Functions dealing with attribute dimensions, Children(East) /* Valid in Calc and MDX */ East. Amazon S3 Select always treats a JSON document as an array of root-level values. For example, suppose you want to find the percent change between this year's sales data and last year's sales data. Apache Calcite for Enabling SQL Access to NoSQL Data Systems Geode Adapter expressions into OQL queries JOIN For collocated Regions only AGGREGATE YES for. Expression subqueries return a single value. Waiting for 8. Operator and function support for data types. To obtain objects, a query usually uses path expressions to navigate through the relationships. Queries XML files located on remote databases using local files containing XPath queries and outputs the results to an XML file stored locally. Does it make sense to support window expressions inside aggregate. Unfortunately, we do not have time now to unload and reload the data into re-designed tables. Built-in functions. The View Update Problem in the OutSystems Aggregate Language Lu´ıs Carvalho 1, Hugo Lourenc¸o3, and Jo˜ao Costa Seco,2 1 Faculdade de Ciˆencias e Tecnologia, Universidade NOVA de Lisboa, 2 NOVA LINCS, 3 OutSystems, Inc. PDF | In this paper, we study the evaluation of twig pattern queries based on the ordered tree matching. Based on layer data and prebuilt or user defined functions, Expressions offer a powerful way to manipulate attribute value, geometry and variables in order to dynamically change the geometry style, the content or position of the label, the value for diagram, the height of a composer item, select some features, create virtual field. Click the OK button to close the Query Builder. Thanks, Mohit. 0 provides builtin support for Hive features including the ability to write queries using HiveQL, access to Hive UDFs, and the ability to read data from Hive tables. You must use appropriate expression notation whenever expr appears in conditions, SQL functions, or SQL statements in other parts of this reference. it has to be rolled up. I've noticed quite a people searching my blog for this topic so I thought I'd throw some examples together. Soil moisture modeling review. The query is converted to a union so that both indexes can be used, in case there are separate indexes for a and b. The Oracle BI Server simplifies the SQL statements needed to craft aggregate queries. I used LOD for budget and so showing right numbers for budgets (because quotas are not bottom up and adding them will not match higher level quota and also at the root). The Spatial module supports the object model of Simple Feature Access in queries and object binding. A window in which you can create a filter from scratch. 10-beta, Sphinx supports two different indexing backends: "disk" index backend, and "realtime" (RT) index backend. aggregate_expression This is the column or expression that the aggregate_function will be used against. The ideal condition would be, I admit, that men should be right by instinct. An aggregate expression represents the application of an aggregate function across the rows selected by a query. Both of these keys have dictionary values containing a single key: host. LogicalPlan Contract — Logical Operator with Children and Expressions / Logical Query Plan references only with the Dataset a aggregate function over a. Because some browsers/HTTP frameworks do not support HTTP GET-with-entity, this command also supports the PUT method even though no modifications are made. Filter, compute, join, and pattern expression windows support the use of global functions. Then during the rewrite, when I get to the select expression with that alias I simply tack on all the aggregate expressions by inventing columns for them. A projection interface using @Value is an open projection. Cursors allow you to consume only part of the response, allowing you to fetch additional results as needed. Generate and Compile a Binder instance that on 'bind()' call runs Geodes' query method 1. OData (Open Data Protocol) is an ISO/IEC approved, OASIS standard that defines a set of best practices for building and consuming RESTful APIs. In Mongo, aggregations work as a pipeline, or a list of operators/filters applied to the data. A hierarchical query is a type of SQL query that handles hierarchical model data. This is something we need for 'Material Aggregation'. Aggregate Query via Entity. This is analogous to the LINQ to XML execution described above. Aggregate query parameters can be provided in an input entity instead of URI parameters. Keep in mind that this is only a minimum requirement. But there is an issue with query. In other words: when a new data package has been loaded into an InfoCube it has to be rolled up into the MOLAP aggregates if the InfoCube has been set up for MOLAP. Mix of text and element children in many places, but east should have only a text node. $match takes a document that specifies the query conditions. He also updates data element names to meet new ISO-11179 rules with the same experience-based teaching style that made the previous editions the classics they are today. Criteria Queries can only be used to fetch the records only as they do not support updates or deletes to the database. No other expression forms described in this chapter are valid. Practical performance, security, and architectural solutions. xc3w1 function do not support the simple arithmetic expressions nor the constants queries with ansi joins. I have seen domain entities filled with relationships and properties only there because some part of the GUI requires it. Does it make sense to support window expressions inside aggregate. Sophocles, Oedipus Rex This chapter describes how to combine the values, operators, and functions described in earlier chapters evaluate to a value. Complex EQL queries can be build that feature a more elaborate select list utilizing expressions, may join multiple streams or may contain a where clause that with search conditions. COUNT — An aggregate function that returns the number of rows in a table or a specified column. The expressions that are not encapsulated within an aggregate function and must be included in the GROUP BY clause. Group and aggregate the rows from the table first, define a table expression based on the grouped query, and then join the table expression with the table that has the column in question. When using variables or assertions that extract data from JSON bodies, you'll need to specify a JSON object expression to locate the data to extract. An aggregate function reduces multiple inputs to a single output value, such as the sum or average of the inputs. Only C# has a type for working with complex numbers. If the data source does not support such a query, then the data engine can substitute a designated literal value for a null value when constructing the XML. This is the same limitation SQL Server has, and PostgreSQL had at the time when SQLite 3. Mix of text and element children in many places, but east should have only a text node. You can use variables in metric queries and in panel titles. This reference guide is a work in progress. Book Description Essential Skills--Made Easy! C#: A Beginner's Guide offers a step-by-step approach to learning object-oriented programming with C# and the. Thank you, that was perfect. I noticed your aggregate doesnt include a numeric_expression. The most general definition of the function is given first. But SPARQL property paths only return the start and end nodes of a path. Aggregate Expressions. This is something we need for 'Material Aggregation'. When I remove the Net Income column, the query shows up in Excel's list. A shebang (#!) is always required for executable facts on Unix. You can create your own aggregate expressions with the CREATE AGGREGATE statement and then invoke these aggregates wherever you can invoke the built-in aggregates. Numerous proposals. Place the aggregate expression in a subquery. The Couchbase Data Platform is the only platform that extends SQL to support JSON data natively via N1QL queries. If you're experiencing inappropriate choices of a stream aggregate algorithm with columnstore (meaning there's also a sort involved since columnstore isn't ordered), that's usually the result of a cardinality under estimation. For example, the following query reports the salary for each employee, along with the average salary of the employees within the department. All selecting queries support DataRows option, e. Cursors allow you to consume only part of the response, allowing you to fetch additional results as needed. My previous article explained how to calculate frequencies using T-SQL queries. Therefore if multiple events are inserted to the event table having the same index value only last inserted event will remain in the table. Expressions aggregate the search results into a single value to return. The only downside is that you lose the neatness of using RAW. NASA Technical Reports Server (NTRS) Hildreth, W. The Apache Lucene Project Management Committee decided in a vote, that the Apache Lucene sub-project "Open Relevance" will be discontinued. Strongly-typed and schema-driven. No other expression forms described in this chapter are valid. All windows support global functions for output splitters on the specified window. Aggregates should not require a change just because we need to display more data in the GUI. The query syntax is identical to the read operation query syntax; i. A hierarchical query is a type of SQL query that handles hierarchical model data. [IMPALA-1670] - Support multiple partition specs in ALTER TABLE ADD PARTITION [IMPALA-1972] - Queries that take a long time to plan can cause webserver to block other queries [IMPALA-2328] - Parquet scan should use min/max statistics to skip blocks based on predicate. As a result, the "orderby" and "select" clauses must refer back to this root entity. Hi, This is similar to request posted in Rollup Hierarchy SQL I want to 'Aggregate' only Leaf nodes of the BOM Tree. Changes the definition of a conversion. The root aggregate contains the root volume, which contains special directories and configuration files that help you administer the storage system. com released new Apex functionality for aggregate functions in SOQL. I noticed your aggregate doesnt include a numeric_expression. Michael (DevExpress Support) 05. I did not know that relationship names are based on the lookup field and not the master object. For example, a domain service might support a calculation. (Recursive) Common Table Expressions in MySQL; A nice “hidden” feature is the support of new and calculating an aggregate function only on those values. Of course, the two queries above are not entirely equivalent. This page is a introductory tutorial of the Structured Query Language (also known as SQL) and is a pioneering effort on the World Wide Web, as this is the first comprehensive SQL tutorial available on the Internet. This is adequate for many situations since rapid multiple sequential queries allow users to satisfy their information needs. This is a legacy behavior that evolved because historically BigQuery did not support CROSS JOIN and BigQuery users regularly needed to write UNION ALL queries. These predefined functions were accessed in the predicate syntax using custom keywords (for example, MAX(1, 5, 10)). Kochava Query coerces the result type of an expression to another type if needed to match function signatures. The AVG aggregate is even more complex: you need to compute both the SUM and the COUNT (using local-global aggregation for each), and then divide them to present the average. Expression Documentation. NET doesnt support annonymous methods and lambda expressions with statement body now. Many past proposals have taken a basically relational query language (typically SQL), and modified it by the addition of a few constructs: typically a "contains" operator and some features for matching strings within text chunks against regexes, or against word-roots. The code above works just fine, but has some issues. [CALCITE-1529] Support CREATE TABLE in tests (and only in tests) [CALCITE-1527] Support DML in the JDBC adapter (Christian Tzolov) [CALCITE-1523] In RelBuilder, add field method to reference input to join by alias (Jess Balint) [CALCITE-1524] Add a project to the planner root so that rules know which output fields are used. the more specific, and stops as soon as a valid answer is found for the function. Expression subqueries return a single value. I appreciate the help!. only root queries support aggregate expressions. Enabling these applications require real-time monitoring and analysis tools that support: High-throughput concurrent writes of millions of data points potentially from multiple data streams; Online queries over raw data, aggregate statistics and. However, for compatibility reasons, Amazon S3 Select allows you to omit the wildcard if you don't include a path. You can extend the base class and define whatever pre- and post-processing methods you need. However, how are queries to entities within the aggregate modeled? Suppose the case of an Orders aggregate. I noticed your aggregate doesnt include a numeric_expression. A function, such as Sum, Count, Avg, or Var, that you use to calculate totals. For any XPath implementation there needs to be a way to map from the prefixes used in the XPath expression to the actually URIs that they represent. A regular expression is a "prefix expression" if it starts with a caret (^) or a left anchor (\A), followed by a string of simple symbols. You can use a column expression for these purposes: To create a function-based index. However, when we are writing real-life applications, we have to be able to create dynamic database. An adapter has also been added for Apache Kafka. Changes the definition of a conversion. Lucene Index vs Property Index. The Root field is a number type and the ID field is a string type. These predefined functions were accessed in the predicate syntax using custom keywords (for example, MAX(1, 5, 10)). There are also a few snippets that rely on them. The root Entity can hand references to the internal Entities to other objects, but they can only use them transiently (within a single method or block). named sets. It not only enables us to write queries without doing raw SQL, but also gives us some Object Oriented control over the queries, which is one of the main features of Hibernate. The LINQ Expressions API includes factory methods that allow you to build up the predicate by hand. However it differs from property index in following aspects. a URL without * the host part, that starts with a slash. The only time the query works without a hint is if I only try to get the loan hierarchy by explicitly specifying the root loan(s). The expressions that are not encapsulated within an aggregate function and must be included in the GROUP BY clause. Amazon S3 Select always treats a JSON document as an array of root-level values. ) in the calculation. As it is clearly said in the exception, the root cause is no Encoder found for java. Access SQL does not support the syntax you are trying to use. A projection interface using @Value is an open projection. As such, Druid SQL only has partial support for NULLs. Useful free and paid Microsoft SQL Server utilities and tools - a complete list of 275 SQL Server Utilities updated on Jan 24, 2019. e) Code size is a lot smaller and development a lot faster. The query plans are represented as a tree of stages, in which each stage passes its results to its parent node. [IMPALA-1670] - Support multiple partition specs in ALTER TABLE ADD PARTITION [IMPALA-1972] - Queries that take a long time to plan can cause webserver to block other queries [IMPALA-2328] - Parquet scan should use min/max statistics to skip blocks based on predicate. The aggregate functions can only take field reference expressions which resolve to non. The Account is the aggregate root of this relation. Only group properties which are the expressions that are used for grouping (e. 1 APAR Fix list contains list of APARs shipped for each fix pack in DB2 Version 10. it has to be rolled up. What is a Common Table Expression (CTE) A CTE can be thought of as a temporary result set and are similar to a derived table in that it is not stored as an object and lasts only for the duration of the query. * * These will relatively rarely need to be set manually, unless you are * splitting style sheets or images outside the main document root. Thank you, that was perfect. finally, click on the "<--> label on the right-hand side of the expression and enter a value of "3" in the Edit tab. It has a child node below it. archive: A compressed MarkLogic Server database archive created using the mlcp export command. A name space prefix resolver is always required. Criteria Queries can only be used to fetch the records only as they do not support updates or deletes to the database. 2, which provides fluent query builder, SQL query, update-in-place, ES2017 syntax support, and true intellisense experience. Support for aggregate functions in SOQL Developer Tools We often need to bring back way more data than we need to and do extra processing on the client because we can't use aggregate functions in SOQL queries. One of the table functions is pipelined, the other is not. Technical Tutorials Advanced MDX queries. Expression items can use SQL statements and Ignition's Expression language to automatically determine the value of an Expression Item. If not is there some other way to check, how a query performs within the aggregation fra. Based on how well it does, the Planner either keeps or evicts the cache entry, and replaces it with a new plan. Queries and Subqueries. Hardware design for performance queries. 5 and later, function expressions also support arbitrary method invocations. Bad! If a Campaign had more than 20 statuses, the code would fail. However, the root class can be configured so queries on it return only instances of itself, without instances of its subclasses. com released new Apex functionality for aggregate functions in SOQL. The store root node is '/'. sql script shown below. We support the following list of variables to be used in a manual query. In our case we want to enforce that new entries can only added to the Account by using a designated method. Currently we only allow dynamic partition columns to be the last column(s) in the partition clause because the partition column order indicates its hierarchical order (meaning dt is the root partition, and country is the child partition). The FROM clause of the recursive member can only refer to the CTE expression once. Starting from version 1. The query it may complain that the query is read-only. Interpolation. Read-only transactions are useful for running multiple queries while other users update the same tables. Expression subqueries return a single value. A tree intended to allow many kinds of path expressions. A hierarchical query is a type of SQL query that handles hierarchical model data. I did not know that relationship names are based on the lookup field and not the master object. 4 – Common Table Expressions (WITH queries) On 4th of September Tom Lane committed another great patch. You often see these functions (for example, Sum, Count, and Avg) referred to as aggregate functions. The purpose of this review is to address the reasons and methods for conducting optical remote sensing within the flux tower footprint. MDX (Multidimensional Expressions) is used by ActivePivot, a mixed-workload database that lets you run real-time queries with hundreds of dimensions on data that gets refreshed frequently. The expressions in the following table use SQL (Structured Query Language) functions that aggregate or summarize data. Apache Calcite for Enabling SQL Access to NoSQL Data Systems Geode Adapter expressions into OQL queries JOIN For collocated Regions only AGGREGATE YES for. To use these features, you do not need to have an existing Hive setup. The criteria API is only for dynamic queries, and cannot be used in meta-data or named queries. only root queries support aggregate expressions. The rationale formations of view expressions. ora / spfile comparados con la base de datos Oracle 12. We believe that support for full regular expressions over graph edges is important, particularly if combining provenance data from multiple sources whose attribute names may not be fully consistent. The following facts apply to the root aggregate: Starting with Data ONTAP 8. Query on TPC-H SF100 dataset fails with "Hash join does not support schema changes" [MapR-DB JSON. An aggregate function reduces multiple inputs to a single output value, such as the sum or average of the inputs. 1 Consider the two similar tree-pattern-based subscriptions * and + shown in Figure 1, where,* matches any document with a root element labeled “CD”. Today we’re releasing a new update to Power BI that brings lots of new capabilities to enable users to create reports. The root Entity can hand references to the internal Entities to other objects, but they can only use them transiently (within a single method or block). An xml datum can contain one of two sorts of values: a document or a fragment. This section outlines the rules that the Oracle BI Server follows for whether a query contains a GROUP BY clause and, if a GROUP BY clause is specified, what results you should expect from the query. Aggregates are the core mechanism of the data manipulation. 1, new systems are shipped with the root volume in a 64-bit root aggregate. You can't use a LIMIT clause in a query that uses an aggregate function, but does not use a GROUP BY clause. aggregate() Stages ¶ Starting in version 3. Here is a simple aggregate query for demonstration. Since you don't want to group you can't use LIMIT like that. Support for range queries has been requested by Yoshinori. Delete queries should only be used for bulk deletes, regular deletes to objects should be performed through calling the EntityManager remove() API. The Cover Pages is a comprehensive Web-accessible reference collection supporting the SGML/XML family of (meta) markup language standards and their application. This page provides concepts about query execution plans and how they are used by Cloud Spanner to perform queries in a distributed environment. autoconnect (bool) – Automatically connect to database if attempting to execute a query on a closed. The default ordering is ASC. Because of the need to support expression trees, (probably for speed compared to the slower Refelections class support), the Expression class is set up mostly using a. Today we’re releasing a new update to Power BI that brings lots of new capabilities to enable users to create reports. For aggregation expression operators to use in the pipeline stages, see Aggregation Pipeline Operators. Non-Aggregate Queries SelectItems may include: SelectExpressionItem: Any expression that Eval. The root blank node refers to the SELECT statement, which is described with two triples for its two clauses, the first one being the projection clause labeled as "SELECT" and the second one being the FROM one. Report item expressions can only refer to fields within the current data set scope or, if inside an aggregate, the specified data set scope. Any results returned where the aggregate function or BY clause includes a wildcard character are only the most recent few minutes of data that has not been summarized. in offline queries for root-cause analysis and system opti-mizations. Hi Sakthivel, You can't use a LIMIT clause in a query that uses an aggregate function, but does not use a GROUP BY clause. Yuli Vasiliev is a software developer, freelance author, and consultant currently specializing in open source development, Java technologies, databases, and SOA. To use these features, you do not need to have an existing Hive setup. An aggregate function reduces multiple inputs to a single output value, such as the sum or average of the inputs. Support for aggregate functions in SOQL Developer Tools We often need to bring back way more data than we need to and do extra processing on the client because we can't use aggregate functions in SOQL queries. However, the root class can be configured so queries on it return only instances of itself, without instances of its subclasses. For example, the following query reports the salary for each employee, along with the average salary of the employees within the department. For aggregation expression operators to use in the pipeline stages, see Aggregation Pipeline Operators. That will add the "HAVING last_name_count >= 3" expression to the query so that, this time, the query only shows actors whose last names appear three or more times in the table:. There are two MIB files for FortiGate units - the Fortinet MIB, and the FortiGate MIB. Therefore if multiple events are inserted to the event table having the same index value only last inserted event will remain in the table. The first section of the page is called Replacements to be made and lets you specify which data to replace and what to replace it with. A hierarchical query is a type of SQL query that handles hierarchical model data. GROUP BY clause. With an aggregate query, the ORDER BY cannot specify a column that is not in the SELECT list. API performance monitoring. Some Functions Are Only Available for Table Calculations. Since you don't want to group you can't use LIMIT like that. This document outlines the operator syntax for this query language. Your code is expected to support both aggregate and non-aggregate queries with the following features. The aggregate root backing the projection is available in the target variable. But for those objects that cannot be obtained by navigation, you can use a range variable declaration to designate a starting point, or query root. Does it make sense to support window expressions inside aggregate. The query plans are represented as a tree of stages, in which each stage passes its results to its parent node. The Spatial module supports the object model of Simple Feature Access in queries and object binding. PLEXIL arrays are homogenous and one-dimensional: a sequence of values of a single scalar data type, indexed by integers beginning with 0. 2 regular expression and replacement metacharacters. Mix of text and element children in many places, but east should have only a text node. But an exception occurs if the aggregate's arguments (and filter_clause if any) contain only outer-level variables: the aggregate then belongs to the nearest such outer level, and is evaluated over the rows of that query. regexpCacheMisses: The number of unsuccessful regular expression cache lookups. Amazon CloudWatch can monitor AWS resources such as Amazon EC2 instances, Amazon DynamoDB tables, and Amazon RDS DB instances, as well as custom metrics generated by your applications and services, and any log files your applications generate. Aggregate support¶ It’s now possible to run SQL aggregate queries (i. 0 was released. archive: A compressed MarkLogic Server database archive created using the mlcp export command. The root Entity can hand references to the internal Entities to other objects, but they can only use them transiently (within a single method or block). 5 rounds the number further away from 0). It contains the following sections: Data types. And it can be quite usable as is in the application in many cases. The operation replaces all existing fields in the input document, including the _id field. Return type is List for above query However the root result expects List and there is no syntax or provision available in Salesforce to specify that child results are of type "AggregateResult". That will add the "HAVING last_name_count >= 3" expression to the query so that, this time, the query only shows actors whose last names appear three or more times in the table:. Functions dealing with attribute dimensions, Children(East) /* Valid in Calc and MDX */ East. An aggregate expression represents the application of an aggregate function across the rows selected by a query. The Criteria API allows us to build up a criteria query object programmatically, where we can apply different kind of filtration rules and logical conditions. The domain service is a query support mechanism for the aggregates. NASA Astrophysics Data System (ADS) Gamon, J. in offline queries for root-cause analysis and system opti-mizations. 1978-01-01. Thus, even if the JSON object that you are querying has only one root element, the FROM clause must begin with S3Object[*]. Using the same expression multiple times in a query projection will crash when using Hibernate SQLMergeClause. You can not use aggregate expressions in sub query. We believe that support for full regular expressions over graph edges is important, particularly if combining provenance data from multiple sources whose attribute names may not be fully consistent. OData (Open Data Protocol) is an ISO/IEC approved, OASIS standard that defines a set of best practices for building and consuming RESTful APIs. However, the root class can be configured so queries on it return only instances of itself, without instances of its subclasses. Built-in functions. The Apache Lucene Project Management Committee decided in a vote, that the Apache Lucene sub-project "Open Relevance" will be discontinued. One of the table functions is pipelined, the other is not. To explicitly or implicitly define a virtual column. These would serve as PostgreSQL input/output functions, with some syntax wrappers around it to support the standard syntax. Only metrics matching any of the prefixes will be retrieved. Several new operators have been added to the algebra to allow support for recursive queries. A major advantage of using the criteria API is that errors can be detected earlier, during compilation rather than at runtime. Thank you, that was perfect. The Java Persistence query language is an extension of the Enterprise JavaBeans query language, EJB QL, adding operations such as bulk deletes and updates, join operations, aggregates, projections, and subqueries. Finite automata-based algorithms suffer from potentially. An xml datum can contain one of two sorts of values: a document or a fragment. The first level focuses on the simplest possible expression of the most common use cases encountered in quality measurement and decision support, while the second level focuses on more advanced capabilities such as multi-source queries and user-defined functions. The expressions that are not encapsulated within an aggregate function and must be included in the GROUP BY clause. As of Spring Data JPA Release 1. To access the value of the variable, use a string with the variable name prefixed with double dollar signs ($$); i. Enter aggregate functions. As such, Druid SQL only has partial support for NULLs. The examples in this topic demonstrate how to use the Average, Count, Max, Min, and Sum methods to query the AdventureWorks Sales Model using query expression syntax. But for those objects that cannot be obtained by navigation, you can use a range variable declaration to designate a starting point, or query root. But there's a little more to it than that, as the COUNT() function can be utilized to count all rows in a table or only those rows that match a particular condition. Write models will be modeled using domain driven design, aggregate roots should correspond to transactional boundaries. This reduces data traffic between your application and database server when you add several queries to the SQLDataSource, but the report uses a single query at a time. Spring Data JDBC assumes that only the aggregate has a foreign key to a table storing non-root entities of the aggregate and no other entity points toward non-root entities. 4 – Common Table Expressions (WITH queries) On 4th of September Tom Lane committed another great patch. Sophocles, Oedipus Rex This chapter describes how to combine the values, operators, and functions described in earlier chapters evaluate to a value. If a column is dynamic partition column, its value will be coming from the input column. 1 Getting Data from the Root Row. 2015-03-01. The ideal condition would be, I admit, that men should be right by instinct. The STDEV function computes the standard deviation of a data set, which is the square root of the VARIANCE function. Executable facts — Unix. Similarly, the expression COALESCE(col1, col2) will return col2 if col1 is an empty string. This tutorial explains various common XPath expressions used to extract data from XML documents. Aggregate support¶ It’s now possible to run SQL aggregate queries (i. The outer query treats the result of the subquery as a table. N1QL now has support for ANSI joins making it easier to migrate applications from relational databases to Couchbase. You can use cursors with FT. Also, this is a performance hit because we have to perform as many queries as there are member statuses. Amazon S3 Select always treats a JSON document as an array of root-level values. DataFrames support convenient ways to query data, either through language-integrated queries or SQL. Learning XPath by Example. For example, a domain service might support a calculation. This last query has a couple of problems: it's inefficient (because of the unions) and it eliminates duplicates in the results, something that would not happen if I applied a single predicate.