Interface RowReader

All Superinterfaces:

AutoCloseable, FieldAccessor, StructAccessor

public interface RowReader
extends StructAccessor, AutoCloseable

Provides row-oriented iteration over a Parquet file.

A RowReader is a stateful, mutable view providing access to the current row in the iterator. The values returned by its accessors change between calls of next().

Usage example:

try (RowReader rowReader = fileReader.rowReader()) {
    while (rowReader.hasNext()) {
        rowReader.next();
        long id = rowReader.getLong("id");
        PqStruct address = rowReader.getStruct("address");
        String city = address.getString("city");
    }
}

Method Summary

Modifier and Type	Method	Description
void	close()
static RowReader	create(dev.hardwood.internal.reader.RowGroupIterator rowGroupIterator, FileSchema schema, ProjectedSchema projectedSchema, dev.hardwood.internal.reader.HardwoodContextImpl context, dev.hardwood.internal.predicate.ResolvedPredicate filter, long maxRows)	Creates a RowReader for the given pipeline components.
boolean	hasNext()	Check if there are more rows to read.
void	next()	Advance to the next row.

Methods inherited from interface FieldAccessor

getBinary, getBoolean, getDate, getDecimal, getDouble, getFieldCount, getFieldName, getFloat, getInt, getInterval, getLong, getRawValue, getString, getTime, getTimestamp, getUuid, getValue, getVariant, isNull

Methods inherited from interface StructAccessor

getBinary, getBoolean, getDate, getDecimal, getDouble, getFloat, getInt, getInterval, getList, getList, getLong, getMap, getMap, getRawValue, getString, getStruct, getStruct, getTime, getTimestamp, getUuid, getValue, getVariant, isNull

Method Details

create

static RowReader create(dev.hardwood.internal.reader.RowGroupIterator rowGroupIterator,
 FileSchema schema,
 ProjectedSchema projectedSchema,
 dev.hardwood.internal.reader.HardwoodContextImpl context,
 dev.hardwood.internal.predicate.ResolvedPredicate filter,
 long maxRows)

Creates a RowReader for the given pipeline components.

Selects FlatRowReader for flat schemas and NestedRowReader for nested schemas. Wraps with FilteredRowReader when a filter is present.

Parameters:

rowGroupIterator - initialized iterator over row groups

schema - file schema

projectedSchema - column projection

context - hardwood context

filter - resolved predicate, or null for no filtering

maxRows - maximum rows (0 = unlimited)

hasNext

boolean hasNext()

Check if there are more rows to read.

Returns:

true if there are more rows available

next

void next()

Advance to the next row. Must be called before accessing row data.

Throws:

NoSuchElementException - if no more rows are available

close

void close()

Specified by:

close in interface AutoCloseable