existing table, DynamoDB works. Key-Value store and data in DynamoDB. values for items with the DynamoDB you... Returning full item that satisfies our Query in to find the data type of the results... Partition keys for each field that you Query a table named Peoplewith some example and... Re about to create Expressions use placeholders ( such asÂ: name and value as equality. についてまとめたサイトが見当たらなかったため、備忘録としてまとめてみました。 using a table named Peoplewith some example items and avoids using the Query can. With all four of Daffy 's Orders and Query those items separately see how to use queries with KeyConditionExpression. Developer Guide condition must perform an equality condition Id and ReplyDateTime attributes this information start filling Amazon! Request parameters for both Query and Scan are almost identical of several comparison tests on a single that... Requirements, you could keep a running tally of both ScannedCount and Count the... Data and save it locally somewhere as data.json be returned to you DynamoDB can only be equals (! Default, a hash and range key to filter for a particular User blunter instrument than the Query a. Is empty multiple Query operations to retrieve from the Query requests, you enable. In other databases data modeling to get that only record with the OrderDate in our example above small! A DynamoDB table with data must keep in mind that PartiQL is not a engine! Also perform one of several comparison tests on a single range key allows us to Query our data, must... Of the Query operation with Orders top of the Orders for a complete list of,. Can make the Documentation better, with a KeyConditionExpression against the sort key must unique! Thus, if you want to Query the entire database one of comparison... Your key is the important thing to view here -- key-condition-expression option to indicate the hash key we to. Slow Scan operation: this is with filtering based on non-key attributes it returning! Ideal way is to build Query with multiple range keys are used to select and begins! Data types results might not reflect changes due to recently completed PutItem or UpdateItem operations talk... Table we ’ re about to create attribute values right situations for more information, see attribute! Disabled or is unavailable in your browser that in our previous chapter, we 'll retrieve all of the key. Equality test on a single User at a time range ), which is much! Filterexpression is applied to the results ( see Paginating table Query results ) has a composite primary key can a. Querying a table, DynamoDB asynchronously backfills the index is available to Query our data, allowing you retrieve... Expression removes items from the Query includes a key, and then returns only that. You require strongly consistent reads, set the limit parameter to the GetItem call we explored previously partition. A User 's profile or changing a User 's Orders and Query those items separately ’ re to! A hash key consists of a table reviews on products to specify those attributes in key... List of these, see Query and Scan are almost identical result the. A SQL-like language on top of the Orders for dynamodb range key query particular Username where the Amount was than. In a Query consumes the same partition key name and: sub ) instead of actual.! Select the DynamoDB table with data in Query operation performs eventually consistent reads, set the parameter! Getitem call we explored previously allows items to be retrieved by this action value or an expression to on... Complete list of these, see expression attribute Names in DynamoDB: the Query a! Returns all items have been backfilled index for each User 's profile or changing a User 's or... To an existing table, with a composite primary key in DynamoDB. together, in sorted by. Table for a particular User InvoiceNumber=121212-1 and ClientTransactionid begins with Client1 ) results see. Us to use key Expressions to Query after all items with a limit value of 6, then... Is consists of a table, with a given partition key and,,. About the Musictable: for more information, see Query and Scan are almost identical ReturnConsumedCapacity parameter in a,... Sort key attribute and a single value for that complexity is that you optionally! Than $ 50 set the ConsistentRead parameter to false is not a database engine filtering based on non-key.. Expressions use placeholders ( such asÂ: name dynamodb range key query value as an condition. ’ ll load this data into the range key value did right so we can handle this is less than! Not allow indexed lookups on the range key as < OrderDate > - < RandomInteger > results! Database engine used the -- key-condition-expression option to indicate the hash key is used select... Table Scan in other situations, such as working with Tables and data in DynamoDB. and ReplyDateTime.... Results are returned, and their data types key so you can use the AWS Documentation, javascript must unique... This data into the DynamoDB API you know which one you are doing because you call a table! Specifies the condition can also consist of the DynamoDB NoSQL API allows us to queries. The engine is DynamoDB and PartiQL maps a SQL-like language on top the! Provide a sort key more specific Query patterns you can create local index. A time 're doing a good spread through the partitions n't have more than 2 fields as primary key DynamoDB!