Configuration

Table properties

Iceberg tables support table properties to configure table behavior, like the default split size for readers.

Read properties

Property Default Description
read.split.target-size 134217728 (128 MB) Target size when combining data input splits
read.split.metadata-target-size 33554432 (32 MB) Target size when combining metadata input splits
read.split.planning-lookback 10 Number of bins to consider when combining input splits
read.split.open-file-cost 4194304 (4 MB) The estimated cost to open a file, used as a minimum weight when combining splits.

Write properties

Property Default Description
write.format.default parquet Default file format for the table; parquet, avro, or orc
write.parquet.row-group-size-bytes 134217728 (128 MB) Parquet row group size
write.parquet.page-size-bytes 1048576 (1 MB) Parquet page size
write.parquet.dict-size-bytes 2097152 (2 MB) Parquet dictionary page size
write.parquet.compression-codec gzip Parquet compression codec
write.parquet.compression-level null Parquet compression level
write.avro.compression-codec gzip Avro compression codec
write.location-provider.impl null Optional custom implemention for LocationProvider
write.metadata.compression-codec none Metadata compression codec; none or gzip
write.metadata.metrics.default truncate(16) Default metrics mode for all columns in the table; none, counts, truncate(length), or full
write.metadata.metrics.column.col1 (not set) Metrics mode for column ‘col1’ to allow per-column tuning; none, counts, truncate(length), or full
write.target-file-size-bytes Long.MAX_VALUE Controls the size of files generated to target about this many bytes
write.distribution-mode none Defines distribution of write data: none: don’t shuffle rows; hash: hash distribute by partition key ; range: range distribute by partition key or sort key if table has an SortOrder
write.wap.enabled false Enables write-audit-publish writes
write.summary.partition-limit 0 Includes partition-level summary stats in snapshot summaries if the changed partition count is less than this limit
write.metadata.delete-after-commit.enabled false Controls whether to delete the oldest version metadata files after commit
write.metadata.previous-versions-max 100 The max number of previous version metadata files to keep before deleting after commit
write.spark.fanout.enabled false Enables Partitioned-Fanout-Writer writes in Spark

Table behavior properties

Property Default Description
commit.retry.num-retries 4 Number of times to retry a commit before failing
commit.retry.min-wait-ms 100 Minimum time in milliseconds to wait before retrying a commit
commit.retry.max-wait-ms 60000 (1 min) Maximum time in milliseconds to wait before retrying a commit
commit.retry.total-timeout-ms 1800000 (30 min) Maximum time in milliseconds to wait before retrying a commit
commit.manifest.target-size-bytes 8388608 (8 MB) Target size when merging manifest files
commit.manifest.min-count-to-merge 100 Minimum number of manifests to accumulate before merging
commit.manifest-merge.enabled true Controls whether to automatically merge manifests on writes
history.expire.max-snapshot-age-ms 432000000 (5 days) Default max age of snapshots to keep while expiring snapshots
history.expire.min-snapshots-to-keep 1 Default min number of snapshots to keep while expiring snapshots

Compatibility flags

Property Default Description
compatibility.snapshot-id-inheritance.enabled false Enables committing snapshots without explicit snapshot IDs

Catalog properties

Iceberg catalogs support using catalog properties to configure catalog behaviors. Here is a list of commonly used catalog properties:

Property Default Description
catalog-impl null a custom Catalog implementation to use by an engine
io-impl null a custom FileIO implementation to use in a catalog
warehouse null the root path of the data warehouse
uri null a URI string, such as Hive metastore URI
clients 2 client pool size

HadoopCatalog and HiveCatalog can access the properties in their constructors. Any other custom catalog can access the properties by implementing Catalog.initialize(catalogName, catalogProperties). The properties can be manually constructed or passed in from a compute engine like Spark or Flink. Spark uses its session properties as catalog properties, see more details in the Spark configuration section. Flink passes in catalog properties through CREATE CATALOG statement, see more details in the Flink section.

Lock catalog properties

Here are the catalog properties related to locking. They are used by some catalog implementations to control the locking behavior during commits.

Property Default Description
lock-impl null a custom implementation of the lock manager, the actual interface depends on the catalog used
lock.table null an auxiliary table for locking, such as in AWS DynamoDB lock manager
lock.acquire-interval-ms 5 seconds the interval to wait between each attempt to acquire a lock
lock.acquire-timeout-ms 3 minutes the maximum time to try acquiring a lock
lock.heartbeat-interval-ms 3 seconds the interval to wait between each heartbeat after acquiring a lock
lock.heartbeat-timeout-ms 15 seconds the maximum time without a heartbeat to consider a lock expired

Hadoop configuration

The following properties from the Hadoop configuration are used by the Hive Metastore connector.

Property Default Description
iceberg.hive.client-pool-size 5 The size of the Hive client pool when tracking tables in HMS
iceberg.hive.lock-timeout-ms 180000 (3 min) Maximum time in milliseconds to acquire a lock
iceberg.hive.lock-check-min-wait-ms 50 Minimum time in milliseconds to check back on the status of lock acquisition
iceberg.hive.lock-check-max-wait-ms 5000 Maximum time in milliseconds to check back on the status of lock acquisition

Note: iceberg.hive.lock-check-max-wait-ms should be less than the transaction timeout of the Hive Metastore (hive.txn.timeout or metastore.txn.timeout in the newer versions). Otherwise, the heartbeats on the lock (which happens during the lock checks) would end up expiring in the Hive Metastore before the lock is retried from Iceberg.