The Hash Key is the status of a project (ie: new, assigned, processing, or complete). You would have to query by Hash Key with the EQ operator and then narrow the results with the Filter Expression. In this article we will look at how to Read / Write Amazon DynamoDB in SSIS. Remember: each item in a table is uniquely identified by a primary key, even with the composite key. A Transaction groups multiple operations so that either all of them fail or all of them succeed together. a simple object mapper - use object notation to work with dynamo records. passionate about MongoDB, Node, Java, C#, Python, and Django. What is the key-value store? Answer: Key-value store is a database service which facilitates the storing, updating, and querying of the objects which are generally identified with the key and values. The AWS docs explain that while a query is useful to search for items via primary key, a scan walks the full table, but filters can be applied. The two main operations you can run to retrieve items from a DynamoDB table are query and scan. We’ll get to use the AWS Java SDK. (Under reasonable assumptions, average time for element lookup in a hash table is O(1. So if you can query within a Partition Key, that would be ideal. Use up and down keys to navigate. to create query expressions and key. Query is more efficient than scan. Query DynamoDB Items with Node. DynamoDB is a NoSQL key-value store. 您可以使用AWS SDK for Java低级 API 创建具有一个或多个全局二级索引的 Amazon DynamoDB 表、描述表中的索引,以及使用索引执行查询。. A composite primary key composed of two attributes. Getting multiple items using the AWS SDK for Java. We can query for that, and DynamoDB, in turn, gives us 3 items that match this query. We will query the Users table on this one. His NoSQL RDBMS is distinct from the circa-2009 general concept of NoSQL databases. 7 Lambda function - remove item from list 1 I have a "users" table, each one has a user name (the key value) and a list of items (each one represented by ID, a number). Add Multiple Columns Query. Access key ID : Yes : Access key ID of the Flogo ® Connector for Amazon DynamoDB account (from the Security Credentials field of IAM Management Console). For example − A system keeping a track of users, their login status, and their time logged in. Records can be looked up using the hash key very efficiently. How you are going to query to the system should be basically driving the structure of your schema. A Key-value database, also known as a key-value store database, is a type of NoSQL database that uses the simple key and value method to store data. As we saw previously, the overloaded sort key would also return the customer data as last item. With DynamoDB, you can create database tables that can store and retrieve any amount of data, and serve any level of request traffic. The results always return in sort key order, and data type based order with the modifiable default as the ascending order. For the full stack application development, the front end is a necessary part. amazon-dynamodb. Add Sort Key-The sort key is additional key to enrich queries associated with the Primary Key. API Version 2012-08-10 44 Amazon DynamoDB Developer Guide Try a Query - Java. dynamodb (224 example java query nodejs key table python multiple lambda. Contact Us Terms of Use Privacy Policy © 2020 Aerospike, Inc. For more information, see Programming with DynamoDB and the AWS SDKs. CQL Select Query example in Java. aws dynamodb batch-get-item - Query multiple items from DynamoDB Table. Then pass the object to the query method. And, as always, the full source code for the example app can be found over on Github. AWS DynamoDB secondary indexes can be used to reduce cost and improve data access efficiency. On it's best features, it takes care of cluster scaling, hardware. Use Builders class to create a query builder for given DynamoDB entity (see QueryBuilder for full reference) 4: Specify a hash key with hash method and method’s hashKey argument: 5: Specify some range key criteria with the method’s rangeKey argument (see RangeConditionCollector for full reference) 6. We are building out a team and looking for multiple levels but you should have at least 8 years of programming experience. You can query any table or secondary index that has a composite primary key (a partition key and a sort key). If the data type of the sort key is Number, the results are returned in numeric order; otherwise, the results are returned in order of UTF-8 bytes. This is generated dynamically in our serverless. This book will explain how to create, design, and manage databases in DynamoDB using the AWS SDKs and APIs, as well as the AWS management console, a browser-based graphical user interface to interact with the service. java Explore Channels Plugins & Tools Pro Login About Us Report Ask Add Snippet. • The first attribute is the partition key, and the second attribute is the sort key. You are taking one hash key at a time and uploading all its items before going to the next hash key items. No complex query supported. Flexibility. Document History for DynamoDB. Interfacing Amazon DynamoDB with Python using Boto3 With Query you can query on the Hash/Range key, but not on non key attributes. 0 application, the javax. AWS DynamoDB has two key concepts related to table design or creating new table. Every single item in the database is stored as an attribute name (or 'key'), together with its value. fuzzy_max_expansions (Optional, integer) Maximum number of terms to which the query expands for fuzzy matching. Why Secondary Indexes. Because all paginated Query results are loaded into memory and processed, it may consume substantial amounts of memory for large datasets. I am trying to stop duplicate entry and using the following code let params = { TableName: 'followPr. This means that the only way to efficiently query across data containing multiple primary keys is to either explicitly create a Global Secondary Index or perform a full-table Scan. entry by the movie name (which is the hash key for this table), we can use a Query. Watch the next video: Reading data from DynamoDB. Make a new table where the partition key is the e-mail address which you can search and reference your other table from it Make a global secondary index on your existing table with the e-mail address Scan table if it's small enough (this is going to hurt your read quota though). This is generated dynamically in our serverless. Code a Java query by first creating a querySpec object describing parameters. (Explained in a previous post). When I want to query comments made by user, I cycle through that list and grab all the single items. Let's see it if works. Query results are sorted ascending by sort key. They are from open source Python projects. Used to query data with another key besides the primary key. To specify a given attribute as hash key, use keyType: "hash" along with its definition as shown in the above example. The Query operation finds items based on primary key values. dynamodb (235 aws example java query nodejs python table multiple key lambda. Amazon DynamoDB vs Google BigQuery: What are the differences? What is Amazon DynamoDB? Fully managed NoSQL database service. The restriction with DynamoDB is that it doesn't optimise querying across partitions (as it is physically distributed). In this chapter we are retrieving the same piece of data we inserted there by running a CQL select query from our Java application. The goal of Amazon DynamoDB is to eliminate this complexity and operational overhead for our customers by offering a seamlessly scalable database service. However, both have their own working style and their own pros and cons. DynamoDB is a fully managed NoSQL database that supports both document and key-value store models. png for user X’s session”) * app server generates a guid to be used as the S3 key for the photo to be uploaded to S3 (so the. Query DynamoDB Items With Java. Read Consistency for Query and Scan. The key-value database treats the data as a single opaque collection of key and value pairs. Now, our DynamoDB client is configured to use DynamoDB local if we're running locally, or use the default options if running in Lambda. A better solution that comes to my mind is to maintain the total number of item counts for such tables in a separate table, where each item will have Table name as it’s hash key and total number of items in that table as it’s non-key attribute. Each DynamoDB table can only have up to one tag with the same key. Update item in DynamoDB using Java. Using Java in BatchGet operations requires creating a DynamoDB class instance, TableKeysAndAttributes class instance describing a primary key values list for the items, and passing the TableKeysAndAttributes object to the BatchGetItem method. When a user writes a comment, store the primary key within the user table (so, within some attribute "createdcomments", store [{associated post id, timestamp}] ). The batch-write-item call will result on a map with the unprocessed requests, as well as the consumed capacity units (we won’t get the latter on a local DynamoDB). DynamoDB Streams + Rockset. DynamoDB query examples. JPQL is similar to SQL, but operates on objects, attributes and relationships instead of tables and columns. DynamoDB is reported to run exclusively on SSD storage devices. We typically have to query on the Projects for a User, and on the Documents for a Project. the primary key is the attribute email. All supported language implementations are interoperable. 处理本地二级索引:Java. Issue a query using a hash key is as simple as it gets. Athena processes structured, semi-structured and unstructured data sets including CSV, JSON, ORC, Avro, and Parquet. DynamoDB Queries. This lesson will only cover the basics of using these API calls. We won't go into the details of querying DynamoDb in general. AWS DynamoDB - combining multiple query filters on a single non-key attribute in java. A query can have no more than one NOT_EQUAL filter, and a query that has one cannot have any other inequality filters. You can create one or more secondary indexes on a table. The hash key should be chosen in such a way. You see, really there is no standard defining the correct way to encode key/value pairs into a query string. DynamoDB offers four low-level actions for data reading − GetItem − It accepts a primary key and returns attributes of the associated item. All supported language implementations are interoperable. dynamodb (235 aws example java query nodejs python table multiple key lambda. SQL tutorial provides basic and advanced concepts of SQL. Sets the maximum number of items to retrieve in each service request to DynamoDB and returns a pointer to this object for method-chaining. As we saw previously, the overloaded sort key would also return the customer data as last item. DynamoDBMapper. I am trying to stop duplicate entry and using the following code let params = { TableName: 'followPr. AWS DynamoDB secondary indexes can be used to reduce cost and improve data access efficiency. 8 keys to DynamoDB success throttling and cut your bill in a write-heavy environment where keys may be written multiple times. On this tutorial we will issue some basic queries against our DynamoDB tables. The key-value database treats the data as a single opaque collection of key and value pairs. As a workaround you can create local secondary index for each field that you want to be a range key. I know the general way of mapping an entity with a table with @Entity and @Table annotations, but I can't understand how to do it with Views. This will require to write a custom query logic and handle inevitable throttling in query operations. An API Gateway is setup to trigger the Lambda function. API Gateway is a fully managed service that enables developers to create, publish, maintain, monitor, and secure APIs at any scale. DynamoDB Python 2. Getting multiple items using the AWS SDK for Java. Second, a query parameter, the time, which is the primary sort key for the DynamoDB table. To reverse the sort order, set the ScanIndexForward parameter to false. Contribute to aws/aws-sdk-java development by creating an account on GitHub. It is unclear many of the details of the DynamoDB implementation as Amazon often refers to these internal factoids as proprietary i. For example, suppose your query returns 10 items whose combined size is 40. Query String Standards (or the Lack Thereof) All this looked rather unsatisfactory to me, but, in a way, I was actually wrong. To specify a given attribute as hash key, use keyType: "hash" along with its definition as shown in the above example. You specify the primary key when you create a table, and it uniquely identifies each item. Update item in DynamoDB using Java. delegated_keys. i think this is not possible in single query, because sql does not provide multiple delete statement, but only method is to set the cascade option in relationship, then you will be able to delete more than 2 table as you want. Then, we'll explore two basic API calls: PutItem and GetItem. You can read about it the AWS documentation pages if you want to know more. Getting multiple items using the AWS SDK for Java. We are building out a team and looking for multiple levels but you should have at least 8 years of programming experience. In a long, earlier article on Java keytool, keystore, and certificates, I demonstrated how to list the contents of a Java keystore file, but to simplify things a little for this tutorial, I'm just going to show how to query a Java keystore file using the keytool list command. It works if I make a single GetItem query. fuzzy_max_expansions (Optional, integer) Maximum number of terms to which the query expands for fuzzy matching. Query DynamoDB Items with Node. DynamoDB stores data in tables which is a collection of items and the items are key-value pairs referred by DynamoDB as attributes. DynamoDB doesn’t require that you use indexes, but they give your applications more flexibility when querying your data. You can use this parameter query to search across multiple fields. The growth of the previous example slows. MongoDB Manual: How to delete documents in MongoDB. It is based on boto and provides following features:. First, Query commands are much slower than a straight GetItem command, where you are given both the precise hash key and range key to match. Our visitors often compare Amazon DynamoDB and Neo4j with MongoDB, Microsoft Azure Cosmos DB and Elasticsearch. 22 September, 2014. js, Java, JavaScript, Python,. In the first post , I…. First, Query commands are much slower than a straight GetItem command, where you are given both the precise hash key and range key to match. com as part of the Amazon Web Services portfolio. But as in any key/value store, it can be tricky to store data in a way that allows you to retrieve it efficiently. Each DynamoDB table can only have up to one tag with the same key. Displayed here are Job Ads that match your query. The JDBC API can also interact with multiple data sources in a distributed, heterogeneous environment. Side-by-side comparison of DynamoDB vs. View Saketh Paranjape’s profile on LinkedIn, the world's largest professional community. Second, a query parameter, the time, which is the primary sort key for the DynamoDB table. To reverse the sort order, set the ScanIndexForward parameter to false. This means that the only way to efficiently query across data containing multiple primary keys is to either explicitly create a Global Secondary Index or perform a full-table Scan. We chose Amazon DynamoDB because it provides the input data representation and query patterns necessary for a FHIR data repository. For an overview on tagging DynamoDB resources, see Tagging for DynamoDB in the Amazon DynamoDB Developer Guide. the attribute that i am setting the condition for is of type number. With today's release, we are extending this model with support for query filtering on non-key attributes. PostgreSQL System Properties Comparison Amazon DynamoDB vs. Get the combined text of all the matched elements. Use Query rather than Scan to retrieve all items for user_id - this works regardless of the combined hash/range primary key in use, because HashKeyValue and RangeKeyCondition are separate parameters in this API and the former only targets the Attribute value of the hash component of the composite primary key. The offering primarily targets key-value and document storage. However, using Amazon's DynamoDB has it's own benefits, not least from speed, scalability, affordability and freeing your time up from…. It makes sense to use the random numbers as part of your Hash Key so your records can be evenly distributed across the DynamoDB partitions, however, you have to do it in a way that your application can still calculate those numbers when you need to retrieve the records. Code a Java query by first creating a querySpec object describing parameters. i think this is not possible in single query, because sql does not provide multiple delete statement, but only method is to set the cascade option in relationship, then you will be able to delete more than 2 table as you want. dynamodb (235 aws example java query nodejs python table multiple key lambda. You can query any table or secondary index that has a composite primary key (a partition key and a sort key). In what situation do you use Simple Hash Keys on DynamoDB? database,amazon-web-services,amazon-dynamodb,key-value-store. The primary key is the only required attribute for items in a table. OK, that's it!. aws dynamodb batch-get-item - Query multiple items from DynamoDB Table. The basic way to achieve this in boto3 is via the query and scan APIs:. Batch Retrievals with Java. The user will need the following permissions. …There's a scan query that searches the entire table,…and you can filter the results. Connect2id server 7. The primary key is the only required attribute for items in a table. CQL Select Query example in Java. In this Video we will learn to create DynamoDB tables using JSON code and will load the data into DynamoDB tables using Command Line Interface CLI of AWS. CM Training is a leading integrated training provider and training management service. AutoQuery DynamoDB Global Index Queries. 13th Feb 2012 +0. DynamoDB uses primary keys to uniquely identify each item in a table and secondary indexes to provide more querying flexibility. 3) – Rows: 112. You can specify the hash key and optional range key in order to get the desired items. It has simple storage and query methods, allowing you to store and access data items with a flexible number of attributes using simple “Put” or “Get” web services APIs. DynamoDB tables are created with the Layer2. Document History for DynamoDB. This means it doesn’t store data in a structured, relational mapping; instead, it stores JSON objects in a simple key-value format. DynamoDB: DynamoDB uses tables, items and attributes as the core components that you work with. DynamoDB query examples. The following table describes the important changes in each release of the DynamoDB Developer Guide from July 3, 2018, onward. NoSQL perform well for database size and server performance. DynamoDB Streams + Rockset. They require specification of partition keys and equality conditions, with the option to specify sort keys and conditions. dynamodb query multiple keys python (3) Ahh ok, figured it out. Using Java in BatchGet operations requires creating a DynamoDB class instance, TableKeysAndAttributes class instance describing a primary key values list for the items, and passing the TableKeysAndAttributes object to the BatchGetItem method. A table is a collection of items, and each item is a collection of attributes. (Explained in a previous post). Interfacing Amazon DynamoDB with Python using Boto3 With Query you can query on the Hash/Range key, but not on non key attributes. Query is more efficient than scan. Q: What kind of query functionality does DynamoDB support? DynamoDB supports GET/PUT operations by using a user-defined primary key. While creating the secondary index in DynamoDB, one needs to first specify its key attributes after which it can be used to run a query or scan a table by following standard procedure. Query to MySQL. The restriction with DynamoDB is that it doesn't optimise querying across partitions (as it is physically distributed). Here we also discuss the MongoDB vs DynamoDB key differences with infographics, and comparison table. Watch the next video: Reading data from DynamoDB. Comprehend the DynamoDB data model and how to build the efficient schema of DynamoDB tables; Decipher the architecture of DynamoDB and its core features. Explore key analytics concepts, common methods of approaching analytics challenges, and how to work with services such as Athena, RDS, and QuickSight. This Ec2 instance has been granted an IAM role, with which I can directly access the Dynamodb by using aws CLI: aws dynamodb list-table. (Under reasonable assumptions, average time for element lookup in a hash table is O(1. What Is Amazon DynamoDB? • • • 1. If you want to read the data using non-key attributes, you can use a secondary index to do. With DynamoDB, you can create database tables that can store and retrieve any amount of data, and serve any level of request traffic. The Query operation finds items based on primary key values. DynamoDB "OR" conditional Range query. dynamo_objects. The partition key would be the CustomerId, and the sort key would be the OrderId. query, multiple requests are made to DynamoDB if needed to retrieve the entire result set. • Hash of partition key determines the partition where the item is stored. dynamodb queries. We can implement a consistent and scalable HTTP-based programming interface (also referred to as RESTful services) to access backend services like Lambda functions, further AWS services (e. DynamoDBQueryExpression. First, Query commands are much slower than a straight GetItem command, where you are given both the precise hash key and range key to match. Indexes are maintained automatically for additions, updates or deletes. It looks like your exact syntax may be a bit off, but I'm not 100% sure there. This is explained in greater detail in DynamoDB's Data Model documentation. The examples are extracted from open source Java projects. Power BI detects the column behavior from the Amazon DynamoDB metadata retrieved by the CData connector. Make sure to take in to account the capacity read units for each query. Today, we are extending expressions support to key conditions in the Query operation for even simpler queries. It requires specifying the partition key value, with the sort key as optional. If you're not familiar with Laravel, Laravel Eloquent and DynamoDB, then I suggest that you get familiar with those first. If the data type of the sort key is Number, the results are returned in numeric order; otherwise, the results are returned in order of UTF-8 bytes. Basically, you store objects (representable in JSON), matched to a key. 前記事の AWS DynamoDBの項目の取得(Java) に続いて、今度はクエリのAPIを詳しく使ってみます。 いろいろなパターンを実装しました。 queryメソッドはハッシュキーのみの検索、queryReplyはハッシュキーとレンジキーの複合検索、queryReplyByUserはローカル. First, a path parameter, the date, which is the primary partition key for the DynamoDB table. DynamoDB can be taken as a glorified hash map. This is a general purpose distributed locking library built on top of DynamoDB. This question already has an answer here. The other attributes besides the key that you want copied in the index have to be specified (known as projection). Query by userID if userID has been made a secondary index. When using a table with a composite primary key, you may have multiple items with the same partition key but different sort keys. Next a Lambda function which inserts the data into DynamoDB table. For our student table, the student id - stdid will be the hash key. So lets say you’re doing you’re best to data model all around one partition. Using Java in BatchGet operations requires creating a DynamoDB class instance, TableKeysAndAttributes class instance describing a primary key values list for the items, and passing the TableKeysAndAttributes object to the BatchGetItem method. Project Node. Query is more efficient than scan. This took a long time to get to work, but in the end it was super simple. Sorting in DynamoDB is only supported under certain criteria, such as sorting by a range key or index range key, where all the items are for the same hash key. DynamoDB: DynamoDB uses tables, items and attributes as the core components that you work with. Composite keys are combination of multiple keys. The real focus here is to introduce DynamoDB and show how to deal with the restrictions it imposes. Please select another system to include it in the comparison. Query and Scan are powerful operations that help us to retrieve data. The max-keys query string parameter is an integer that specifies the maximum number of objects you want returned in a list of objects. It allows you to select multiple Items that have the same partition ("HASH") key but different sort ("RANGE") keys. It allows you to use the Query API to retrieve all the items for a single composite partition-sort key across a range of sort keys. The best candidate for a query like this would be the Users table by searching using the email hash key. The Hash Key is the status of a project (ie: new, assigned, processing, or complete). js Lambda & DynamoDB Purpose The purpose of this project is to show a way to get your AWS Lambda (Node. This has a been a guide to the top differences between MongoDB vs DynamoDB. Event Date: November 12, 2019. Couchbase Server Vs DynamoDB - A Quick Comparison Denis Rosa, Developer Advocate, Couchbase on December 19, 2017 Choosing a NoSQL database is way more complicated than selecting an RDBMS, the world of NoSQL database comes in multiple flavors, each one has a specific design focused on solving a different set of problems. These are, in order: a file called AwsCredentials. DynamoDB is a managed NoSQL database service provided by Amazon Web Services. DynamoDB schema has to be approached via a query mindset. DynamoDB supports multiple native data types (numbers, strings, binaries, and multi-valued. Dynamodb Secondary Index. You can create the secondary indexes by specifying the key attributes and create a query for the same. DynamoDB count total rows that match key and filter expression also fixes the reserved word issues: DynamoDBCount. Update item in DynamoDB using Java. In this quick article, we have learned how to create Lambda application with DynamoDB and Java 8. us-east-1 » Attributes Reference In addition to all arguments above, the following attributes are exported: id - The name of the DynamoDB Global Table arn - The ARN of the DynamoDB Global Table » Import DynamoDB Global Tables can be imported using the global table name, e. Watch the next video: Reading data from DynamoDB. DBMS > Amazon DynamoDB vs. ALT, CTRL, SHIFT, ESC). The overhead in each of the API request to DynamoDB can really. Then, we'll explore two basic API calls: PutItem and GetItem. The most efficient method is to fetch […]. Amazon DynamoDB provides a native API for HTTP and SDKs for Java, PHP and. python - boto dynamodb batch_write and delete_item -- 'The provided key element does not match the schema' amazon web services - Query dynamoDB with non hash key field (with boto / python) amazon web services - Increment counter in AWS DynamoDb using boto. Here is an example with the Java SDK:. You specify the primary key when you create a table, and it uniquely identifies each item. Aqua Data Studio, SQuirreL SQL, DatabaseSpy, RazorSQL) would allow you to write a query across multiple databases? Just register the UnityJDBC driver with your query tool, and you can write queries that span databases in 5 minutes. …And then we're going to perform…the two types of query operations. The variable mongoConnection is declared multiple times, that means that if the connection string changes then we need to change multiple places causing possibilities of missing one instance and causing errors. Athena processes structured, semi-structured and unstructured data sets including CSV, JSON, ORC, Avro, and Parquet. It has simple storage and query methods, allowing you to store and access data items with a flexible number of attributes using simple “Put” or “Get” web services APIs. No need to define the LSI on this case. secretKey in the Java system properties; the environment variable AWS_SECRET_KEY. Query to MySQL. First, a path parameter, the date, which is the primary partition key for the DynamoDB table. DelegatedKey. The user will need the following permissions. This has a been a guide to the top differences between MongoDB vs DynamoDB. Here we also discuss the MongoDB vs DynamoDB key differences with infographics, and comparison table. Step 1: Create a DynamoDB table: Create a DynamoDB table named Employee with the attributes of primary key as emp_id. The simplest form of query is using the hash key only. amazon-dynamodb. The Apache Lucene TM project develops open-source search software, including:. I am trying to stop duplicate entry and using the following code let params = { TableName: 'followPr. Query to MySQL. This post will explain how to setup both local and remote AWS DynamoDB instances. Use the KeyConditionExpression parameter to provide a specific value for the partition key. Then, we'll explore two basic API calls: PutItem and GetItem. The growth of the previous example slows. Step one in creating a CRUD application for a database is create a table. us-east-1 » Attributes Reference In addition to all arguments above, the following attributes are exported: id - The name of the DynamoDB Global Table arn - The ARN of the DynamoDB Global Table » Import DynamoDB Global Tables can be imported using the global table name, e. Search an Amazon DynamoDB table data where the query operations search only primary key attribute values. •All items with the same partition key are stored together, in sorted order by sort key value. The KeyConditionExpression expression would look like. • The first attribute is the partition key, and the second attribute is the sort key. It allows you to select multiple Items that have the same partition ("HASH") key but different sort ("RANGE") keys. DynamoDB stores data in tables which is a collection of items and the items are key-value pairs referred by DynamoDB as attributes. com courses again, please join LinkedIn Learning. See the complete profile on LinkedIn and discover Saketh’s. The Java code for this (using the AWS SDK and a DynamoDBMapper) is:. …And then we're going to perform…the two types of query operations. On it's best features, it takes care of cluster scaling, hardware. query, multiple requests are made to DynamoDB if needed to retrieve the entire result set. It permits changes to its default eventually consistent read setting. i think this is not possible in single query, because sql does not provide multiple delete statement, but only method is to set the cascade option in relationship, then you will be able to delete more than 2 table as you want. The examples were created and tested on Ubuntu Linux. I've inserted a couple more records into the demo DynamoDb table in preparation for the queries: There's an important distinction between a "query" and a "scan" in DynamoDb. Because Geo Library calls multiple DynamoDB Query requests and processes the results in memory, it is not suitable for mobile device use. The Query operation finds items based on primary key values. For our student table, the student id - stdid will be the hash key. Conditions on multiple range keys (" are found in. We'll concentrate on the specific query to get one data record from our test IP range table. For the operation hash-map, the key is an operation type (either :put or :delete), and the values a vector of items to be put, or a vector of keys to be deleted.