Configuring an Advanced Refresh Job

Using cron expressions, you can specify a more complicated schedule for refresh jobs for the data cached for a data source configuration.

To configure an advanced refresh job for a data source configuration using a cron expression:

  1. Make sure you are logged in as a Zoomdata administrator.

  2. Select (Settings) and then select Sources. The Data Sources page appears.

  3. In the My Data Sources table on the Data Sources page, locate and select the data source configuration you want to edit. The data source configuration wizard appears.

  4. Select the Refresh tab. Make sure the Schedule subtab is selected.

  5. Select the Advanced option at the top of the Refresh tab. The settings for an advanced refresh job appear.

  6. In the box provided, enter a cron expression that sets the schedule using a string of six fields, each separated by a blank space. The format for the cron expression is:

    <seconds> <minutes> <hours> <days of the month> <months> <days of the week>

    The standard values supported by each field include:

    Field Allowed Values Additional Characters
    <seconds> 0-59 , - * /
    <minutes> 0-59 , - * /
    <hours> 0-23 , - * /
    <days of the month> 1-31 , - * / ? L W
    <months> 1-12 or Jan-Dec , - * /
    <days of the week> 1-7 or Sun-Sat , - * / ? L W #

    When creating the cron expression, keep the following requirements in mind:

    • Specifying <seconds> is optional, but defaults to zero seconds, which ensures that only one refresh job is run. If you specify seconds, the refresh job is rerun after that number of seconds has elapsed.

    • Either the <days of the month> or <days of the week> field is needed, but both should not be specified. If one of these fields is marked with an asterisk (*), the other is automatically set to a question mark in the cron expression. In addition, an error is returned if you try to specify both of these fields.

      If you save an existing data source configuration that has both fields specified, no error is returned, but warnings are written to the log when Zoomdata starts.
    • Names for the <month> and <days of the week> fields are not case sensitive. For example, FRI and fri are both acceptable formats.

    Special characters that can be specified are described in the table below.

    Special Character What It Means

    All values. Represents all the values within the specified field. In the following example, an asterisk is used in the <minutes> field, indicating that the job will run every minute:

    0  *  0  0  0  0

    No specific value. Used as a placeholder when no value is needed in the field. In the following example, the <months> field value is 6 (June) and the <days of the week> field value is a question mark, indicating that job runs in June, regardless of the day of the week:

    0  0  0  0  6  ?

    Used to specify a range of values. For example, specifying 3-6 in the <hours> field (as shown in the following example) means the job will run at 3:00, 4:00, 5:00 and 6:00 am:

    0  0  3-6  0  0  0

    Used to specify a series of values. Use the comma to identify all the values for the field. In the following example, a comma is used in the <days of the week> field to run the job on Wednesdays, Thursdays, and Fridays:

    0  0  0  0  0  Wed,Thur,Fri

    Used to specify the starting time value and the incremental increase of time. In the following example, specifying 0/5 in the <minutes> field means that the job runs immediately and then every 5 minutes.

    0  0/5  0  0  0  0

    Last. Used only in the <days of the month> and <days of the week> fields.

    When this character is used standalone, it indicates the last day of the month or the last day of the week (Saturday).

    However, when it is used with a value (such as 5L) in the <days of the month> field, it means the last Friday of the month (5 is Friday, L indicates the last Friday).

    0  0  0  5L  0  0

    Weekday. Used only in the <days of the month> and <days of the week> fields.

    Identifies the weekday closest to the given day. For example, 15W means the closest weekday to the 15th of the month. The following results are possible:

    • If the 15th falls on a Saturday, the result returned would be Friday the 14th
    • If the 15th falls on a Sunday, the result is Monday the 16th
    • If the 15th falls on a weekday, that specific day is returned.

    Number sign. Used only with the <days of the week> field.

    Identifies the specific day of the month. For example, both Wed#2 and 3#2 identify the second Wednesday of the month.

    0  0  0  0  0  Wed#2

    The following table provides some cron expression examples:

    cron Expression Meaning
    0  0  12  *  *  ?
    Noon every day
    0  30  20  ?  *  *
    8:30 p.m. every night
    0  0/10  17  *  *  ?
    Every 10 minutes starting at 5 p.m. and ending at 5:50 p.m., every day
    0  15-30  20  *  *  ?
    Every minute starting at 8:15 p.m. and ending at 8:30 p.m., every day
    0  45  20  ?  *  Mon,Wed,Fri
    8:45 p.m. every Monday, Wednesday and Friday
    0  0  20  3/3  *  ?
    8 p.m. every 3 days in every month, starting on the third day of the month
  7. When your changes are complete, click , , or (depending on the tab) to save the data source configuration and close the wizard.