# ago

Return time as epoch millis before the given period (in ISO-8601 duration format).

Examples:

* "PT20.345S" -- parses as "20.345 seconds"
* "PT15M" -- parses as "15 minutes" (where a minute is 60 seconds)
* "PT10H" -- parses as "10 hours" (where an hour is 3600 seconds)
* "P2D" -- parses as "2 days" (where a day is 24 hours or 86400 seconds)
* "P2DT3H4M" -- parses as "2 days, 3 hours and 4 minutes"
* "P-6H3M" -- parses as "-6 hours and +3 minutes"
* "-P6H3M" -- parses as "-6 hours and -3 minutes"
* "-P-6H+3M" -- parses as "+6 hours and -3 minutes"

## Signature

> ago()

## Usage Examples

```sql
select ago("P1D") AS oneDayAgo
FROM ignoreMe
```

| oneDayAgo     |
| ------------- |
| 1639150454255 |

This function is typically used in predicate to filter on timestamp for recent data. e.g. filter data on recent 1 day.

```sql
SELECT * 
FROM tableName
WHERE tsInMillis > ago("P1D")
```


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