```
public interface DataSourceMetadata
```
The DataSourceMetadata class contains all the metadata for a column for query execution purpose.

Method Summary

Modifier and Type	Method	Description
`int`	`getCardinality()`	Returns the cardinality of the column, `-1` if not applicable
`default FieldSpec.DataType`	`getDataType()`	Returns the data type of the column.
`FieldSpec`	`getFieldSpec()`	Returns the field spec of the column.
`int`	`getMaxNumValuesPerMVEntry()`	Returns the maximum number of values for each multi-value entry of the multi-value column.
`Comparable`	`getMaxValue()`	Returns the maximum value of the column, or `null` if it is not available.
`Comparable`	`getMinValue()`	Returns the minimum value of the column, or `null` if it is not available.
`int`	`getNumDocs()`	Returns the number of documents of the column.
`int`	`getNumValues()`	Returns the number of values of the column.
`PartitionFunction`	`getPartitionFunction()`	Returns the partition function of the column, or `null` if the column is not partitioned.
`Set<Integer>`	`getPartitions()`	Returns the partitions the column belongs to, or `null` if the column is not partitioned.
`default boolean`	`isSingleValue()`	Returns `true` if the column is single-valued, `false` otherwise.
`boolean`	`isSorted()`	Returns `true` if the column is sorted, `false` otherwise.

- Method Detail
  - getFieldSpec
```
FieldSpec getFieldSpec()
```
    Returns the field spec of the column.
  - getDataType
```
default FieldSpec.DataType getDataType()
```
    Returns the data type of the column.
  - isSingleValue
```
default boolean isSingleValue()
```
    Returns true if the column is single-valued, false otherwise.
  - isSorted
```
boolean isSorted()
```
    Returns true if the column is sorted, false otherwise. The result of this method cannot be trusted if null handling is enabled.
  - getNumDocs
```
int getNumDocs()
```
    Returns the number of documents of the column.
  - getNumValues
```
int getNumValues()
```
    Returns the number of values of the column. For single-value column, number of values always equals to number of documents; for multi-value column, each document (multi-value entry) may contain multiple values.
  - getMaxNumValuesPerMVEntry
```
int getMaxNumValuesPerMVEntry()
```
    Returns the maximum number of values for each multi-value entry of the multi-value column. Returns -1 for single-value column.
  - getMinValue
```
@Nullable
Comparable getMinValue()
```
    Returns the minimum value of the column, or null if it is not available.
  - getMaxValue
```
@Nullable
Comparable getMaxValue()
```
    Returns the maximum value of the column, or null if it is not available.
  - getPartitionFunction
```
@Nullable
PartitionFunction getPartitionFunction()
```
    Returns the partition function of the column, or null if the column is not partitioned.
  - getPartitions
```
@Nullable
Set<Integer> getPartitions()
```
    Returns the partitions the column belongs to, or null if the column is not partitioned.
  - getCardinality
```
int getCardinality()
```
    Returns the cardinality of the column, -1 if not applicable

Interface DataSourceMetadata

Method Summary

Method Detail

getFieldSpec

getDataType

isSingleValue

isSorted

getNumDocs

getNumValues

getMaxNumValuesPerMVEntry

getMinValue

getMaxValue

getPartitionFunction

getPartitions

getCardinality