PreprocessTableMerge Logical Resolution Rule¶

PreprocessTableMerge is a post-hoc logical resolution rule (Spark SQL) to resolve DeltaMergeInto logical commands (in a logical query plan) into MergeIntoCommands.

PreprocessTableMerge is injected (installed) into a SparkSession using DeltaSparkSessionExtension.

Creating Instance¶

PreprocessTableMerge takes the following to be created:

• SQLConf (Spark SQL)

PreprocessTableMerge is created when:

• DeltaSparkSessionExtension is requested to register Delta SQL support
• DeltaMergeBuilder is requested to execute

Executing Rule¶

apply(
  plan: LogicalPlan): LogicalPlan

apply is part of the Rule (Spark SQL) abstraction.

In summary, apply resolves (replaces) DeltaMergeInto logical commands (in a logical query plan) into corresponding MergeIntoCommands.

Internally, apply...FIXME