Authoring and running queries - Amazon Redshift

Authoring and running queries

You can enter a query in the editor or select a saved query from the Queries list and choose Run.

By default, Limit 100 is set to limit the results to 100 rows. You can turn off this option to return a larger result set. If you turn off this option, you can include the LIMIT option in your SQL statement if you want to avoid very large result sets. For more information, see ORDER BY clause in the Amazon Redshift Database Developer Guide.

To display a query plan in the results area, turn on Explain. Turn on Explain graph for the results to also display a graphical representation of the explain plan.

To save a query to the Queries folder, choose Save.

For a successful query, a success message appears. If the query returns information, the results display in the Results section. If the number of results exceeds the display area, numbers appear at the top of the results area. You can choose the numbers to display successive pages of results.

You can filter and sort Result for each column. To enter filter criteria in the result column header, hover over the column to see a menu ( 
                    Filter menu
                ) where you can enter criteria to filter the column.

If the query contains an error, the query editor v2 displays an error message in the results area. The message provides information on how to correct the query.

You can export or copy the results of your query by using the context (right-click) menu in the results area as follows:

  • Choose Export result set and either JSON or CSV to download the entire set of row results to a file. The number of rows in the result set might be limited by the Limit option or the SQL limit clause in the query. The maximum size of the downloaded result set is 5 MB.

  • If no rows are selected, then choose Export current page and either JSON or CSV to download the rows from the current page to a file.

  • If rows are selected, then choose Export selected rows and either JSON or CSV to download the rows that are selected to a file.

  • If rows are selected, then choose Copy rows to copy the selected rows to the clipboard.

  • If rows are selected, then choose Copy rows with headers to copy the selected rows with column headers to the clipboard.

You can also use the shortcut Ctrl+C on Windows or Cmd+C on MacOS to copy data from the current results page to the clipboard. If no rows are selected, then the cell with focus is copied to the clipboard. If rows are selected, then the selected rows are copied to the clipboard.

To add a new query tab, choose the 
                    New query tab
                icon, then Editor, which appears in the row with the query tabs. The query tab is either using an Isolated session or not. With an isolated session, the results of a SQL command, such as creating a temporary table in one editor tab, are not visible in another editor tab. When you open an editor tab in query editor v2, the default is an isolated session.

To run a query

  1. In the query area, do one of the following:

    • Enter a query.

    • Paste a query that you copied.

    • Choose the Queries folder, open the context menu (right-click) a saved query, and choose Open query.

  2. Confirm that you chose the correct Cluster or Workgroup, and Database value for the SQL you plan to run.

    Initially, you can choose your Cluster or Workgroup in the tree view. Choose your Database in the tree view also.

    You can change the Cluster or Workgroup, and Database within each editor tab with the drop-down control located near the Isolated session header of each editor tab.

    For each editor tab, you choose whether to run the SQL in an Isolated session. An isolated session has its own connection to a database. Use it to run SQL that is isolated from other query editor sessions. For more information about connections, see Opening query editor v2.

  3. Choose Run.

    The Result area opens and displays the query results.

To display the explain plan for a query

  1. Select the query.

  2. Turn on Explain.

    By default, the Explain graph is also on.

  3. Choose Run.

    The query runs and the explain plan displays in the query Result area.

The query editor v2 supports the following features:

  • You can author queries with multiple SQL statements in one query tab. The queries are run in serially and multiple results tabs open for each query.

  • You can author queries with session variables and temporary tables.

  • You can author queries with replaceable parameters designated by ${parameter}. You can author your SQL query with multiple replaceable parameters and use the same parameter in multiple places in your SQL statement.

    When the query runs, a window is presented to enter the value of the parameter. Each time you run the query, the window is presented to enter your parameter values.

    For an example, see Example: Sales greater than a specific parameter.

  • Queries are versioned automatically. You can choose an earlier version of a query to run.

  • You don't need to wait for a query to complete before continuing on with your workflow. Your queries continue to run even if you close the query editor.

  • When authoring queries, automatic completion of schema, table, and column names is supported using a shortcut.

    Choose the 
                            Shortcuts
                        Shortcuts icon to find the Auto complete shortcut.

The following examples demonstrate some of these features.

Query examples

Following, you can find descriptions of the various types of queries that you can run.

The data used in many of these queries is from the tickit sample schema. For more information about the tickit data, see Loading sample data.

When you run these example queries, confirm that you choose the correct database in the editor, such as sample_data_dev.

Example: Setting session variables

The following command sets the search_path server configuration parameter to public for the session. For more information, see SET and search_path in the Amazon Redshift Database Developer Guide.

set search_path to public;

Example: Top event by total sales

The following query finds the event with the most sales.

select eventname, count(salesid) totalorders, sum(pricepaid) totalsales from sales, event where sales.eventid=event.eventid group by eventname order by 3;

Following is a partial list of the results.

eventname totalorders totalsales White Christmas 20 9352 Joshua Radin 38 23469 Beach Boys 58 30383 Linda Ronstadt 56 35043 Rascal Flatts 76 38214 Billy Idol 67 40101 Stephenie Meyer 72 41509 Indigo Girls 57 45399 ...

Example: Sales greater than a specific parameter

The following query finds sales where the quantity sold is greater than the parameter specified by ${numberoforders}. When the parameter value is 7, the result is 60 rows. When you run the query, the query editor v2 displays a Run query form window to gather the value of parameters in the SQL statement.

select salesid, qtysold from sales where qtysold > ${numberoforders} order by 2;

Following is a partial list of the results.

salesid qtysold 20005 8 21279 8 130232 8 42737 8 74681 8 67103 8 105533 8 91620 8 121552 8 ...

Example: Create a temporary table

The following statement creates the temporary table eventsalestemp by selecting information from the sales and event tables.

create temporary table eventsalestemp as select eventname, count(salesid) totalorders, sum(pricepaid) totalsales from sales, event where sales.eventid=event.eventid group by eventname;

Example: Selecting from a temporary table

The following statement selects events, total orders, and total sales from the temporary table eventsalestemp, ordered by total orders.

select eventname, totalorders, totalsales from eventsalestemp order by 2;

Following is a partial list of results.

eventname totalorders totalsales White Christmas 20 9352 Joshua Radin 38 23469 Martina McBride 50 52932 Linda Ronstadt 56 35043 Indigo Girls 57 45399 Beach Boys 58 30383 ...

Considerations for querying

Consider the following information about working with queries when you use the query editor:

  • The maximum query result size is the smaller of 5 MB or 100,000 rows.

  • You can run a query up to 300,000 characters long.

  • You can save a query up to 30,000 characters long.

  • You can't use transactions in the editor. For more information about transactions, see BEGIN in the Amazon Redshift Database Developer Guide.