DeltaConfigs (DeltaConfigsBase)¶

DeltaConfigs holds the table properties that can be set on a delta table.

Configuration Properties¶

appendOnly¶

Whether a delta table is append-only (true) or not (false). When enabled, a table allows appends only and no updates or deletes.

Default: false

Used when:

• DeltaLog is requested to assertRemovable (that in turn uses DeltaErrors utility to modifyAppendOnlyTableException)
• Protocol utility is used to requiredMinimumProtocol

autoOptimize¶

Whether this delta table will automagically optimize the layout of files during writes.

Default: false

checkpointInterval¶

How often to checkpoint the state of a delta table (at the end of transaction commit)

Default: 10

checkpointRetentionDuration¶

How long to keep checkpoint files around before deleting them

Default: interval 2 days

The most recent checkpoint is never deleted. It is acceptable to keep checkpoint files beyond this duration until the next calendar day.

checkpoint.writeStatsAsJson¶

Controls whether to write file statistics in the checkpoint in JSON format as the stats column.

Default: true

checkpoint.writeStatsAsStruct¶

Controls whether to write file statistics in the checkpoint in the struct format in the stats_parsed column and partition values as a struct as partitionValues_parsed

Default: undefined (Option[Boolean])

compatibility.symlinkFormatManifest.enabled¶

Whether to register the GenerateSymlinkManifest post-commit hook while committing a transaction or not

Default: false

dataSkippingNumIndexedCols¶

The number of columns to collect stats on for data skipping. -1 means collecting stats for all columns.

Default: 32

Must be larger than or equal to -1.

Used when:

• Snapshot is requested for the maximum number of indexed columns
• TransactionalWrite is requested to write data out

deletedFileRetentionDuration¶

How long to keep logically deleted data files around before deleting them physically (to prevent failures in stale readers after compactions or partition overwrites)

Default: interval 1 week

enableExpiredLogCleanup¶

Whether to clean up expired log files and checkpoints

Default: true

enableFullRetentionRollback¶

Controls whether or not a delta table can be rolled back to any point within logRetentionDuration. When disabled, the table can be rolled back checkpointRetentionDuration only.

Default: true

logRetentionDuration¶

How long to keep obsolete logs around before deleting them. Delta can keep logs beyond the duration until the next calendar day to avoid constantly creating checkpoints.

Default: interval 30 days (CalendarInterval)

minReaderVersion¶

The protocol reader version

Default: 1

This property is not stored as a table property in the Metadata action. It is stored as its own action. Having it modelled as a table property makes it easier to upgrade, and view the version.

minWriterVersion¶

The protocol reader version

Default: 3

This property is not stored as a table property in the Metadata action. It is stored as its own action. Having it modelled as a table property makes it easier to upgrade, and view the version.

randomizeFilePrefixes¶

Whether to use a random prefix in a file path instead of partition information (may be required for very high volume S3 calls to better be partitioned across S3 servers)

Default: false

randomPrefixLength¶

The length of the random prefix in a file path for randomizeFilePrefixes

Default: 2

sampleRetentionDuration¶

How long to keep delta sample files around before deleting them

Default: interval 7 days

Building Configuration¶

buildConfig[T](
  key: String,
  defaultValue: String,
  fromString: String => T,
  validationFunction: T => Boolean,
  helpMessage: String,
  minimumProtocolVersion: Option[Protocol] = None): DeltaConfig[T]

buildConfig creates a DeltaConfig for the given key (with delta prefix added) and adds it to the entries internal registry.

buildConfig is used to define all of the configuration properties in a type-safe way and (as a side effect) register them with the system-wide entries internal registry.

System-Wide Configuration Entries Registry¶

entries: HashMap[String, DeltaConfig[_]]

DeltaConfigs utility (a Scala object) uses entries internal registry of DeltaConfigs by their key.

New entries are added in buildConfig.

entries is used when:

• validateConfigurations
• mergeGlobalConfigs
• normalizeConfigKey and normalizeConfigKeys

mergeGlobalConfigs Utility¶

mergeGlobalConfigs(
  sqlConfs: SQLConf,
  tableConf: Map[String, String],
  protocol: Protocol): Map[String, String]

mergeGlobalConfigs finds all spark.databricks.delta.properties.defaults-prefixed configuration properties among the entries.

mergeGlobalConfigs is used when:

• OptimisticTransactionImpl is requested to withGlobalConfigDefaults
• InitialSnapshot is created

validateConfigurations Utility¶

validateConfigurations(
  configurations: Map[String, String]): Map[String, String]

validateConfigurations...FIXME

validateConfigurations is used when:

• DeltaCatalog is requested to verifyTableAndSolidify and alterTable

normalizeConfigKeys Utility¶

normalizeConfigKeys(
  propKeys: Seq[String]): Seq[String]

normalizeConfigKeys...FIXME

normalizeConfigKeys is used when:

• AlterTableUnsetPropertiesDeltaCommand is executed

spark.databricks.delta.properties.defaults Prefix¶

DeltaConfigs uses spark.databricks.delta.properties.defaults prefix for global configuration properties.