RowSignature (druid-processing 0.19.0 API)

java.lang.Object
- org.apache.druid.segment.column.RowSignature

```
public class RowSignature
extends Object
```
Type signature for a row in a Druid datasource or query result. Rows have an ordering and every column has a defined type. This is a little bit of a fiction in the Druid world (where rows do not _actually_ have well defined types) but we do impose types for the SQL layer.

See Also:

which returns signatures for query results, which returns signatures for inline datasources

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class RowSignature.Builder

Nested Classes
Modifier and Type	Class and Description
`static class`	`RowSignature.Builder`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`static RowSignature.Builder`	`builder()`
`boolean`	`contains(String columnName)` Returns whether this signature contains a named column.
`static RowSignature`	`empty()`
`boolean`	`equals(Object o)`
`String`	`getColumnName(int columnNumber)` Returns the name of the column at position `columnNumber`.
`List<String>`	`getColumnNames()` Returns a list of column names in the order they appear in this signature.
`Optional<ValueType>`	`getColumnType(int columnNumber)` Returns the type of the column at position `columnNumber`, or empty if the type is unknown.
`Optional<ValueType>`	`getColumnType(String columnName)` Returns the type of the column named `columnName`, or empty if the type is unknown or the column does not exist.
`int`	`hashCode()`
`int`	`indexOf(String columnName)` Returns the first position of `columnName` in this row signature, or -1 if it does not appear.
`int`	`size()` Returns the number of columns in this signature.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Method Detail
  - builder
```
public static RowSignature.Builder builder()
```
  - empty
```
public static RowSignature empty()
```
  - getColumnName
```
public String getColumnName(int columnNumber)
```
    Returns the name of the column at position columnNumber.
    
    Throws:
    
    IndexOutOfBoundsException - if columnNumber is not within our row length
  - getColumnType
```
public Optional<ValueType> getColumnType(String columnName)
```
    Returns the type of the column named columnName, or empty if the type is unknown or the column does not exist.
  - getColumnType
```
public Optional<ValueType> getColumnType(int columnNumber)
```
    Returns the type of the column at position columnNumber, or empty if the type is unknown.
    
    Throws:
    
    IndexOutOfBoundsException - if columnNumber is not within our row length
  - getColumnNames
```
public List<String> getColumnNames()
```
    Returns a list of column names in the order they appear in this signature.
  - size
```
public int size()
```
    Returns the number of columns in this signature.
  - contains
```
public boolean contains(String columnName)
```
    Returns whether this signature contains a named column.
  - indexOf
```
public int indexOf(String columnName)
```
    Returns the first position of columnName in this row signature, or -1 if it does not appear. Note: the same column name may appear more than once in a signature; if it does, this method will return the first appearance.
  - equals
```
public boolean equals(Object o)
```
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class RowSignature

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

builder

empty

getColumnName

getColumnType

getColumnType

getColumnNames

size

contains

indexOf

equals

hashCode

toString