| Download Docs | Site Map | Glossary | |
|
|
|||
| bea.com | products | dev2dev | support | askBEA |
|
|
|
|||||||
 |
| e-docs > Liquid Data for WebLogic > Building Queries and Data Views > Data View Builder GUI Tour |
|
Building Queries and Data Views
|
The Data View Builder consists of three main views or modes that you can get to by clicking on the associated tabs. Each tab represents a phase in the process of designing and testing a query. Generally, you will use the Design and Test tabs to design and run (test) the query, respectively. Some, but not all, queries will require the use of optimization hints and techniques on the Optimize tab.
The Design tab is where you construct the query by working with source and target schemas to specify source conditions and source-to-target mappings.
The following sections describe the features available on the Design tab.
Overview Picture of Design Tab Components
The following figure and accompanying sections describe the components on the Design tab. (Click the tab to access it.)
Note: Although not entirely specific to the Design tab, the menus, horizontal shortcut toolbar and status bar are also covered in detail in this section since this is the first place you encounter them. Although some menu options and toolbar shortcut buttons do stay the same regardless of which tab you are on, there are mode-specific menus and toolbar options for Design, Optimize, and Test tabs which are explained in those topics.
1. Menu Bar for the Design Tab
The menus provide File, Schema, View, and Window menus as detailed in Table 2-1.
|
Provides Project-related actions (creating a new project, saving a project, and so on) along with an Exit option that closes the Data View Builder application. For more information on working with projects in the Data View Builder, see Working With Projects.
|
|
|
Provides standard edit features. These are activated or deactivated depending on what is selected on the User Interface. For example, you can delete a node in a schema so when any schema node is selected "Delete" is active. |
|
|
As an alternative to using the tabs the View menu lets you navigate to the following UI views:
To help with screen real estate and workspace, the View menu provides toggles to show or hide various windows, tools, and tabs in the Design view. You can show or hide the following:
On the menu, an "x" by an option indicates it is currently displayed. By default, all tools, windows and tabs are shown when you first open the Data View Builder. |
|
For a description of the other options in the Query menu (Run or Stop Query Execution) which are relevant only for running/testing a query, see Table 2-3. |
|
|
The Window menu provides various options for window management: As you open source schema windows they are listed in the Window menu so that you choose an open schema from the menu to navigate to it. |
|
|
Provides online documentation for the Data View Builder. Note: For this release Liquid Data, the online help for the Data View Builder simply links into the main topics in online documentation for the Data View Builder. |
The toolbar, located directly below the menus, provides shortcuts to a subset of commonly used actions also available from the menus.
The Builder Toolbar includes two subtabs:
The Sources tab on the Builder Toolbar contains the data sources configured on the Liquid Data Server to which you are connected. Note that a data source type only shows up as a button on the Builder Toolbar if it has been configured in the Server to which you are connecting.
Note: For a detailed introduction to these data sources, see Different Kinds of Data Sources in Overview and Key Concepts.
To open a schema for a data source, click on the data source type (for example Relational Databases) to get a list of configured data sources of that type. Then double-click on the particular data source you want to work with The schema window for that source is displayed in a movable window on the Liquid Data desktop.
Figure 2-4 Builder Toolbar: Sources Tab
The Toolbox tab on the Builder Toolbar provides the following tools to use in query construction:
Note: Any custom functions configured in the Liquid Data Server through the WebLogic Server Administration Console will show up on the Builder Toolbar on the Functions panel along with the standard functions provided.
Figure 2-5 Builder Toolbar: Toolbox Tab
XQuery Functions are built-in code modules that return a value when they run. The XQuery Functions panel provides a library of standard W3C functions compliant with the W3C XQuery 1.0 and XPath 2.0 Functions and Operators specification. (See Figure 2-5 for an example of the Functions panel on the Builder Toolbar Toolbox tab.)
In Data View Builder, the Functions are displayed in the Builder Toolbar on the Toolbox tab XQuery Functions panel by category names like Aggregate Functions, Boolean Functions, Cast Functions, and so on. To view all the functions in a category or group, expand the group node.
You can double click or drag and drop a function object to the Liquid Data desktop where it appears in a tree format showing the number and type of parameters required.
A copy of any mapped function saves automatically with the project when you close it. The saved function (with associated parameters) appears in the Components panel when you reopen the project. If you do not map the new function and you terminate the session, Data View Builder discards it and it does not appear in the Components panel.
Each function has a specification for required parameters and expected behavior. Some functions cannot be used in the work area, but must appear only on the desktop. For complete information about each function, its parameters, and expected behavior, see Functions Reference. For more detailed information, see the W3C XQuery 1.0 and XPath 2.0 Functions and Operators specification.
The functions editor gives you a space to create functions using drag-and-drop and to view existing functions in your project.
There are two ways to open the Functions Editor:
Figure 2-7 Click Edit Button to Get the Functions Editor
If you have custom functions configured through the Administration Console, these will show up in the Data View Builder on the Toolbar Functions tree in a custom group. The name of the group is what you specify in the "presentation group" element in the custom functions library definition (.CFLD) file. If no grouping label is specified "Ungrouped". For more information on this, see "Contents of a CFLD File" and "Structure of a CFLD File" in Using Custom Functions in Invoking Queries Programmatically.
You can use the Constants panel to create function parameters with constant values.
Figure 2-8 Builder Toolbar: Toolbox Tab: Constants
Choose the type of constant based on how you want the data to be considered in the query. Strings are alphanumeric values that typically contain alphabetic letters, special characters, and digits used in non-numeric comparisons. Names, zip codes, phone numbers, and street addresses are typical examples of string values.
Numbers can be integers (positive or negative), decimal values, or floating point expressions. The Empty element enables you to force an element to appear in the query. We expect mapped data elements to appear in the query result, but you may wish to see other data elements appear that are not mapped. If you drag and drop the Empty element onto a node, that node will appear in the query result.
To include a String, Number, or Empty element constant as a function parameter, follow steps similar to those shown in this example:
xf:starts-with(str1,str2)
The condition appears in the Functions Editor as shown in the following figure.
Figure 2-9 Condition with starts-with Constant in Functions Editor
Close the Functions Editor by clicking the Close button. The new condition you created is also now displayed in the Source column on the Condition tab.
Figure 2-10 Condition with starts-with Constant in Row on Conditions Tab
Note: If you design a query with a constant, and then design another query using a query parameter that specifies exactly the same value, the generated XQuery translation is different even though the functionality in each query is exactly the same.
Query parameters can be strings, integers, floating point numbers, boolean expressions, or date and time types. They are variables that you define with no static value. On the Test tab, you can supply a different value each time you run the query (see 4. Query Parameters: Submitted at Query Runtime).
The Query Parameter section of the Toolbox provides a text box where you can enter a new parameter value to be stored.
You can invoke these variables when you build conditions. As a convenience, you can:
Table 2-2 describes supported simple query parameter data types.
To use a simple query parameter, drag and drop a parameter from the Query Parameter resource area to the appropriate item of source data. Then, when you run your query, a window will appear where you can enter your test parameter.
To see use of a simple query parameter, please see the Order Query demo, available from the Liquid Data documentation home page.
http://download.oracle.com/docs/cd/E13190_01/liquiddata/docs10/interm/demopage.html
Note: If you design a query with a constant, and then design another query using a query parameter, the generated XQuery translation is different even though the functionality in each query is exactly the same.
The Components panel shows the structure of the current project in Design View. All elements of the query, except the target schema appear in this view of the project, including any data source schemas you are using or functions that you map with parameters.
If a particular component schema is unavailable when a project is re-opened, the schema will still be listed, but it will be flagged as unavailable (off-line) and a red mark will appear over the schema name.
Figure 2-12 Builder Toolbar: Toolbox Tab: Components
Any component that appears in this panel can be minimized on the Liquid Data desktop by double clicking the appropriate node. Click again and the component reappears on the desktop. The target schema does not appear in the Components panel because you cannot close it while working on the project.
When you save a project by name and reopen it, the project components appear in this window, but minimized on the desktop. You can move them to the desktop by double clicking a selected component. When you reopen a saved project, the output schema appears directly on the desktop instead of in the Components tree.
You can right-click any parent node and click Edit, Delete, or Rename to complete those tasks.
Source schema windows show XML schema representations of the structure of the data in the selected data source. Used to create source conditions and mappings to a target schema. You can have multiple data source schemas open on the Liquid Data desktop as needed.
Note: For a detailed description of the special characters used to identify characteristics of schema nodes, see Special Characters: Occurrence Indicators.
To open a schema for a data source:
The Target Schema window shows the XML schema representation for the structure of the target data (query result).
Only one target schema per project is allowed. If you have a target schema open and decide to choose another, the current target schema is closed and the new one replaces it.
Note: For a detailed description of the special characters used to identify characteristics of schema nodes, see Special Characters: Occurrence Indicators.
To open and set a target schema for a project:
(You can also choose the menu item File—>Set Selected Source Schema as Target Schema to add a source schema selected on the Builder Toolbar as the target schema.)
The Conditions area functions both as a tracking and reflection tool, and as a workspace that you can manipulate directly. Whenever you do a drag-and-drop operation that causes an update to Conditions, the Conditions tab is automatically displayed.
Figure 2-15 Conditions Tab on the Design tab
The Conditions section shows conditions (filters) for source data. As you build up the query by creating drag-and-drop source-to-source node relationships among data source schemas, the implied condition statements are recorded and reflected as joins under the Conditions. Even if you don't drag and drop anything directly into the Conditions tab, you will see the appropriate conditions building up here as a result of your work with the source schemas. (When you drag and drop a source element onto another source element, the equals function is used by default to create a simple join.)
Figure 2-16 Conditions Tab in Basic View
You can also use the Conditions area as a workspace to explicitly drag-and-drop elements of a query statement into the rows under Conditions to build up the query. You can drag-and-drop elements and attributes from source schemas as well as functions, constants, and parameters from the Builder Toolbar "Toolbox" tab directly into the rows under Conditions to craft conditions statements.
This tab includes the following features to facilitate working with conditions:
Advanced View for Defining Explicit Scope for Conditions
When you click the Advanced View toggle, the Conditions tab displays a column for defining explicit scope for each condition.
Figure 2-17 Conditions Tab in Advanced View Showing Explicit Scope
The Scope area on the Conditions tab shows any explicit narrowing conditions (filters) you define for the target data to refine the query result. In basic mode (with Advanced toggle off) Data View Builder creates queries based on the scope implied by the source conditions you create and the structure of the target schema (implicit scope). In other words, by default the implicit scope is auto-generated by the Data View Builder. The auto-generated, implicit scope should be sufficient for most cases. However, there may be situations in which you want to control scoping explicitly. In these cases, you can switch to the Advanced view.
A scope setting affects the placement of a where clause in the XQuery generation. The Data View Builder best guess at implicit scope will satisfy most cases, and you will generally not have to specify scope. For cases where you need to explicitly define scope to force the where clause to the right place in the query or sometimes to force it to be there at all, you can do this directly by dragging the appropriate node in the target schema into a row under Scope.
For more information and examples about when and how to set scope, see Understanding Scope in Basic and Advanced Views in Designing Queries.
Returning to Basic View (Automated Scope)
When you toggle Advanced View off (no X showing next to Advanced View), Data View Builder returns to automatic scoping mode and discards the changes you made in manual mode. The Current Scope text box and the Targets column disappear.
The Mappings tab shows source-to-target mappings that will define the structure of the query result. As you drag-and-drop source elements onto target elements among the schema windows, the Mappings tab records these relationships, which build up the shape the data will take in the query result. For example, dragging and dropping FIRST_NAME and LAST_NAME elements from CUSTOMER in a source schema to the associated CUSTOMER elements in the target schema specifies that in the query result customers will be identified with first and last names as defined.
Whenever you do a drag-and-drop operation that causes an update to Mappings, the Mappings tab is automatically displayed.
To delete a mapping, select the row on the Mappings tab that contains the source-to-target mapping you want to delete (selected mapping is highlighted) and click the trashcan.
The Sort By tab specifies how the result should be ordered and a list of candidate nodes that you can order. Figure 2-19 shows the order of a repeatable node segment of the target schema. The drop-down list shows all repeatable data nodes in the target schema marked with an asterisk (*) or a plus sign (+). A repeatable node is the parent of child nodes that can appear in the query result once for every instance of a match. A repeatable node is an ancestor to one or more nodes that will represent unique data returned by the query.
The blue arrows move rows up and down. These icons are enabled only when you select a data item that can move up or down. The drop-down list shows the repeatable nodes with subordinate nodes that can be sorted. When you select a repeatable node from the drop-down list, the associated child nodes appear in the Sort By list. Move these child nodes up or down to specify how the result should be sorted. For example, a Customer* element can be sorted first by Last_name and then by First_name by having the Last_name row at the top and the First_name row directly beneath it.
An item can be moved if it is assigned an ascending or descending attribute in the source schema. (The database administrator or data architect who creates the source schema specifies this.) Items with ascending or descending attributes can be moved up only if there is another item above, and they can be moved down only if the next item down also has an ascending or descending attribute.
The Status Bar is a horizontal bar at the bottom of the Data View Builder that provides status information about current actions and processes.
The Optimize tab is where you can optionally add more information such as "hints" to data sources to improve query performance.
The following sections describe the features available on the Optimize tab.
Overview Picture of Optimize Tab Components
The following figure and accompanying sections describe the components on the Optimize tab. (Click the tab to access it.)
Note: The Optimize tab contains a subset of the menu options and toolbar buttons available on the Design tab. For a full description of these options, see 1. Menu Bar for the Design Tab and 2. Toolbar for the Design Tab.
You can re-order source schemas on the top frame on the Optimize tab to improve query performance. To move a schema up or down, select the schema and click the up or down arrow buttons to the right of the list of schemas.
When a query uses data from two sources, the Liquid Data Server brings the two data sources into memory and creates an intermediate result (cross-product) using the two sources. If you specify more than two sources, the Liquid Data Server creates a cross-product of the first two sources, then continues to integrate each additional resource, one at a time, in the order that they appear in FOR clauses. The intermediate result grows with each integration, until all sources are accounted for.
The size of a source is the number of tuples, or records, used in the query from that source. The size of the intermediate result depends on the input size of the first source multiplied by the input size of the second source and so on. A query is generally more efficient when it minimizes the size of intermediate results. You can re-order source schemas in certain situations to improve performance.
For detailed information on how to optimize a query by ordering source schemas, see Optimizing Queries.
A query hint is a way to supply more information to the Liquid Data Server about the amount of data each source contains when processing a query. The Join Hints frame contains a drop-down list of data source pairs, and a table that shows all the joins for each pair. Only source pairs that have join conditions across them appear in the drop-down list. For each join condition in the table, you can provide a hint about how to join the data most efficiently.
For detailed information on how to optimize a query by using optimization hints, see Optimizing Queries.
The Test tab is where you view the generated XQuery language interpretation of the query elements you developed on the Design and Optimize tabs, and run the query against your data sources to verify the result and evaluate performance.
From this view, you can provide different parameters to the query before you run it.
The following sections describe the features available on the Test tab.
Overview Picture of Test Tab Components
The following figure and accompanying sections describe the components on the Test tab. (Click the tab to access it.)
|
Provides most of the same options as shown on the Design tab menu bar with one additional menu option as follows:
For a description of the other File menu items available from the Test tab (which are a subset of those on the File menu for the Design tab), see Table 2-1 in Design Tab |
|
|
Provides the following options related to running a query:
The Query menu options for Automatic Type Casting and Condition Targets—>Advanced View are more relevant to designing a query and, therefore, are described in 1. Menu Bar for the Design Tab. |
The toolbar, located directly below the menus, provides shortcuts to a subset of commonly used actions also available from the menus.
Figure 2-23 Toolbar on the Test Tab
The query you developed on the Design and Optimize tabs is shown in XQuery language in the "Query" window on the upper left panel on the Test tab.
Figure 2-24 Builder-Generated XQuery Shown in Query Window
4. Query Parameters: Submitted at Query Runtime
You can use the Query Parameters panel to add variable values to a query each time you run it. The list of variables depends on the number of variables you defined as Query Parameters on the Design tab (see Query Parameters: Defining) and which ones appear as one or more function parameters.
Figure 2-25 Query Parameters Settings on Test Tab
5. Query Results - Large Results
If you anticipate a large set of data coming back in the query result, click Large Results (an X in the box indicates this feature is on). The default is off (no X).
When this option is on, Liquid Data uses swap files to temporarily store results on disk in order to prevent an out-of-memory error when the query is run.
Figure 2-26 Specifying Large Results
To run a query, click the Run Query button on the toolbar in the upper left of the Test tab. (You can also choose the Run Query option from the Query menu.)
Figure 2-27 Click the "Run Query" Button to Run the Query
The query is run against your data sources and the result is displayed in the Results panel in XML format.
You can stop a running query before it has finished processing by clicking the Stop Query Execution button in the toolbar. (You can also choose the Stop Query option from the Query menu.)
Figure 2-28 Click the "Stop Query Execution Button" to Stop a Running Query
When you run a query, the result is displayed in the Results window on the Test tab in XML format.
Figure 2-29 Query Result is Shown on Test Tab When Query is Run
|
|
|
|
||
 |
|
|
 |
 |
 |
|
||
