public class OffsetVectorWriterImpl extends AbstractFixedWidthWriter implements OffsetVectorWriter
Note that the lastWriteIndex tracked here corresponds to the data values; it is one less than the actual offset vector last write index due to the nature of offset vector layouts. The selection of last write index basis makes roll-over processing easier as only this writer need know about the +1 translation required for writing.
The states illustrated in the base class apply here as well, remembering that the end offset for a row (or array position) is written one ahead of the vector index.
The vector index does create an interesting dynamic for the child writers. From the child writer's perspective, the states described in the super class are the only states of interest. Here we want to take the perspective of the parent.
The offset vector is an implementation of a repeat level. A repeat level can occur for a single array, or for a collection of columns within a repeated map. (A repeat level also occurs for variable-width fields, but this is a bit harder to see, so let's ignore that for now.)
The key point to realize is that each repeat level introduces an isolation level in terms of indexing. That is, empty values in the outer level have no affect on indexing in the inner level. In fact, the nature of a repeated outer level means that there are no empties in the inner level.
To illustrate:
Offset Vector Data Vector Indexes
lw, v > | 10 | - - - - - > | X | 10
| 12 | - - + | X | < lw' 11
| | + - - > | | < v' 12
From the data vector's perspective, its last-write (lw') reflects the last element written. If this is an array of scalars, then the write index is automatically incremented, as illustrated by v'. (For map arrays, the index must be incremented by calling save() on the map array writer.)
Suppose the client now skips some arrays:
Offset Vector Data Vector
lw > | 10 | - - - - - > | X | 10
| 12 | - - + | X | < lw' 11
| | + - - > | | < v' 12
| | | | 13
v > | | | | 14
The client now writes a three-element vector:
Offset Vector Data Vector
| 10 | - - - - - > | X | 10
| 12 | - - + | X | 11
| 12 | - - + - - > | Y | 12
| 12 | - - + | Y | 13
lw, v > | 12 | - - + | Y | < lw' 14
| 15 | - - - - - > | | < v' 15
Note that, for an array of scalars, when overflow occurs, we need only worry about two states in the data vector. Either data has been written for the row (as in the third example above), and so must be moved to the roll-over vector, or no data has been written and no move is needed. We never have to worry about missing values because the cannot occur in the data vector.
See ObjectArrayWriter for information about arrays of
maps (arrays of multiple columns.)
The second way to fill empties is in the data vector. The data vector may choose
to fill the four "empty" slots with a value, say "X". In this case, it is up to
the data vector to fill in the values, calling into this vector to set each
offset. Note that when doing this, the calls are a bit different than for writing
a regular value because we want to write at the "last write position", not the
current row position. See BaseVarWidthWriter for an example.
AbstractFixedWidthWriter.BaseFixedWidthWriter, AbstractFixedWidthWriter.BaseIntWriterAbstractScalarWriterImpl.ScalarObjectWriterWriterEvents.ColumnWriterListener, WriterEvents.State| Modifier and Type | Field and Description |
|---|---|
protected int |
nextOffset
Cached value of the end offset for the current value.
|
lastWriteIndexcapacity, drillBuf, emptyValue, listener, MIN_BUFFER_SIZEschema, vectorIndex| Constructor and Description |
|---|
OffsetVectorWriterImpl(UInt4Vector vector) |
| Modifier and Type | Method and Description |
|---|---|
void |
copy(ColumnReader from)
Copy a single value from the given reader, which must be of the
same type as this writer.
|
void |
dump(HierarchicalFormatter format) |
protected void |
fillEmpties(int fillCount) |
void |
fillOffset(int newOffset) |
int |
nextOffset() |
void |
postRollover()
The vectors backing this writer rolled over.
|
int |
prepareFill() |
protected int |
prepareWrite()
Return the write offset, which is one greater than the index reported
by the vector index.
|
void |
preRollover()
The vectors backing this vector are about to roll over.
|
protected void |
realloc(int size) |
void |
restartRow()
During a writer to a row, rewind the the current index position to
restart the row.
|
void |
reviseOffset(int newOffset) |
int |
rowStartOffset() |
void |
setDefaultValue(Object value)
Set the default value to be used to fill empties for this writer.
|
void |
setNextOffset(int newOffset) |
void |
setValue(Object value)
Write value to a vector as a Java object of the "native" type for
the column.
|
void |
setValueCount(int valueCount) |
void |
skipNulls() |
void |
startRow()
Start a new row.
|
void |
startWrite()
Start a write (batch) operation.
|
ValueType |
valueType()
Describe the type of the value.
|
BaseDataValueVector |
vector() |
int |
width() |
endWrite, lastWriteIndex, mandatoryResize, resize, setBuffer, setLastWriteIndexappendBytes, bindListener, bindSchema, canExpand, nullable, overflowed, setBoolean, setBytes, setDate, setDecimal, setDouble, setFloat, setInt, setLong, setNull, setPeriod, setString, setTime, setTimestampbindIndex, endArrayValue, isProjected, rowStartIndex, saveRow, schema, type, writeIndexconversionError, extendedType, setObject, toStringclone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitextendedTypeisProjected, nullable, schema, setNull, setObject, typeappendBytes, setBoolean, setBytes, setDate, setDecimal, setDouble, setFloat, setInt, setLong, setNull, setPeriod, setString, setTime, setTimestampbindIndex, bindListener, endArrayValue, endWrite, saveRowlastWriteIndex, rowStartIndex, writeIndexprotected int nextOffset
@endValue().public OffsetVectorWriterImpl(UInt4Vector vector)
public BaseDataValueVector vector()
vector in class AbstractScalarWriterImplpublic int width()
width in class AbstractFixedWidthWriterprotected void realloc(int size)
realloc in class BaseScalarWriterpublic ValueType valueType()
ScalarWritervalueType in interface ScalarWriterpublic void startWrite()
WriterEventsstartWrite in interface WriterEventsstartWrite in class AbstractFixedWidthWriterpublic int nextOffset()
nextOffset in interface OffsetVectorWriterpublic int rowStartOffset()
rowStartOffset in interface OffsetVectorWriterpublic void startRow()
WriterEventsWriterEvents.restartRow() instead.startRow in interface WriterEventsstartRow in class AbstractScalarWriterImplprotected final int prepareWrite()
public final int prepareFill()
protected final void fillEmpties(int fillCount)
fillEmpties in class AbstractFixedWidthWriterpublic final void setNextOffset(int newOffset)
setNextOffset in interface OffsetVectorWriterpublic final void reviseOffset(int newOffset)
public final void fillOffset(int newOffset)
public final void setValue(Object value)
ValueWriterPrimarily to be used when the code already knows the object type.
setValue in interface ValueWritervalue - a value that matches the primary setter above, or null
to set the column to nullfor the generic casepublic void skipNulls()
skipNulls in class AbstractFixedWidthWriterpublic void restartRow()
WriterEventsrestartRow in interface WriterEventsrestartRow in class AbstractFixedWidthWriterpublic void preRollover()
WriterEventspreRollover in interface WriterEventspreRollover in class AbstractFixedWidthWriterpublic void postRollover()
WriterEventspostRollover in interface WriterEventspostRollover in class AbstractFixedWidthWriterpublic void setValueCount(int valueCount)
setValueCount in class AbstractFixedWidthWriterpublic void dump(HierarchicalFormatter format)
dump in interface OffsetVectorWriterdump in interface WriterEventsdump in class AbstractFixedWidthWriterpublic void setDefaultValue(Object value)
ScalarWritersetDefaultValue in interface ScalarWritervalue - the value to set. Cannot be null. The type of the value
must match that legal for ValueWriter.setValue(Object)public void copy(ColumnReader from)
ColumnWritercopy in interface ColumnWriterfrom - reader to provide the dataCopyright © 1970 The Apache Software Foundation. All rights reserved.