Iceberg Connector¶

Overview¶

The Iceberg connector allows querying data stored in Iceberg tables.

Metastores¶

Iceberg tables store most of the metadata in the metadata files, along with the data on the filesystem, but it still requires a central place to find the current location of the current metadata pointer for a table. This central place is called the Iceberg Catalog. The Presto Iceberg connector supports different types of Iceberg Catalogs : HIVE, NESSIE, REST, and HADOOP.

To configure the Iceberg connector, create a catalog properties file etc/catalog/iceberg.properties. To define the catalog type, iceberg.catalog.type property is required along with the following contents, with the property values replaced as follows:

Hive Metastore catalog¶

The Iceberg connector supports the same configuration for HMS as a Hive connector.

connector.name=iceberg
hive.metastore.uri=hostname:port
iceberg.catalog.type=hive

Glue catalog¶

The Iceberg connector supports the same configuration for Glue as a Hive connector.

connector.name=iceberg
hive.metastore=glue
iceberg.catalog.type=hive

There are additional configurations available when using the Iceberg connector configured with Hive or Glue catalogs.

Nessie catalog¶

To use a Nessie catalog, configure the catalog type as iceberg.catalog.type=nessie.

connector.name=iceberg
iceberg.catalog.type=nessie
iceberg.catalog.warehouse=/tmp
iceberg.nessie.uri=https://localhost:19120/api/v1

Additional supported properties for the Nessie catalog:

Setting Up Nessie With Docker¶

To set up a Nessie instance locally using the Docker image, see Setting up Nessie. Once the Docker instance is up and running, you should see logs similar to the following example:

2023-09-05 13:11:37,905 INFO  [io.quarkus] (main) nessie-quarkus 0.69.0 on JVM (powered by Quarkus 3.2.4.Final) started in 1.921s. Listening on: http://0.0.0.0:19120
2023-09-05 13:11:37,906 INFO  [io.quarkus] (main) Profile prod activated.
2023-09-05 13:11:37,906 INFO  [io.quarkus] (main) Installed features: [agroal, amazon-dynamodb, cassandra-client, cdi, google-cloud-bigtable, hibernate-validator, jdbc-postgresql, logging-sentry, micrometer, mongodb-client, narayana-jta, oidc, opentelemetry, reactive-routes, resteasy, resteasy-jackson, security, security-properties-file, smallrye-context-propagation, smallrye-health, smallrye-openapi, swagger-ui, vertx]

If log messages related to Nessie’s OpenTelemetry collector appear similar to the following example, you can disable OpenTelemetry using the configuration option quarkus.otel.sdk.disabled=true.

2023-08-27 11:10:02,492 INFO  [io.qua.htt.access-log] (executor-thread-1) 172.17.0.1 - - [27/Aug/2023:11:10:02 +0000] "GET /api/v1/config HTTP/1.1" 200 62
2023-08-27 11:10:05,007 SEVERE [io.ope.exp.int.grp.OkHttpGrpcExporter] (OkHttp http://localhost:4317/...) Failed to export spans. The request could not be executed. Full error message: Failed to connect to localhost/127.0.0.1:4317

For example, start the Docker image using the following command: docker run -p 19120:19120 -e QUARKUS_OTEL_SDK_DISABLED=true ghcr.io/projectnessie/nessie

For more information about this configuration option and other related options, see the OpenTelemetry Configuration Reference.

For more information about troubleshooting OpenTelemetry traces, see Troubleshooting traces.

If an error similar to the following example is displayed, this is probably because you are interacting with an http server, and not an https server. You need to set iceberg.nessie.uri to http://localhost:19120/api/v1.

Caused by: javax.net.ssl.SSLException: Unsupported or unrecognized SSL message
    at sun.security.ssl.SSLSocketInputRecord.handleUnknownRecord(SSLSocketInputRecord.java:448)
    at sun.security.ssl.SSLSocketInputRecord.decode(SSLSocketInputRecord.java:174)
    at sun.security.ssl.SSLTransport.decode(SSLTransport.java:111)
    at sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1320)
    at sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1233)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:417)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:389)
    at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:558)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:201)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:167)
    at org.projectnessie.client.http.impl.jdk8.UrlConnectionRequest.executeRequest(UrlConnectionRequest.java:71)
    ... 42 more

REST catalog¶

To use a REST catalog, configure the catalog type as iceberg.catalog.type=rest. A minimal configuration includes:

connector.name=iceberg
iceberg.catalog.type=rest
iceberg.rest.uri=https://localhost:8181

Additional supported properties for the REST catalog:

Hadoop catalog¶

To use a Hadoop catalog, configure the catalog type as iceberg.catalog.type=hadoop. A minimal configuration includes:

connector.name=iceberg
iceberg.catalog.type=hadoop
iceberg.catalog.warehouse=hdfs://hostname:port

Hadoop catalog configuration properties:

Configuration Properties¶

The following configuration properties are available for all catalog types:

Table Properties¶

Table properties set metadata for the underlying tables. This is key for CREATE TABLE/CREATE TABLE AS statements. Table properties are passed to the connector using a WITH clause:

CREATE TABLE tablename
WITH (
    property_name = property_value,
    ...
)

The following table properties are available, which are specific to the Presto Iceberg connector:

The table definition below specifies format ORC, partitioning by columns c1 and c2, and a file system location of s3://test_bucket/test_schema/test_table:

CREATE TABLE test_table (
    c1 bigint,
    c2 varchar,
    c3 double
)
WITH (
    format = 'ORC',
    partitioning = ARRAY['c1', 'c2'],
    location = 's3://test_bucket/test_schema/test_table')
)

Session Properties¶

Session properties set behavior changes for queries executed within the given session.

Caching Support¶

Manifest File Caching¶

As of Iceberg version 1.1.0, Apache Iceberg provides a mechanism to cache the contents of Iceberg manifest files in memory. This feature helps to reduce repeated reads of small Iceberg manifest files from remote storage.

The following configuration properties are available:

Alluxio Data Cache¶

A Presto worker caches remote storage data in its original form (compressed and possibly encrypted) on local SSD upon read.

The following configuration properties are required to set in the Iceberg catalog file (catalog/iceberg.properties):

cache.enabled=true
cache.base-directory=file:///mnt/flash/data
cache.type=ALLUXIO
cache.alluxio.max-cache-size=1600GB
hive.node-selection-strategy=SOFT_AFFINITY

JMX queries to get the metrics and verify the cache usage:

SELECT * FROM jmx.current."com.facebook.alluxio:name=client.cachehitrate,type=gauges";

SELECT * FROM jmx.current."com.facebook.alluxio:name=client.cachebytesreadcache,type=meters";

SHOW TABLES FROM jmx.current like '%alluxio%';

File And Stripe Footer Cache¶

Caches open file descriptors and stripe or file footer information in leaf worker memory. These pieces of data are mostly frequently accessed when reading files.

The following configuration properties are required to set in the Iceberg catalog file (catalog/iceberg.properties):

# scheduling
hive.node-selection-strategy=SOFT_AFFINITY

# orc
iceberg.orc.file-tail-cache-enabled=true
iceberg.orc.file-tail-cache-size=100MB
iceberg.orc.file-tail-cache-ttl-since-last-access=6h
iceberg.orc.stripe-metadata-cache-enabled=true
iceberg.orc.stripe-footer-cache-size=100MB
iceberg.orc.stripe-footer-cache-ttl-since-last-access=6h
iceberg.orc.stripe-stream-cache-size=300MB
iceberg.orc.stripe-stream-cache-ttl-since-last-access=6h

# parquet
iceberg.parquet.metadata-cache-enabled=true
iceberg.parquet.metadata-cache-size=100MB
iceberg.parquet.metadata-cache-ttl-since-last-access=6h

JMX queries to get the metrics and verify the cache usage:

SELECT * FROM jmx.current."com.facebook.presto.hive:name=iceberg_parquetmetadata,type=cachestatsmbean";

Metastore Cache¶

Metastore Cache only caches the schema, table, and table statistics. The table object cached in the tableCache is only used for reading the table metadata location and table properties and, the rest of the table metadata is fetched from the filesystem/object storage metadata location.

hive.metastore-cache-ttl=2d
hive.metastore-refresh-interval=3d
hive.metastore-cache-maximum-size=10000000

Extra Hidden Metadata Columns¶

The Iceberg connector exposes extra hidden metadata columns. You can query these as part of a SQL query by including them in your SELECT statement.

$path column¶

• $path: Full file system path name of the file for this row

SELECT "$path", regionkey FROM "ctas_nation";

        $path                    |  regionkey
---------------------------------+-----------
 /full/path/to/file/file.parquet | 2

$data_sequence_number column¶

• $data_sequence_number: The Iceberg data sequence number in which this row was added

SELECT "$data_sequence_number", regionkey FROM "ctas_nation";

        $data_sequence_number     |  regionkey
----------------------------------+------------
             2                    | 3

Extra Hidden Metadata Tables¶

The Iceberg connector exposes extra hidden metadata tables. You can query these as a part of a SQL query by appending name to the table.

$properties Table¶

• $properties : General properties of the given table

SELECT * FROM "ctas_nation$properties";

        key           |  value
----------------------+---------
 write.format.default | PARQUET

$history Table¶

• $history : History of table state changes

SELECT * FROM "ctas_nation$history";

           made_current_at            |     snapshot_id     | parent_id | is_current_ancestor
--------------------------------------+---------------------+-----------+---------------------
2022-11-25 20:56:31.784 Asia/Kolkata  | 7606232158543069775 | NULL      | true

$snapshots Table¶

• $snapshots : Details about the table snapshots. For more information see Snapshots in the Iceberg Table Spec.

SELECT * FROM "ctas_nation$snapshots";

             committed_at             |     snapshot_id     | parent_id | operation |                                                  manifest_list                                           |                                                                                 summary
--------------------------------------+---------------------+-----------+-----------+----------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2022-11-25 20:56:31.784 Asia/Kolkata  | 7606232158543069775 | NULL      | append    | s3://my-bucket/ctas_nation/metadata/snap-7606232158543069775-1-395a2cad-b244-409b-b030-cc44949e5a4e.avro | {changed-partition-count=1, added-data-files=1, total-equality-deletes=0, added-records=25, total-position-deletes=0, added-files-size=1648, total-delete-files=0, total-files-size=1648, total-records=25, total-data-files=1}

$manifests Table¶

• $manifests : Details about the manifests of different table snapshots. For more information see Manifests in the Iceberg Table Spec.

SELECT * FROM "ctas_nation$manifests";

                                           path                                  | length | partition_spec_id |  added_snapshot_id  | added_data_files_count | existing_data_files_count | deleted_data_files_count | partitions
---------------------------------------------------------------------------------+--------+-------------------+---------------------+------------------------+---------------------------+--------------------------+-----------
s3://my-bucket/ctas_nation/metadata/395a2cad-b244-409b-b030-cc44949e5a4e-m0.avro |   5957 |                 0 | 7606232158543069775 |                      1 |                         0 |                    0     |    []

$partitions Table¶

• $partitions : Detailed partition information for the table

SELECT * FROM "ctas_nation$partitions";

 row_count | file_count | total_size |           nationkey           |                   name                   |          regionkey           |                          comment
-----------+------------+------------+-------------------------------+------------------------------------------+------------------------------+------------------------------------------------------------
    25     |          1 |       1648 | {min=0, max=24, null_count=0} | {min=ALGERIA, max=VIETNAM, null_count=0} | {min=0, max=4, null_count=0} | {min= haggle. careful, max=y final packaget, null_count=0}

$files Table¶

• $files : Overview of data files in the current snapshot of the table

SELECT * FROM "ctas_nation$files";

 content |                                      file_path                               | file_format | record_count | file_size_in_bytes |        column_sizes         |       value_counts       |  null_value_counts   | nan_value_counts |          lower_bounds                     |             upper_bounds                   | key_metadata | split_offsets | equality_ids
---------+------------------------------------------------------------------------------+-------------+--------------+--------------------+-----------------------------+--------------------------+----------------------+------------------+-------------------------------------------+--------------------------------------------+--------------+---------------+-------------
   0     | s3://my-bucket/ctas_nation/data/9f889274-6f74-4d28-8164-275eef99f660.parquet | PARQUET     |           25 |               1648 | {1=52, 2=222, 3=105, 4=757} | {1=25, 2=25, 3=25, 4=25} | {1=0, 2=0, 3=0, 4=0} |  NULL            | {1=0, 2=ALGERIA, 3=0, 4= haggle. careful} | {1=24, 2=VIETNAM, 3=4, 4=y final packaget} | NULL         | NULL          | NULL

$changelog Table¶

This table lets you view which row-level changes have occurred to the table in a particular order over time. The $changelog table represents the history of changes to the table, while also making the data available to process through a query.

The result of a changelog query always returns a static schema with four columns:

1. operation: (VARCHAR) indicating whether the row was inserted, updated, or deleted.

2. ordinal: (int) A number indicating a relative order that a particular change needs to be applied to the table relative to all other changes.

3. snapshotid: (bigint) Represents the snapshot a row-level change was made in.

4. rowdata: (row(T)) which includes the data for the particular row. The inner values of this type match the schema of the parent table.

The changelog table can be queried with the following name format:

... FROM "<table>[@<begin snapshot ID>]$changelog[@<end snapshot ID>]"

• <table> is the name of the table.

• <begin snapshot ID> is the snapshot of the table you want to begin viewing changes from. This parameter is optional. If absent, the oldest available snapshot is used.

• <end snapshot ID> is the last snapshot for which you want to view changes. This parameter is optional. If absent, the most current snapshot of the table is used.

One use for the $changelog table would be to find when a record was inserted or removed from the table. To accomplish this, the $changelog table can be used in conjunction with the $snapshots table. First, choose a snapshot ID from the $snapshots table to choose the starting point.

SELECT * FROM "orders$snapshots";

                committed_at                 |     snapshot_id     |      parent_id      | operation |                                                                                       manifest_list                                                                                        |                                                                                                              summary
---------------------------------------------+---------------------+---------------------+-----------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 2023-09-26 08:45:20.930 America/Los_Angeles | 2423571386296047175 | NULL                | append    | file:/var/folders/g_/6_hxl7r16qdddw7956j_r88h0000gn/T/PrestoTest8140889264166671718/catalog/tpch/ctas_orders/metadata/snap-2423571386296047175-1-3f288b1c-95a9-406b-9e17-9cfe31a11b48.avro | {changed-partition-count=1, added-data-files=4, total-equality-deletes=0, added-records=100, total-position-deletes=0, added-files-size=9580, total-delete-files=0, total-files-size=9580, total-records=100, total-data-files=4}
 2023-09-26 08:45:36.942 America/Los_Angeles | 8702997868627997320 | 2423571386296047175 | append    | file:/var/folders/g_/6_hxl7r16qdddw7956j_r88h0000gn/T/PrestoTest8140889264166671718/catalog/tpch/ctas_orders/metadata/snap-8702997868627997320-1-a2e1c714-7eed-4e2c-b144-dae4147ebaa4.avro | {changed-partition-count=1, added-data-files=1, total-equality-deletes=0, added-records=1, total-position-deletes=0, added-files-size=1687, total-delete-files=0, total-files-size=11267, total-records=101, total-data-files=5}
 2023-09-26 08:45:39.866 America/Los_Angeles | 7615903782581283889 | 8702997868627997320 | append    | file:/var/folders/g_/6_hxl7r16qdddw7956j_r88h0000gn/T/PrestoTest8140889264166671718/catalog/tpch/ctas_orders/metadata/snap-7615903782581283889-1-d94c2114-fd22-4de2-9ab5-c0b5bf67282f.avro | {changed-partition-count=1, added-data-files=3, total-equality-deletes=0, added-records=3, total-position-deletes=0, added-files-size=4845, total-delete-files=0, total-files-size=16112, total-records=104, total-data-files=8}
 2023-09-26 08:45:48.404 America/Los_Angeles |  677209275408372885 | 7615903782581283889 | append    | file:/var/folders/g_/6_hxl7r16qdddw7956j_r88h0000gn/T/PrestoTest8140889264166671718/catalog/tpch/ctas_orders/metadata/snap-677209275408372885-1-ad69e208-1440-459b-93e8-48e61f961758.avro  | {changed-partition-count=1, added-data-files=3, total-equality-deletes=0, added-records=5, total-position-deletes=0, added-files-size=4669, total-delete-files=0, total-files-size=20781, total-records=109, total-data-files=11}

Now that we know the snapshots available to query in the changelog, we can see what changes were made to the table since it was created. Specifically, this example uses the earliest snapshot ID: 2423571386296047175

SELECT * FROM "ctas_orders@2423571386296047175$changelog" ORDER BY ordinal;

 operation | ordinal |     snapshotid      |                                                                                                                   rowdata
-----------+---------+---------------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 INSERT    |       0 | 8702997868627997320 | {orderkey=37504, custkey=1291, orderstatus=O, totalprice=165509.83, orderdate=1996-03-04, orderpriority=5-LOW, clerk=Clerk#000000871, shippriority=0, comment=c theodolites alongside of the fluffily bold requests haggle quickly against }
 INSERT    |       1 | 7615903782581283889 | {orderkey=12001, custkey=739, orderstatus=F, totalprice=138635.75, orderdate=1994-07-07, orderpriority=2-HIGH, clerk=Clerk#000000863, shippriority=0, comment=old, even theodolites. regular, special theodolites use furio}
 INSERT    |       1 | 7615903782581283889 | {orderkey=17989, custkey=364, orderstatus=F, totalprice=133669.05, orderdate=1994-01-17, orderpriority=4-NOT SPECIFIED, clerk=Clerk#000000547, shippriority=0, comment=ously express excuses. even theodolit}
 INSERT    |       1 | 7615903782581283889 | {orderkey=37504, custkey=1291, orderstatus=O, totalprice=165509.83, orderdate=1996-03-04, orderpriority=5-LOW, clerk=Clerk#000000871, shippriority=0, comment=c theodolites alongside of the fluffily bold requests haggle quickly against }
 INSERT    |       2 |  677209275408372885 | {orderkey=17991, custkey=92, orderstatus=O, totalprice=20732.51, orderdate=1998-07-09, orderpriority=4-NOT SPECIFIED, clerk=Clerk#000000636, shippriority=0, comment= the quickly express accounts. iron}
 INSERT    |       2 |  677209275408372885 | {orderkey=17989, custkey=364, orderstatus=F, totalprice=133669.05, orderdate=1994-01-17, orderpriority=4-NOT SPECIFIED, clerk=Clerk#000000547, shippriority=0, comment=ously express excuses. even theodolit}
 INSERT    |       2 |  677209275408372885 | {orderkey=17990, custkey=458, orderstatus=O, totalprice=218031.58, orderdate=1998-03-18, orderpriority=3-MEDIUM, clerk=Clerk#000000340, shippriority=0, comment=ounts wake final foxe}
 INSERT    |       2 |  677209275408372885 | {orderkey=18016, custkey=403, orderstatus=O, totalprice=174070.99, orderdate=1996-03-19, orderpriority=1-URGENT, clerk=Clerk#000000629, shippriority=0, comment=ly. quickly ironic excuses are furiously. carefully ironic pack}
 INSERT    |       2 |  677209275408372885 | {orderkey=18017, custkey=958, orderstatus=F, totalprice=203091.02, orderdate=1993-03-26, orderpriority=1-URGENT, clerk=Clerk#000000830, shippriority=0, comment=sleep quickly bold requests. slyly pending pinto beans haggle in pla}

$refs Table¶

• $refs : Details about Iceberg references including branches and tags. For more information see Branching and Tagging.

SELECT * FROM "ctas_nation$refs";

   name     |  type  |     snapshot_id     | max_reference_age_in_ms | min_snapshots_to_keep | max_snapshot_age_in_ms
------------+--------+---------------------+-------------------------+-----------------------+------------------------
 main       | BRANCH | 3074797416068623476 | NULL                    | NULL                  | NULL
 testBranch | BRANCH | 3374797416068698476 | NULL                    | NULL                  | NULL
 testTag    | TAG    | 4686954189838128572 | 10                      | NULL                  | NULL

Procedures¶

Use the CALL statement to perform data manipulation or administrative tasks. Procedures are available in the system schema of the catalog.

Register Table¶

Iceberg tables for which table data and metadata already exist in the file system can be registered with the catalog. Use the register_table procedure on the catalog’s system schema to register a table which already exists but does not known by the catalog.

The following arguments are available:

Examples:

• Register a table through supplying the target schema, desired table name, and the location of the table metadata:

  CALL iceberg.system.register_table('schema_name', 'table_name', 'hdfs://localhost:9000/path/to/iceberg/table/metadata/dir')
  
  CALL iceberg.system.register_table(table_name => 'table_name', schema => 'schema_name', metadata_location => 'hdfs://localhost:9000/path/to/iceberg/table/metadata/dir')
  

• Register a table through additionally supplying a specific metadata file:

  CALL iceberg.system.register_table('schema_name', 'table_name', 'hdfs://localhost:9000/path/to/iceberg/table/metadata/dir', '00000-35a08aed-f4b0-4010-95d2-9d73ef4be01c.metadata.json')
  
  CALL iceberg.system.register_table(table_name => 'table_name', schema => 'schema_name', metadata_location => 'hdfs://localhost:9000/path/to/iceberg/table/metadata/dir', metadata_file => '00000-35a08aed-f4b0-4010-95d2-9d73ef4be01c.metadata.json')
  

Unregister Table¶

Iceberg tables can be unregistered from the catalog using the unregister_table procedure on the catalog’s system schema.

The following arguments are available:

Examples:

CALL iceberg.system.unregister_table('schema_name', 'table_name')

CALL iceberg.system.unregister_table(table_name => 'table_name', schema => 'schema_name')

Rollback to Snapshot¶

Rollback a table to a specific snapshot ID. Iceberg can rollback to a specific snapshot ID by using the rollback_to_snapshot procedure on Iceberg’s system schema:

CALL iceberg.system.rollback_to_snapshot('schema_name', 'table_name', snapshot_id);

The following arguments are available:

Rollback to Timestamp¶

Rollback a table to a given point in time. Iceberg can rollback to a specific point in time by using the rollback_to_timestamp procedure on Iceberg’s system schema.

The following arguments are available:

Example:

CALL iceberg.system.rollback_to_timestamp('schema_name', 'table_name', TIMESTAMP '1995-04-26 00:00:00.000');

Set Current Snapshot¶

This procedure sets a current snapshot ID for a table by using snapshot_id or ref. Use either snapshot_id or ref, but do not use both in the same procedure.

The following arguments are available:

Examples:

• Set current table snapshot ID for the given table to 10000

  CALL iceberg.system.set_current_snapshot('schema_name', 'table_name', 10000);
  

• Set current table snapshot ID for the given table to snapshot ID of branch1

  CALL iceberg.system.set_current_snapshot(schema => 'schema_name', table_name => 'table_name', ref => 'branch1');
  

Expire Snapshots¶

Each DML (Data Manipulation Language) action in Iceberg produces a new snapshot while keeping the old data and metadata for snapshot isolation and time travel. Use expire_snapshots to remove older snapshots and their files.

This procedure removes old snapshots and their corresponding files, and never removes files which are required by a non-expired snapshot.

The following arguments are available:

Examples:

• Remove snapshots older than a specific day and time, but retain the last 10 snapshots:

  CALL iceberg.system.expire_snapshots('schema_name', 'table_name', TIMESTAMP '2023-08-31 00:00:00.000', 10);
  

• Remove snapshots with snapshot ID 10001 and 10002 (note that these snapshot IDs should not be the current snapshot):

  CALL iceberg.system.expire_snapshots(schema => 'schema_name', table_name => 'table_name', snapshot_ids => ARRAY[10001, 10002]);
  

Remove Orphan Files¶

Use to remove files which are not referenced in any metadata files of an Iceberg table.

The following arguments are available:

Examples:

• Remove any files which are not known to the table db.sample and older than specified timestamp:

  CALL iceberg.system.remove_orphan_files('db', 'sample', TIMESTAMP '2023-08-31 00:00:00.000');
  

• Remove any files which are not known to the table db.sample and created 3 days ago (by default):

  CALL iceberg.system.remove_orphan_files(schema => 'db', table_name => 'sample');
  

Fast Forward Branch¶

This procedure advances the current snapshot of the specified branch to a more recent snapshot from another branch without replaying any intermediate snapshots. branch can be fast-forwarded up to the to snapshot if branch is an ancestor of to.

The following arguments are available:

Examples:

• Fast-forward the dev branch to the latest snapshot of the main branch

  CALL iceberg.system.fast_forward('schema_name', 'table_name', 'dev', 'main');
  

• Given the branch named branch1 does not exist yet, create a new branch named branch1 and set it’s current snapshot equal to the latest snapshot of the main branch

  CALL iceberg.system.fast_forward('schema_name', 'table_name', 'branch1', 'main');
  

Set Table Property¶

Iceberg table property can be set from the catalog using the set_table_property procedure on the catalog’s system schema.

The following arguments are available:

Examples:

• Set table property commit.retry.num-retries to 10 for a Iceberg table

  CALL iceberg.system.set_table_property('schema_name', 'table_name', 'commit.retry.num-retries', '10');
  

SQL Support¶

The Iceberg connector supports querying and manipulating Iceberg tables and schemas (databases). Here are some examples of the SQL operations supported by Presto:

CREATE SCHEMA¶

Create a new Iceberg schema named web that stores tables in an S3 bucket named my-bucket:

CREATE SCHEMA iceberg.web
WITH (location = 's3://my-bucket/')

CREATE TABLE¶

Create a new Iceberg table named page_views in the web schema that is stored using the ORC file format, partitioned by ds and country:

CREATE TABLE iceberg.web.page_views (
  view_time timestamp,
  user_id bigint,
  page_url varchar,
  ds date,
  country varchar
)
WITH (
  format = 'ORC',
  partitioning = ARRAY['ds', 'country']
)

Create an Iceberg table with Iceberg format version 2:

CREATE TABLE iceberg.web.page_views_v2 (
  view_time timestamp,
  user_id bigint,
  page_url varchar,
  ds date,
  country varchar
)
WITH (
  format = 'ORC',
  partitioning = ARRAY['ds', 'country'],
  format_version = '2'
)

Partition Column Transform¶

Beyond selecting some particular columns for partitioning, you can use the transform functions and partition the table by the transformed value of the column.

Available transforms in the Presto Iceberg connector include:

• Bucket (partitions data into a specified number of buckets using a hash function)

• Truncate (partitions the table based on the truncated value of the field and can specify the width of the truncated value)

• Identity (partitions data using unmodified source value)

• Year (partitions data using integer value by extracting a date or timestamp year, as years from 1970)

• Month (partitions data using integer value by extracting a date or timestamp month, as months from 1970-01-01)

• Day (partitions data using integer value by extracting a date or timestamp day, as days from 1970-01-01)

• Hour (partitions data using integer value by extracting a timestamp hour, as hours from 1970-01-01 00:00:00)

Create an Iceberg table partitioned into 8 buckets of equal size ranges:

CREATE TABLE players (
    id int,
    name varchar,
    team varchar
)
WITH (
    format = 'ORC',
    partitioning = ARRAY['bucket(team, 8)']
);

Create an Iceberg table partitioned by the first letter of the team field:

CREATE TABLE players (
    id int,
    name varchar,
    team varchar
)
WITH (
    format = 'ORC',
    partitioning = ARRAY['truncate(team, 1)']
);

Create an Iceberg table partitioned by ds:

CREATE TABLE players (
    id int,
    name varchar,
    team varchar,
    ds date
)
WITH (
    format = 'ORC',
    partitioning = ARRAY['year(ds)']
);

Create an Iceberg table partitioned by ts:

CREATE TABLE players (
    id int,
    name varchar,
    team varchar,
    ts timestamp
)
WITH (
    format = 'ORC',
    partitioning = ARRAY['hour(ts)']
);

CREATE VIEW¶

The Iceberg connector supports creating views in Hive and Glue metastores. To create a view named view_page_views for the iceberg.web.page_views table created in the CREATE TABLE example:

CREATE VIEW iceberg.web.view_page_views AS SELECT user_id, country FROM iceberg.web.page_views;

INSERT INTO¶

Insert data into the page_views table:

INSERT INTO iceberg.web.page_views VALUES(TIMESTAMP '2023-08-12 03:04:05.321', 1, 'https://example.com', current_date, 'country');

CREATE TABLE AS SELECT¶

Create a new table page_views_new from an existing table page_views:

CREATE TABLE iceberg.web.page_views_new AS SELECT * FROM iceberg.web.page_views

SELECT¶

SELECT table operations are supported for Iceberg format version 1 and version 2 in the connector:

SELECT * FROM iceberg.web.page_views;

SELECT * FROM iceberg.web.page_views_v2;

Table with delete files¶

Iceberg V2 tables support row-level deletion. For more information see Row-level deletes in the Iceberg Table Spec. Presto supports reading delete files, including Position Delete Files and Equality Delete Files. When reading, Presto merges these delete files to read the latest results.

ALTER TABLE¶

Alter table operations are supported in the Iceberg connector:

ALTER TABLE iceberg.web.page_views ADD COLUMN zipcode VARCHAR;

ALTER TABLE iceberg.web.page_views RENAME COLUMN zipcode TO location;

ALTER TABLE iceberg.web.page_views DROP COLUMN location;

To add a new column as a partition column, identify the transform functions for the column. The table is partitioned by the transformed value of the column:

ALTER TABLE iceberg.web.page_views ADD COLUMN zipcode VARCHAR WITH (partitioning = 'identity');

ALTER TABLE iceberg.web.page_views ADD COLUMN location VARCHAR WITH (partitioning = 'truncate(2)');

ALTER TABLE iceberg.web.page_views ADD COLUMN location VARCHAR WITH (partitioning = 'bucket(8)');

ALTER TABLE iceberg.web.page_views ADD COLUMN dt date WITH (partitioning = 'year');

ALTER TABLE iceberg.web.page_views ADD COLUMN ts timestamp WITH (partitioning = 'month');

ALTER TABLE iceberg.web.page_views ADD COLUMN dt date WITH (partitioning = 'day');

ALTER TABLE iceberg.web.page_views ADD COLUMN ts timestamp WITH (partitioning = 'hour');

TRUNCATE¶

The Iceberg connector can delete all of the data from tables without dropping the table from the metadata catalog using TRUNCATE TABLE.

TRUNCATE TABLE nation;

TRUNCATE TABLE;

SELECT * FROM nation;

 nationkey | name | regionkey | comment
-----------+------+-----------+---------
(0 rows)

DELETE¶

The Iceberg connector can delete data from tables by using DELETE FROM. For example, to delete from the table lineitem:

DELETE FROM lineitem;

DELETE FROM lineitem WHERE linenumber = 1;

DELETE FROM lineitem WHERE linenumber not in (1, 3, 5, 7) and linestatus in ('O', 'F');

DROP TABLE¶

Drop the table page_views

DROP TABLE iceberg.web.page_views

• Dropping an Iceberg table with Hive Metastore and Glue catalogs only removes metadata from metastore.

• Dropping an Iceberg table with Hadoop and Nessie catalogs removes all the data and metadata in the table.

DROP VIEW¶

Drop the view view_page_views:

DROP VIEW iceberg.web.view_page_views;

DROP SCHEMA¶

Drop the schema iceberg.web:

DROP SCHEMA iceberg.web

SHOW CREATE TABLE¶

Show the SQL statement that creates the specified Iceberg table by using SHOW CREATE TABLE.

For example, SHOW CREATE TABLE from the partitioned Iceberg table customer:

SHOW CREATE TABLE customer;

CREATE TABLE iceberg.tpch_iceberg.customer (
    "custkey" bigint,
    "name" varchar,
    "address" varchar,
    "nationkey" bigint,
    "phone" varchar,
    "acctbal" double,
    "mktsegment" varchar,
    "comment" varchar
)
WITH (
    delete_mode = 'copy-on-write',
    format = 'PARQUET',
    format_version = '2',
    location = 's3a://tpch-iceberg/customer',
    partitioning = ARRAY['mktsegment']
)
(1 row)

SHOW CREATE TABLE from the un-partitioned Iceberg table region:

SHOW CREATE TABLE region;

CREATE TABLE iceberg.tpch_iceberg.region (
    "regionkey" bigint,
    "name" varchar,
    "comment" varchar
)
WITH (
    delete_mode = 'copy-on-write',
    format = 'PARQUET',
    format_version = '2',
    location = 's3a://tpch-iceberg/region'
)
(1 row)

SHOW COLUMNS¶

List the columns in table along with their data type and other attributes by using SHOW COLUMNS.

For example, SHOW COLUMNS from the partitioned Iceberg table customer:

SHOW COLUMNS FROM customer;

   Column   |  Type   |     Extra     | Comment
------------+---------+---------------+---------
 custkey    | bigint  |               |
 name       | varchar |               |
 address    | varchar |               |
 nationkey  | bigint  |               |
 phone      | varchar |               |
 acctbal    | double  |               |
 mktsegment | varchar | partition key |
 comment    | varchar |               |
 (8 rows)

SHOW COLUMNS from the un-partitioned Iceberg table region:

SHOW COLUMNS FROM region;

  Column   |  Type   | Extra | Comment
-----------+---------+-------+---------
 regionkey | bigint  |       |
 name      | varchar |       |
 comment   | varchar |       |
 (3 rows)

DESCRIBE¶

List the columns in table along with their data type and other attributes by using DESCRIBE. DESCRIBE is an alias for SHOW COLUMNS.

For example, DESCRIBE from the partitioned Iceberg table customer:

DESCRIBE customer;

   Column   |  Type   |     Extra     | Comment
------------+---------+---------------+---------
 custkey    | bigint  |               |
 name       | varchar |               |
 address    | varchar |               |
 nationkey  | bigint  |               |
 phone      | varchar |               |
 acctbal    | double  |               |
 mktsegment | varchar | partition key |
 comment    | varchar |               |
 (8 rows)

DESCRIBE from the un-partitioned Iceberg table region:

DESCRIBE region;

  Column   |  Type   | Extra | Comment
-----------+---------+-------+---------
 regionkey | bigint  |       |
 name      | varchar |       |
 comment   | varchar |       |
 (3 rows)

Schema Evolution¶

Iceberg and Presto Iceberg connector support in-place table evolution, also known as schema evolution, such as adding, dropping, and renaming columns. With schema evolution, users can evolve a table schema with SQL after enabling the Presto Iceberg connector.

Parquet Writer Version¶

Presto now supports Parquet writer versions V1 and V2 for the Iceberg catalog. It can be toggled using the session property parquet_writer_version and the config property hive.parquet.writer.version. Valid values for these properties are PARQUET_1_0 and PARQUET_2_0. Default is PARQUET_1_0.

Example Queries¶

Let’s create an Iceberg table named ctas_nation, created from the TPCH nation table. The table has four columns: nationkey, name, regionkey, and comment.

USE iceberg.tpch;
CREATE TABLE IF NOT EXISTS ctas_nation AS (SELECT * FROM nation);
DESCRIBE ctas_nation;

  Column   |  Type   | Extra | Comment
-----------+---------+-------+---------
 nationkey | bigint  |       |
 name      | varchar |       |
 regionkey | bigint  |       |
 comment   | varchar |       |
(4 rows)

We can simply add a new column to the Iceberg table by using ALTER TABLE statement. The following query adds a new column named zipcode to the table.

ALTER TABLE ctas_nation ADD COLUMN zipcode VARCHAR;
DESCRIBE ctas_nation;

  Column   |  Type   | Extra | Comment
-----------+---------+-------+---------
 nationkey | bigint  |       |
 name      | varchar |       |
 regionkey | bigint  |       |
 comment   | varchar |       |
 zipcode   | varchar |       |
(5 rows)

We can also rename the new column to another name, address:

ALTER TABLE ctas_nation RENAME COLUMN zipcode TO address;
DESCRIBE ctas_nation;

  Column   |  Type   | Extra | Comment
-----------+---------+-------+---------
 nationkey | bigint  |       |
 name      | varchar |       |
 regionkey | bigint  |       |
 comment   | varchar |       |
 address  | varchar |       |
(5 rows)

Finally, we can delete the new column. The table columns will be restored to the original state.

ALTER TABLE ctas_nation DROP COLUMN address;
DESCRIBE ctas_nation;

  Column   |  Type   | Extra | Comment
-----------+---------+-------+---------
 nationkey | bigint  |       |
 name      | varchar |       |
 regionkey | bigint  |       |
 comment   | varchar |       |
(4 rows)

Time Travel¶

Iceberg and Presto Iceberg connector support time travel via table snapshots identified by unique snapshot IDs. The snapshot IDs are stored in the $snapshots metadata table. You can rollback the state of a table to a previous snapshot ID. It also supports time travel query using SYSTEM_VERSION (VERSION) and SYSTEM_TIME (TIMESTAMP) options.

Example Queries¶

Similar to the example queries in SCHEMA EVOLUTION, create an Iceberg table named ctas_nation from the TPCH nation table:

USE iceberg.tpch;
CREATE TABLE IF NOT EXISTS ctas_nation AS (SELECT * FROM nation);
DESCRIBE ctas_nation;

  Column   |  Type   | Extra | Comment
-----------+---------+-------+---------
 nationkey | bigint  |       |
 name      | varchar |       |
 regionkey | bigint  |       |
 comment   | varchar |       |
(4 rows)

We can find snapshot IDs for the Iceberg table from the $snapshots metadata table.

SELECT snapshot_id FROM iceberg.tpch."ctas_nation$snapshots" ORDER BY committed_at;

     snapshot_id
---------------------
 5837462824399906536
(1 row)

For now, as we’ve just created the table, there’s only one snapshot ID. Let’s insert one row into the table and see the change in the snapshot IDs.

INSERT INTO ctas_nation VALUES(25, 'new country', 1, 'comment');
SELECT snapshot_id FROM iceberg.tpch."ctas_nation$snapshots" ORDER BY committed_at;

     snapshot_id
---------------------
 5837462824399906536
 5140039250977437531
(2 rows)

Now there’s a new snapshot (5140039250977437531) created as a new row is inserted into the table. The new row can be verified by running

SELECT * FROM ctas_nation WHERE name = 'new country';

 nationkey |    name     | regionkey | comment
-----------+-------------+-----------+---------
        25 | new country |         1 | comment
(1 row)

With the time travel feature, we can rollback to the previous state without the new row by calling iceberg.system.rollback_to_snapshot:

CALL iceberg.system.rollback_to_snapshot('tpch', 'ctas_nation', 5837462824399906536);

Now if we check the table again, we’ll find that the newly inserted row no longer exists as we’ve rolled back to the previous state.

SELECT * FROM ctas_nation WHERE name = 'new country';

 nationkey | name | regionkey | comment
-----------+------+-----------+---------
(0 rows)

Time Travel using VERSION (SYSTEM_VERSION) and TIMESTAMP (SYSTEM_TIME)¶

Use the Iceberg connector to access the historical data of a table. You can see how the table looked like at a certain point in time, even if the data has changed or been deleted since then.

// snapshot ID 5300424205832769799
INSERT INTO ctas_nation VALUES(10, 'united states', 1, 'comment');

// snapshot ID 6891257133877048303
INSERT INTO ctas_nation VALUES(20, 'canada', 2, 'comment');

// snapshot ID 705548372863208787
INSERT INTO ctas_nation VALUES(30, 'mexico', 3, 'comment');

// snapshot ID for first record
SELECT * FROM ctas_nation FOR VERSION AS OF 5300424205832769799;

// snapshot ID for first record using SYSTEM_VERSION
SELECT * FROM ctas_nation FOR SYSTEM_VERSION AS OF 5300424205832769799;

 nationkey |      name     | regionkey | comment
-----------+---------------+-----------+---------
        10 | united states |         1 | comment
(1 row)

// snapshot ID for second record using BEFORE clause to retrieve previous state
SELECT * FROM ctas_nation FOR SYSTEM_VERSION BEFORE 6891257133877048303;

 nationkey |      name     | regionkey | comment
-----------+---------------+-----------+---------
        10 | united states |         1 | comment
(1 row)

In above example, SYSTEM_VERSION can be used as an alias for VERSION.

You can access the historical data of a table using FOR TIMESTAMP AS OF TIMESTAMP. The query returns the table’s state using the table snapshot that is closest to the specified timestamp. In this example, SYSTEM_TIME can be used as an alias for TIMESTAMP.

// In following query, timestamp string is matching with second inserted record.
SELECT * FROM ctas_nation FOR TIMESTAMP AS OF TIMESTAMP '2023-10-17 13:29:46.822 America/Los_Angeles';
SELECT * FROM ctas_nation FOR TIMESTAMP AS OF TIMESTAMP '2023-10-17 13:29:46.822';

// Same example using SYSTEM_TIME as an alias for TIMESTAMP
SELECT * FROM ctas_nation FOR SYSTEM_TIME AS OF TIMESTAMP '2023-10-17 13:29:46.822 America/Los_Angeles';
SELECT * FROM ctas_nation FOR SYSTEM_TIME AS OF TIMESTAMP '2023-10-17 13:29:46.822';

 nationkey |      name     | regionkey | comment
-----------+---------------+-----------+---------
        10 | united states |         1 | comment
        20 | canada        |         2 | comment
(2 rows)

The option following FOR TIMESTAMP AS OF can accept any expression that returns a timestamp or timestamp with time zone value. For example, TIMESTAMP ‘2023-10-17 13:29:46.822 America/Los_Angeles’ and TIMESTAMP ‘2023-10-17 13:29:46.822’ are both valid timestamps. The first specifies the timestamp within the timezone America/Los_Angeles. The second will use the timestamp based on the user’s session timezone. In the following query, the expression CURRENT_TIMESTAMP returns the current timestamp with time zone value.

SELECT * FROM ctas_nation FOR TIMESTAMP AS OF CURRENT_TIMESTAMP;

 nationkey |      name     | regionkey | comment
-----------+---------------+-----------+---------
        10 | united states |         1 | comment
        20 | canada        |         2 | comment
        30 | mexico        |         3 | comment
(3 rows)

// In following query, timestamp string is matching with second inserted record.
// BEFORE clause returns first record which is less than timestamp of the second record.
SELECT * FROM ctas_nation FOR TIMESTAMP BEFORE TIMESTAMP '2023-10-17 13:29:46.822 America/Los_Angeles';
SELECT * FROM ctas_nation FOR TIMESTAMP BEFORE TIMESTAMP '2023-10-17 13:29:46.822';

 nationkey |      name     | regionkey | comment
-----------+---------------+-----------+---------
        10 | united states |         1 | comment
(1 row)

Querying branches and tags¶

Iceberg supports branches and tags which are named references to snapshots.

Query Iceberg table by specifying the branch name:

SELECT * FROM nation FOR SYSTEM_VERSION AS OF 'testBranch';

 nationkey |      name     | regionkey | comment
-----------+---------------+-----------+---------
        10 | united states |         1 | comment
        20 | canada        |         2 | comment
        30 | mexico        |         3 | comment
(3 rows)

Query Iceberg table by specifying the tag name:

SELECT * FROM nation FOR SYSTEM_VERSION AS OF 'testTag';

 nationkey |      name     | regionkey | comment
-----------+---------------+-----------+---------
        10 | united states |         1 | comment
        20 | canada        |         2 | comment
(3 rows)

Type mapping¶

PrestoDB and Iceberg have data types not supported by the other. When using Iceberg to read or write data, Presto changes each Iceberg data type to the corresponding Presto data type, and from each Presto data type to the comparable Iceberg data type. The following tables detail the specific type maps between PrestoDB and Iceberg.

Iceberg to PrestoDB type mapping¶

Map of Iceberg types to the relevant PrestoDB types:

No other types are supported.

PrestoDB to Iceberg type mapping¶

Map of PrestoDB types to the relevant Iceberg types:

No other types are supported.