Query Workbench

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      The Query Workbench is a user interface tool that can perform query development.

      Using the Query Workbench, you can explore data, create, edit, run, and save SQL++ queries, view and save query results, and explore the document structures in a bucket—​all in a single window.

      Features of the Query Workbench include:

      • A single, integrated visual interface to perform query development and testing.

      • Easy viewing and editing of complex queries by providing features such as multi-line formatting, copy-and-paste, syntax coloring, auto-completion of SQL++ keywords and bucket and field names, and easy cursor movement.

      • View the structure of the documents in a bucket by using the SQL++ INFER command. You no longer have to select the documents at random and guess the structure of the document.

      • Display query results in multiple formats: JSON, table, and tree. You can also save the query results to a file on disk.

      Prerequisites

      The database you’re using must have the Query Service running.

      Accessing the Query Workbench

      Permissions Required

      To view the Query Workbench and run queries that read documents, you need the Database Data Reader project role. To run queries that read and modify documents, you need the Project Owner or Database Data / Reader role.

      To open the Query Workbench in a database running the Query Service:

      1. With the Projects tab in your organization open, click the project with the database you’re working with.

      2. With the Databases tab open, select your database.

      3. Click the Data Tools tab.

      4. In the navigation menu, click Query.

      The Query Workbench consists of three working areas:

      Using the Query Editor

      The Query Editor is where you build and run queries, and view query execution plans. Enter a query into the Query Editor, and then run the query by clicking Execute.

      You can also execute queries by typing a semi-colon (;) at the end of the query and pressing Enter.

      The Query Editor provides the following additional features:

      • Syntax coloring: For easy viewing, SQL++ keywords, numbers, and string literals are differently colored.

      • Support for SQL++ INFER statements: Support the SQL++ INFER statement.

      Specify Bucket and Scope Context

      You can specify the bucket and scope query context using the drop-down menus near the top left of the Query Editor. When the query context is set to a specified bucket and scope, you can write queries using just the collection name and don’t need to specify the keyspace path.

      For example, here’s how a query would look without specifying a bucket and scope in the Query Editor:

      SELECT * FROM `travel-sample`.`inventory`.`airline`;

      If you then specify the bucket as travel-sample and the scope as inventory, the query can be simplified to:

      SELECT * FROM `airline`;

      To specify the query context:

      1. Near the top left of the Query Editor, open the bucket drop-down menu and choose a bucket.

      2. With a bucket now selected, the scope drop-down menu is enabled with the _default scope selected. Using this drop-down, you can choose a different scope within the current bucket.

      To remove the query context, open the bucket drop-down and choose Select a bucket.

      For more information about scopes and collections, refer to Scopes and Collections.

      Run a Query

      After entering a query, you can run it by typing a semicolon (;) and pressing Enter or clicking Execute. When the query is running, the Execute button changes to Cancel, which allows you to cancel the running query. When you cancel a running query, it stops the activity on the database side as well.

      The Cancel button doesn’t cancel index creation statements. The index creation continues on the server side even though it appears to have been canceled from the Query Workbench.

      Run a Transaction

      You can run a Couchbase transaction using the Query Editor. A transaction is a group of operations that are either committed to the database together or are all undone from the database if there’s a failure. For more information about Couchbase transactions, see Transactions.

      You can use the Query Editor to run a single statement as a transaction. To do this, enter the statement into the Query Editor and click Transaction.

      Index Advisor

      The ADVISE command generates index advice that optimizes response time for a query. You can use this command with SELECT, MERGE, UPDATE, or DELETE queries. To display index advice for a query entered into the Query Editor, click Advise.

      Query Workbench shows any suggested indexes in the Query Results area using JSON format. This won’t prepend ADVISE to the current query in the Query Editor

      Viewing the Query Results

      When you execute a query, the results are in the Query Results area. Since large result sets can take a long time to display, it’s recommended that you use the LIMIT clause as part of your query when appropriate.

      The figures in this section display the result of the following query:

      SELECT * FROM `travel-sample` WHERE type="airport" LIMIT 1;

      When a query finishes, metrics for that query appear between the Query Editor and the Query Results areas.

      The executed query with its metrics highlighted.

      The following query metrics are shown with the query results:

      Status

      Shows the status of the query. The values can be success, failed, or HTTP codes.

      Last Run

      The time at which the query was last executed.

      Round-trip time (RTT)

      The total time it took to send the request and receive the response from the server.

      Elapsed

      The time taken by the server to process the request.

      Execution

      The time taken by the server to execute the query.

      Docs

      The number of documents returned.

      Mutation Count

      The number of documents deleted or changed by the query. This appears for UPDATE and DELETE queries instead of Result Count.

      Size

      The total size, in bytes, of the documents returned.

      JSON Format

      The JSON tab formats the results to make the data easy to read. You can also expand and collapse objects and array values using the small arrow icons next to the line numbers.

      If you clicked Execute, the results of the query are shown. If you clicked Explain, the results are the same as Plan Text format.
      The Query Results area with the 'JSON' tab selected.

      Table Format

      The Table tab presents the results in a tabular format. The tool converts the JSON documents to HTML tables and presents sub-objects or sub-arrays as sub-tables. This format works well for queries that return an array of objects, like select `beer-sample`.* from `beer-sample`;. You can hover the mouse pointer over a data value to see the path to that value in a tooltip. You can sort a column by clicking the column header.

      The Query Results area with the 'Table' tab selected.

      Plans

      Each time you execute a query, an EXPLAIN command is automatically run in the background to retrieve the query plan for that query. You may also generate the query plan by clicking Explain.

      The two ways to display the query plan are Plan (graphical) and Plan Text.

      Plan

      The Plan tab presents the query in a graphical format.

      At the top, it shows a summary which also shows lists of the buckets, indexes, and fields used by the query.

      At the bottom is a data-flow diagram of query operators, with the initial scans at the right, and the final output on the left.

      Potentially expensive operators are highlighted.

      The data flow generally follows these steps:

      1. Scan

      2. Fetch

      3. Filter

      4. Projection (part 1)

      5. Order

      6. Projection (part 2)

      Projection is split into two parts (one before Order and one after Order), but Query Workbench shows only the first part.
      The Query Results area with the 'Plan' tab selected.

      Hovering over any unit of the plan shows more details of it. In this example query:

      Unit name Information shown when hovered over

      Order

      {'#operator':'Order':'sort_terms':
      [{'expr':'(`travel-sample`.`name`)'}]}

      Project

      {'#operator':'InitialProject':'result_terms':
      [{'expr':'self','star':true}]}

      Filter

      {'#operator':'Filter','condition':'(((`travel-sample`.`type`) = \'landmark\') and
      ((`travel-sample`.`city`) = \'San Francisco\'))'}

      Fetch

      {'#operator':'Fetch','keyspace':'travel-sample','namespace':'default'}

      IntersectScan

      (none)

      IndexScan2 (above)

      {'#operator':'IndexScan2','index':'def_city','index_id':'d51323973a9c8458','index_projection':
      {'primary_key':true},'keyspace':'travel-sample','namespace':'default','spans':
      [{'exact':true,'range':[{'high':'\San Francisco\'','inclusion':3,'low':'\'San Francisco\''}]}],'using':'gsi'}

      IndexScan2 (below)

      {'#operator':'IndexScan2','index':'def_city','index_id':'a11b1af8651888cf','index_projection':
      {'primary_key':true},'keyspace':'travel-sample','namespace':'default','spans':
      [{'exact':true,'range':[{'high':'\'landmark'\'','inclusion':3,'low':'\'landmark\''}]}],'using':'gsi'}

      In general, the preference of scan is

      1. Covering Index

      2. Index Scan

      3. Intersect Scan

      4. Union Scan, and finally

      5. Fetch

      Plan Text

      The Plan Text tab shows the EXPLAIN query execution plan in JSON format.

      If you chose Execute, a detailed query execution plan appears with information about how long each step in the plan took to execute. If you chose Explain, the intended query execution plan appears without the details that an executed query includes.

      The Query Results area with the 'Plan Text' tab selected.

      View Query History

      The Query Workbench maintains a history of all the queries executed.

      If you edit a previous query and execute it, the new query is stored at the end of the history. The history is persistent across browser sessions. The query history saves queries; due to limited browser storage, it doesn’t save query results. Thus, when you restart the browser or reload the page, you can see your old queries, but you must re-execute the queries if you want to see their results.

      Clearing the browser history clears the history maintained by the Query Editor as well.

      Clicking History opens the Query History fly-out menu:

      The 'Query History' fly-out menu.

      You can scroll through the entire query history, and click an individual query to view that particular point in the history.

      • Search history: You can search the query history by entering text in the Filter Queries search box. All matching queries are displayed.

      • Delete a specific entry: Click the Trash icon next to a particular query to delete it from the history.

        This can be useful if you want a more manicured history when you export the history for future use.
      • Delete all entries: Click Clear to delete the entire query history.

      Import Queries

      You can load a new query history into the Query Workbench from a JSON file. This can be the exported query history from a different database.

      Importing query history overwrites your current query history.
      1. From the database’s Data Tools  Query page, click History.

        This opens the Query History fly-out menu.

      2. Click Import.

        This opens the Import Query History fly-out menu.

      3. Click Choose a File and select a local .json file that you wish to import.

      4. Click Import Queries.

        The preexisting query history is overwritten with the query history of the imported file.

      Export Query History

      You can export the current query history to a JSON file, which you import into other databases.

      1. From the database’s Data Tools  Query page, click History.

        This opens the Query History fly-out menu.

      2. Click Export.

        This opens the Export Query History fly-out menu.

      3. (Optional) Use the File Name field to specify a name for the exported file.

      4. Click Export.

        The fly-out menu closes and the file downloads to your computer.

      Modify Query Settings

      You can specify various settings for the Query Workbench by clicking Settings near the top-left corner of the Query Editor. This opens the Query Settings fly-out menu.

      Configure the following settings and click Submit to save the configuration.

      Option Description

      Timeout

      The timeout parameter in seconds limiting the running time of a query. You can set this to a maximum of 1800 seconds

      Scan Consistency

      This is a cbq-engine option. Select one of the following options:

      • Not Bounded

      • Request Plus

      • Statement Plus

      For more information, refer to Settings and Parameters in the Couchbase Server documentation.

      Transaction Timeout

      Specifies the maximum time in seconds spent on a transaction before timing out.

      Named Parameters

      For the prepared queries, this option allows you to specify any number of named parameters. Click the + button to add new named parameters, and the - button to remove the parameters. Named parameters must start with the dollar sign ($) for use in prepared queries. Otherwise, they are interpreted as parameters to the Query REST API.

      Positional Parameters

      For the prepared queries, this option allows you to specify values for $1, $2, and so on up to as many positional parameters as you have. Click the + button to add new positional parameters, and the - button to remove the parameters. The parameters are automatically labeled as "$1", "$2", and so on.

      Data / Bucket Insights

      The Data Insights area displays the buckets, scopes, and collections in the current database. These keyspaces are in a hierarchy that you can expand or collapse.

      • To expand a heading within the hierarchy, click the heading, or click the rightward-pointing arrowhead before the heading.

      • To collapse a heading within the hierarchy, click the heading again, or click the downward-pointing arrowhead before the heading.

      Buckets appear at the top level of the hierarchy. When you expand a bucket, the scopes within that bucket appear below it. Similarly, when you expand a scope, the collections within that scope appear below it. The number of collections within the bucket is displayed to the right of the bucket heading.

      The 'Data Insights' panel.