# Perform time travel and version travel queries
<a name="querying-iceberg-time-travel-and-version-travel-queries"></a>

Each Apache Iceberg table maintains a versioned manifest of the Amazon S3 objects that it contains. Previous versions of the manifest can be used for time travel and version travel queries.

Time travel queries in Athena query Amazon S3 for historical data from a consistent snapshot as of a specified date and time. Version travel queries in Athena query Amazon S3 for historical data as of a specified snapshot ID.

## Time travel queries
<a name="querying-iceberg-time-travel-queries"></a>

To run a time travel query, use `FOR TIMESTAMP AS OF timestamp` after the table name in the `SELECT` statement, as in the following example.

```
SELECT * FROM iceberg_table FOR TIMESTAMP AS OF timestamp
```

The system time to be specified for traveling is either a timestamp or timestamp with a time zone. If not specified, Athena considers the value to be a timestamp in UTC time.

The following example time travel queries select CloudTrail data for the specified date and time.

```
SELECT * FROM iceberg_table FOR TIMESTAMP AS OF TIMESTAMP '2020-01-01 10:00:00 UTC'
```

```
SELECT * FROM iceberg_table FOR TIMESTAMP AS OF (current_timestamp - interval '1' day)
```

## Version travel queries
<a name="querying-iceberg-version-travel-queries"></a>

To execute a version travel query (that is, view a consistent snapshot as of a specified version), use `FOR VERSION AS OF version` after the table name in the `SELECT` statement, as in the following example.

```
SELECT * FROM [db_name.]table_name FOR VERSION AS OF version         
```

The *version* parameter is the `bigint` snapshot ID associated with an Iceberg table version.

The following example version travel query selects data for the specified version.

```
SELECT * FROM iceberg_table FOR VERSION AS OF 949530903748831860
```

**Note**  
The `FOR SYSTEM_TIME AS OF` and `FOR SYSTEM_VERSION AS OF` clauses in Athena engine version 2 have been replaced by the `FOR TIMESTAMP AS OF` and `FOR VERSION AS OF` clauses in Athena engine version 3.

### Retrieve the snapshot ID
<a name="querying-iceberg-table-snapshot-id"></a>

You can use the Java [SnapshotUtil](https://iceberg.apache.org/javadoc/1.6.0/org/apache/iceberg/util/SnapshotUtil.html) class provided by Iceberg to retrieve the Iceberg snapshot ID, as in the following example.

```
import org.apache.iceberg.Table;
import org.apache.iceberg.aws.glue.GlueCatalog;
import org.apache.iceberg.catalog.TableIdentifier;
import org.apache.iceberg.util.SnapshotUtil;

import java.text.SimpleDateFormat;
import java.util.Date;

Catalog catalog = new GlueCatalog();

Map<String, String> properties = new HashMap<String, String>();
properties.put("warehouse", "s3://amzn-s3-demo-bucket/my-folder");
catalog.initialize("my_catalog", properties);

Date date = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").parse("2022/01/01 00:00:00");
long millis = date.getTime();

TableIdentifier name = TableIdentifier.of("db", "table");
Table table = catalog.loadTable(name);
long oldestSnapshotIdAfter2022 = SnapshotUtil.oldestAncestorAfter(table, millis);
```

## Combine time and version travel
<a name="querying-iceberg-combining-time-and-version-travel"></a>

You can use time travel and version travel syntax in the same query to specify different timing and versioning conditions, as in the following example.

```
SELECT table1.*, table2.* FROM 
  [db_name.]table_name FOR TIMESTAMP AS OF (current_timestamp - interval '1' day) AS table1 
  FULL JOIN 
  [db_name.]table_name FOR VERSION AS OF 5487432386996890161 AS table2 
  ON table1.ts = table2.ts 
  WHERE (table1.id IS NULL OR table2.id IS NULL)
```