Scheduling a snapshot - Amazon Redshift
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Amazon Redshift will no longer support the creation of new Python UDFs starting November 1, 2025. If you would like to use Python UDFs, create the UDFs prior to that date. Existing Python UDFs will continue to function as normal. For more information, see the blog post .

Scheduling a snapshot

To precisely control when to take a snapshot, you can create a snapshot schedule for specific namepsaces. When scheduling snapshot creation, you can create either a one-time event or use Unix cron expressions to create a recurring schedule. Cron expressions support three fields and are separated by white space.

cron(Minutes Hours Day-of-month Month Day-of-week Year)
Fields Values Wildcards

Minutes

0–59

, - * /

Hours

0–23

, - * /

Day-of-month

1–31

, - * ? / L W

Month

1–12 or JAN-DEC

, - * /

Day-of-week

1–7 or SUN-SAT

, - * ? L #

Year

1970–2199

, - * /
Wildcards

  • The , (comma) wildcard includes additional values. In the Day-of-week field, MON,WED,FRI would include Monday, Wednesday, and Friday. Total values are limited to 24 per field.

  • The - (dash) wildcard specifies ranges. In the Hour field, 1–15 would include hours 1 through 15 of the specified day.

  • The * (asterisk) wildcard includes all values in the field. In the Hours field, * would include every hour.

  • The / (forward slash) wildcard specifies increments. In the Hours field, you could enter 1/10 to specify every 10th hour, starting from the first hour of the day (for example, the 01:00, 11:00, and 21:00).

  • The ? (question mark) wildcard specifies one or another. In the Day-of-month field you could enter 7, and if you didn't care what day of the week the seventh was, you could enter ? in the Day-of-week field.

  • The L wildcard in the Day-of-month or Day-of-week fields specifies the last day of the month or week.

  • The W wildcard in the Day-of-month field specifies a weekday. In the Day-of-month field, 3W specifies the day closest to the third weekday of the month.

  • The # wildcard in the Day-of-week field specifies a certain instance of the specified day of the week within a month. For example, 3#2 would be the second Tuesday of the month: the 3 refers to Tuesday because it is the third day of each week, and the 2 refers to the second day of that type within the month.

    Note

    If you use a '#' character, you can define only one expression in the day-of-week field. For example, "3#1,6#3" is not valid because it is interpreted as two expressions.

Limits

  • You can't specify the Day-of-month and Day-of-week fields in the same cron expression. If you specify a value in one of the fields, you must use a ? (question mark) in the other.

  • Snapshot schedules don't support the following frequencies:

    • Snapshots scheduled more frequently than 1 per hour.

    • Snapshots scheduled less frequently than 1 per day (24 hours).

    If you have overlapping schedules that result in scheduling snapshots within a 1 hour window, a validation error results.

The following table has some sample cron strings.

Minutes Hours Day of week Meaning

0

14-20/1

TUE

Every hour between 2pm and 8pm on Tuesday.

0

21

MON-FRI

Every night at 9pm Monday–Friday.

30

0/6

SAT-SUN

Every 6 hour increment on Saturday and Sunday starting at 30 minutes after midnight (00:30) that day. This results in a snapshot at [00:30, 06:30, 12:30, and 18:30] each day.

30

12/4

*

Every 4 hour increment starting at 12:30 each day. This resolves to [12:30, 16:30, 20:30].

The following example demonstrates how to create a schedule that runs in 2-hour increments starting at 15:15 each day.

 cron(15 15/2 *)

You can use the Amazon Redshift Serverless console, API, or Amazon CLI to create a snapshot schedule.

To schedule a snapshot

  1. On the Amazon Redshift Serverless console, choose Data backup.

  2. Choose Snapshot schedules.

  3. Choose Create schedule.

  4. Enter a name for the snapshot schedule.

  5. Select the namespace to create snapshots for.

  6. Enter a cron expression for the schedule or use the schedule builder to create one.

  7. (Optional) Choose a retention period. If you choose Custom value, specify the number of days.

  8. Choose Create schedule.