DeltaColumnBuilder¶

DeltaColumnBuilder is a builder interface to create columns programmatically.

DeltaColumnBuilder is created using DeltaTable.columnBuilder utility.

In the end, DeltaColumnBuilder is supposed to be built.

io.delta.tables Package¶

DeltaColumnBuilder belongs to io.delta.tables package.

import io.delta.tables.DeltaColumnBuilder

DeltaColumnBuilder takes the following to be created:

build(): StructField

Creates a StructField (Spark SQL) (possibly with some field metadata)

comment(
  comment: String): DeltaColumnBuilder

dataType(
  dataType: DataType): DeltaColumnBuilder
dataType(
  dataType: String): DeltaColumnBuilder

generatedAlwaysAs(
  expr: String): DeltaColumnBuilder

Registers the Generation Expression of this field

generatedAlwaysAsIdentity(): DeltaColumnBuilder // (1)!
generatedAlwaysAsIdentity(
  start: Long,
  step: Long): DeltaColumnBuilder

Sets the following:

Property	Value	Default Value
identityStart	`start`	1
identityStep	`step`	1
identityAllowExplicitInsert	`false`	(undefined)

generatedByDefaultAsIdentity(): DeltaColumnBuilder // (1)!
generatedByDefaultAsIdentity(
  start: Long,
  step: Long): DeltaColumnBuilder

Sets the following:

Property	Value	Default Value
identityStart	`start`	1
identityStep	`step`	1
identityAllowExplicitInsert	`true`	(undefined)

nullable(
  nullable: Boolean): DeltaColumnBuilder

generationExpr: Option[String] = None

DeltaColumnBuilder uses generationExpr internal registry for the generatedAlwaysAs expression.

When requested to build a StructField, DeltaColumnBuilder registers generationExpr under delta.generationExpression key in the metadata (of this field).

identityAllowExplicitInsert: Option[Boolean] = None

identityAllowExplicitInsert flag is used to indicate a call to the following methods:

Method	Value
generatedAlwaysAsIdentity	`false`
generatedByDefaultAsIdentity	`true`

identityAllowExplicitInsert is used to build a StructField.