Options¶

Delta Lake comes with options to fine-tune its uses. They can be defined using option method of the following:

• DataFrameReader (Spark SQL) and DataFrameWriter (Spark SQL) for batch queries
• DataStreamReader (Spark Structured Streaming) and DataStreamWriter (Spark Structured Streaming) for streaming queries
• SQL queries

Accessing Options¶

The options are available at runtime as DeltaOptions.

import org.apache.spark.sql.delta.DeltaOptions

assert(DeltaOptions.OVERWRITE_SCHEMA_OPTION == "overwriteSchema")

val options = new DeltaOptions(Map.empty[String, String], spark.sessionState.conf)
assert(options.failOnDataLoss, "failOnDataLoss should be enabled by default")

val options = new DeltaOptions(
  Map(DeltaOptions.OVERWRITE_SCHEMA_OPTION -> true.toString),
  spark.sessionState.conf)
assert(
  options.canOverwriteSchema,
  s"${DeltaOptions.OVERWRITE_SCHEMA_OPTION} should be enabled")

checkpointLocation¶

Checkpoint directory for storing checkpoint data of streaming queries (Spark Structured Streaming).

dataChange¶

Whether to write new data to the table or just rearrange data that is already part of the table. This option declares that the data being written by this job does not change any data in the table and merely rearranges existing data. This makes sure streaming queries reading from this table will not see any new changes

Used when:

• DeltaWriteOptionsImpl is requested for rearrangeOnly

excludeRegex¶

scala.util.matching.Regex to filter out the paths of FileActions

Default: (undefined)

Use DeltaOptions.excludeRegex to access the value

Used when:

• DeltaSourceBase is requested for the data (for a given DeltaSourceOffset)
• DeltaSourceCDCSupport is requested for the data

failOnDataLoss¶

Controls whether or not to fail loading a delta table when the earliest available version (in the _delta_log directory) is after the version requested

Default: true

Use DeltaOptions.failOnDataLoss to access the value

ignoreChanges¶

ignoreDeletes¶

ignoreFileDeletion¶

maxBytesPerTrigger¶

maxFilesPerTrigger¶

Maximum number of files (AddFiles) that DeltaSource is supposed to scan (read) in a streaming micro-batch (trigger)

Default: 1000

Must be at least 1

mergeSchema¶

Enables schema migration (and allows automatic schema merging during a write operation for WriteIntoDelta and DeltaSink)

Equivalent SQL Session configuration: spark.databricks.delta.schema.autoMerge.enabled

optimizeWrite¶

Enables...FIXME

overwriteSchema¶

Enables overwriting schema or change partitioning of a delta table during an overwrite write operation

Use DeltaOptions.canOverwriteSchema to access the value

path¶

(required) Directory on a Hadoop DFS-compliant file system with an optional time travel identifier

Default: (undefined)

queryName¶

readChangeFeed¶

Enables Change Data Feed while reading a delta table (CDC read)

Use DeltaOptions.readChangeFeed to access the value

Requires either startingVersion or startingTimestamp option

replaceWhere¶

Partition predicates (unless replaceWhere.dataColumns.enabled is enabled to allow for arbitrary non-partition data predicates)

Available as DeltaWriteOptions.replaceWhere

timestampAsOf¶

Timestamp of the version of a delta table for Time Travel

Mutually exclusive with versionAsOf option and the time travel identifier of the path option.

Used when:

• DeltaDataSource utility is used to get a DeltaTimeTravelSpec

userMetadata¶

Defines a user-defined commit metadata

Take precedence over spark.databricks.delta.commitInfo.userMetadata

Available by inspecting CommitInfos using DESCRIBE HISTORY or DeltaTable.history.

versionAsOf¶

Version of a delta table for Time Travel

Must be castable to a long number

Mutually exclusive with timestampAsOf option and the time travel identifier of the path option.

Used when:

• DeltaDataSource utility is used to get a DeltaTimeTravelSpec