DeltaTableV2¶

DeltaTableV2 is a logical representation of a writable Delta table.

Creating Instance¶

DeltaTableV2 takes the following to be created:

SparkSession (Spark SQL)
Path (Hadoop HDFS)
Optional Catalog Metadata (Spark SQL)
Optional Table ID
Optional DeltaTimeTravelSpec
Options
CDC Options (empty in Delta Lake OSS)

DeltaTableV2 is created when:

DeltaTable utility is used to forPath and forName
DeltaCatalog is requested to load a table
DeltaDataSource is requested to load a table or create a table relation

Options¶

DeltaTableV2 can be given options (as a Map[String, String]). Options are empty by default.

The options are defined when DeltaDataSource is requested for a relation with spark.databricks.delta.loadFileSystemConfigsFromDataFrameOptions configuration property enabled.

The options are used for the following:

Looking up path or paths options
Creating the DeltaLog

DeltaLog¶

DeltaTableV2 creates a DeltaLog for the rootPath and the given options.

Table¶

DeltaTableV2 is a Table (Spark SQL).

SupportsWrite¶

DeltaTableV2 is a SupportsWrite (Spark SQL).

V2TableWithV1Fallback¶

DeltaTableV2 is a V2TableWithV1Fallback (Spark SQL).

DeltaTimeTravelSpec¶

DeltaTableV2 may be given a DeltaTimeTravelSpec when created.

DeltaTimeTravelSpec is assumed not to be defined by default (None).

DeltaTableV2 is given a DeltaTimeTravelSpec when:

DeltaDataSource is requested for a BaseRelation

DeltaTimeTravelSpec is used for timeTravelSpec.

Properties¶

properties(): Map[String, String]

properties is part of the Table (Spark SQL) abstraction.

properties requests the Snapshot for the table properties and adds the following:

Name	Value
`provider`	`delta`
`location`	path
`comment`	description (of the Metadata) if available
`Type`	table type of the CatalogTable if available

Table Capabilities¶

capabilities(): Set[TableCapability]

capabilities is part of the Table (Spark SQL) abstraction.

capabilities is the following:

ACCEPT_ANY_SCHEMA (Spark SQL)
BATCH_READ (Spark SQL)
V1_BATCH_WRITE (Spark SQL)
OVERWRITE_BY_FILTER (Spark SQL)
TRUNCATE (Spark SQL)

Creating WriteBuilder¶

newWriteBuilder(
  info: LogicalWriteInfo): WriteBuilder

newWriteBuilder is part of the SupportsWrite (Spark SQL) abstraction.

newWriteBuilder creates a WriteIntoDeltaBuilder (for the DeltaLog and the options from the LogicalWriteInfo).

Snapshot¶

snapshot: Snapshot

DeltaTableV2 has a Snapshot. In other words, DeltaTableV2 represents a Delta table at a specific version.

Scala lazy value

snapshot is a Scala lazy value and is initialized once when first accessed. Once computed it stays unchanged.

DeltaTableV2 uses the DeltaLog to load it at a given version (based on the optional timeTravelSpec) or update to the latest version.

snapshot is used when DeltaTableV2 is requested for the schema, partitioning and properties.

DeltaTimeTravelSpec¶

timeTravelSpec: Option[DeltaTimeTravelSpec]

DeltaTableV2 may have a DeltaTimeTravelSpec specified that is either given or extracted from the path (for timeTravelByPath).

timeTravelSpec throws an AnalysisException when timeTravelOpt and timeTravelByPath are both defined:

Cannot specify time travel in multiple formats.

timeTravelSpec is used when DeltaTableV2 is requested for a Snapshot and BaseRelation.

DeltaTimeTravelSpec by Path¶

timeTravelByPath: Option[DeltaTimeTravelSpec]

Scala lazy value

timeTravelByPath is a Scala lazy value and is initialized once when first accessed. Once computed it stays unchanged.

timeTravelByPath is undefined when CatalogTable is defined.

With no CatalogTable defined, DeltaTableV2 parses the given Path for the timeTravelByPath (that resolvePath under the covers).

Converting to Insertable HadoopFsRelation¶

toBaseRelation: BaseRelation

toBaseRelation verifyAndCreatePartitionFilters for the Path, the current Snapshot and partitionFilters.

In the end, toBaseRelation requests the DeltaLog for an insertable HadoopFsRelation.

toBaseRelation is used when:

DeltaDataSource is requested to createRelation
DeltaRelation utility is used to fromV2Relation