org.apache.drill.exec.physical.impl.scan.v3.file

Class ImplicitColumnResolver

java.lang.Object

org.apache.drill.exec.physical.impl.scan.v3.file.ImplicitColumnResolver

public class ImplicitColumnResolver
extends Object

Manages the resolution of implicit file metadata and partition columns. Parses the file metadata columns from the projection list. Creates a parse result which drives loading data into vectors. Supports renaming the columns via session options.

Lifecycle:

• At the start of the scan, the parser looks for implicit and partition columns in the scan schema, resolving matching columns to be implicit columns, and building up a description of those columns for use later.
• If the projection list contains a wildcard, it can also contain implicit columns. If running in legacy mode, inserts partition columns when the query contains a wildcard.
• On each file (on each reader), the parse result allows generating actual values for each column, which are then written into the corresponding value vectors.

Assumes that the partition count is fixed at runtime; that it is determined at plan time and provided in the plan. This ensures that the schema is stable across readers: even a reader at the top-most partition will produce columns for all partitions if using legacy mode wildcard expansion.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ImplicitColumnResolver.ImplicitColumnOptions
static class	ImplicitColumnResolver.ParseResult The result of scanning the scan output schema to identify implicit and partition columns.

Field Summary

Fields

Modifier and Type	Field and Description
static TypeProtos.MajorType	IMPLICIT_COL_TYPE
static TypeProtos.MajorType	OPTIONAL_INTERNAL_COL_TYPE
static TypeProtos.MajorType	PARTITION_COL_TYPE

Constructor Summary

Constructors

Constructor and Description
ImplicitColumnResolver(ImplicitColumnResolver.ImplicitColumnOptions options, CustomErrorContext errorContext)

Method Summary

Modifier and Type	Method and Description
ImplicitColumnResolver.ParseResult	parse(ScanSchemaTracker tracker)
String	partitionName(int partition)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

IMPLICIT_COL_TYPE

public static final TypeProtos.MajorType IMPLICIT_COL_TYPE

PARTITION_COL_TYPE

public static final TypeProtos.MajorType PARTITION_COL_TYPE

OPTIONAL_INTERNAL_COL_TYPE

public static final TypeProtos.MajorType OPTIONAL_INTERNAL_COL_TYPE

Constructor Detail

ImplicitColumnResolver

public ImplicitColumnResolver(ImplicitColumnResolver.ImplicitColumnOptions options,
                              CustomErrorContext errorContext)

Method Detail

parse

public ImplicitColumnResolver.ParseResult parse(ScanSchemaTracker tracker)

partitionName

public String partitionName(int partition)