# Generating column statistics on a schedule
Follow these steps to configure a schedule for generating column statistics in the AWS Glue Data Catalog using the AWS Glue console, the AWS CLI, or the [CreateColumnStatisticsTaskSettings](https://docs.aws.amazon.com/glue/latest/dg/aws-glue-api-crawler-column-statistics.html#aws-glue-api-crawler-column-statistics-CreateColumnStatisticsTaskSettings) operation.
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#### [ Console ]
**To generate column statistics using the console**
1. Sign in to the AWS Glue console at [https://console.aws.amazon.com/glue/](https://console.aws.amazon.com/glue/).
1. Choose Data Catalog tables.
1. Choose a table from the list.
1. Choose **Column statistics** tab in the lower section of the **Tables** page.
1. You can also choose **Generate on schedule** under **Column statistics** from **Actions**.
1. On the **Generate statistics on schedule** page, configure a recurring schedule for running the column statistics task by choosing the frequency and start time. You can choose the frequency to be hourly, daily, weekly, or define a cron expression to specify the schedule.
A cron expression is a string representing a schedule pattern, consisting of 6 fields separated by spaces: \$1 \$1 \$1 \$1 \$1 For example, to run a task every day at midnight, the cron expression would be: 0 0 \$1 \$1 ? \$1
For more information, see [Cron expressions](https://docs.aws.amazon.com/glue/latest/dg/monitor-data-warehouse-schedule.html#CronExpressions).
![\[The screenshot shows the options available to generate column stats.\]](http://docs.aws.amazon.com/glue/latest/dg/images/generate-column-stats-schedule.png)
1. Next, choose the column option to generate statistics.
+ **All columns** – Choose this option to generate statistics for all columns in the table.
+ **Selected columns** – Choose this option to generate statistics for specific columns. You can select the columns from the drop-down list.
1. Choose an IAM role or create an existing role that has permissions to generate statistics. AWS Glue assumes this role to generate column statistics.
A quicker approach is to let the AWS Glue console to create a role for you. The role that it creates is specifically for generating column statistics, and includes the `AWSGlueServiceRole` AWS managed policy plus the required inline policy for the specified data source.
If you specify an existing role for generating column statistics, ensure that it includes the `AWSGlueServiceRole` policy or equivalent (or a scoped down version of this policy), plus the required inline policies.
1. (Optional) Next, choose a security configuration to enable at-rest encryption for logs.
1. (Optional) You can choose a sample size by indicating only a specific percent of rows from the table to generate statistics. The default is all rows. Use the up and down arrows to increase or decrease the percent value.
We recommend to include all rows in the table to compute accurate statistics. Use sample rows to generate column statistics only when approximate values are acceptable.
1. Choose **Generate statistics** to run the column statistics generation task.
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#### [ AWS CLI ]
You can use the following AWS CLI example to create a column statistics generation schedule. The database-name, table-name, and role are required parameters, and optional parameters are schedule, column-name-list, catalog-id, sample-size, and security-configuration.
```
aws glue create-column-statistics-task-settings \
--database-name 'database_name' \
--table-name table_name \
--role 'arn:aws:iam::123456789012:role/stats-role' \
--schedule 'cron(0 0-5 14 * * ?)' \
--column-name-list 'col-1' \
--catalog-id '123456789012' \
--sample-size '10.0 ' \
--security-configuration 'test-security'
```
You can generate column statistics also by calling the [StartColumnStatisticsTaskRun](https://docs.aws.amazon.com/glue/latest/dg/aws-glue-api-crawler-column-statistics.html#aws-glue-api-crawler-column-statistics-StartColumnStatisticsTaskRun) operation.
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# Managing the schedule for column statistics generation
You can manage the scheduling operations such as updating, starting, stopping, and deleting schedules for the column statistics generation in AWS Glue. You can use AWS Glue console, AWS CLI, or [AWS Glue column statistics API operations](https://docs.aws.amazon.com/glue/latest/dg/aws-glue-api-crawler-column-statistics.html) to perform these tasks.
**Topics**
+ [Updating the column statistics generation schedule](#update-column-stats-shedule)
+ [Stopping the schedule for column statistics generation](#stop-column-stats-schedule)
+ [Resuming the schedule for column statistics generation](#resume-column-stats-schedule)
+ [Deleting column statistics generation schedule](#delete-column-stats-schedule)
## Updating the column statistics generation schedule
You can update the schedule to trigger the column statistics generation task after it has been created. You can use the AWS Glue console, AWS CLI, or run the [UpdateColumnStatisticsTaskSettings](https://docs.aws.amazon.com/glue/latest/dg/aws-glue-api-crawler-column-statistics.html#aws-glue-api-crawler-column-statistics-UpdateColumnStatisticsTaskSettings) operation to update the schedule for a table. You can modify the parameters of an existing schedule, such as the schedule type (on-demand, or scheduled) and other optional parameters.
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#### [ AWS Management Console ]
**To update the settings for a column statistics generation task**
1. Sign in to the AWS Glue console at [https://console.aws.amazon.com/glue/](https://console.aws.amazon.com/glue/).
1. Choose the table that you want to update from the tables list.
1. In the lower section of the table details page, choose **Column statistics**.
1. Under **Actions**, choose **Edit** to update the schedule.
1. Make the desired changes to the schedule, and choose **Save**.
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#### [ AWS CLI ]
If you are not using AWS Glue's statistics generation feature in the console, you can manually update the schedule using the `update-column-statistics-task-settings` command. The following example shows how to update column statistics using AWS CLI.
```
aws glue update-column-statistics-task-settings \
--database-name 'database_name' \
--table-name 'table_name' \
--role arn:aws:iam::123456789012:role/stats_role \
--schedule 'cron(0 0-5 16 * * ?)' \
--column-name-list 'col-1' \
--sample-size '20.0' \
--catalog-id '123456789012'\
--security-configuration 'test-security'
```
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## Stopping the schedule for column statistics generation
If you no longer need the incremental statistics, you can stop the scheduled generation to save resources and costs. Pausing the schedule doesn't impact the previously generated statistics. You can resume the schedule at your convenience.
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#### [ AWS Management Console ]
**To stop the schedule for a column statistics generation task**
1. On AWS Glue console, choose **Tables** under Data Catalog.
1. Select a table with column statistics.
1. On the **Table details** page, choose **Column statistics**.
1. Under **Actions**, choose **Scheduled generation**, **Pause**.
1. Choose **Pause** to confirm.
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#### [ AWS CLI ]
To stop a column statistics task run schedule using the AWS CLI, you can use the following command:
```
aws glue stop-column-statistics-task-run-schedule \
--database-name ''database_name' \
--table-name 'table_name'
```
Replace the `database_name` and the `table_name` with the actual names of the database and table for which you want to stop the column statistics task run schedule.
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## Resuming the schedule for column statistics generation
If you've paused the statistics generation schedule, AWS Glue allows you to resume the schedule at your convenience. You can resume the schedule using the AWS Glue console, AWS CLI, or the [StartColumnStatisticsTaskRunSchedule](https://docs.aws.amazon.com/glue/latest/dg/aws-glue-api-crawler-column-statistics.html#aws-glue-api-crawler-column-statistics-StartColumnStatisticsTaskRunSchedule) operation.
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#### [ AWS Management Console ]
**To resume the schedule for column statistics generation**
1. On AWS Glue console, choose **Tables** under Data Catalog.
1. Select a table with column statistics.
1. On the **Table details** page, choose **Column statistics**.
1. Under **Actions**, choose **Scheduled generation**, and choose **Resume**.
1. Choose **Resume**to confirm.
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#### [ AWS CLI ]
Replace the `database_name` and the `table_name` with the actual names of the database and table for which you want to stop the column statistics task run schedule.
```
aws glue start-column-statistics-task-run-schedule \
--database-name 'database_name' \
--table-name 'table_name'
```
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## Deleting column statistics generation schedule
While maintaining up-to-date statistics is generally recommended for optimal query performance, there are specific use cases where removing the automatic generation schedule might be beneficial.
+ If the data remains relatively static, the existing column statistics may remain accurate for an extended period, reducing the need for frequent updates. Deleting the schedule can prevent unnecessary resource consumption and overhead associated with regenerating statistics on unchanging data.
+ When manual control over statistics generation is preferred. By deleting the automatic schedule, administrators can selectively update column statistics at specific intervals or after significant data changes, aligning the process with their maintenance strategies and resource allocation needs.
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#### [ AWS Management Console ]
**To delete the schedule for column statistics generation**
1. On AWS Glue console, choose **Tables** under Data Catalog.
1. Select a table with column statistics.
1. On the **Table details** page, choose **Column statistics**.
1. Under **Actions**, choose **Scheduled generation**, **Delete**.
1. Choose **Delete**to confirm.
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#### [ AWS CLI ]
Replace the `database_name` and the `table_name` with the actual names of the database and table for which you want to stop the column statistics task run schedule.
You can delete column statistics schedule using the [DeleteColumnStatisticsTaskSettings](https://docs.aws.amazon.com/glue/latest/dg/aws-glue-api-crawler-column-statistics.html#aws-glue-api-crawler-column-statistics-DeleteColumnStatisticsTaskSettings) API operation or AWS CLI. The following example shows how to delete the schedule for generating column statistics using AWS Command Line Interface (AWS CLI).
```
aws glue delete-column-statistics-task-settings \
--database-name 'database_name' \
--table-name 'table_name'
```
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