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 enter1/10
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
orDay-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 theDay-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
andDay-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
-
On the Amazon Redshift Serverless console, choose Data backup.
-
Choose Snapshot schedules.
-
Choose Create schedule.
-
Enter a name for the snapshot schedule.
-
Select the namespace to create snapshots for.
-
Enter a cron expression for the schedule or use the schedule builder to create one.
-
(Optional) Choose a retention period. If you choose Custom value, specify the number of days.
-
Choose Create schedule.