org.apache.cassandra.db.rows

Class Cells

java.lang.Object

org.apache.cassandra.db.rows.Cells

public abstract class Cells
extends java.lang.Object

Static methods to work on cells.

Method Summary

Modifier and Type	Method and Description
static void	collectStats(Cell cell, PartitionStatisticsCollector collector) Collect statistics ont a given cell.
static long	reconcile(Cell existing, Cell update, DeletionTime deletion, Row.Builder builder, int nowInSec) Reconciles/merges two cells, one being an update to an existing cell, yielding index updates if appropriate.
static Cell	reconcile(Cell c1, Cell c2, int nowInSec) Reconciles/merge two cells.
static long	reconcileComplex(ColumnDefinition column, java.util.Iterator<Cell> existing, java.util.Iterator<Cell> update, DeletionTime deletion, Row.Builder builder, int nowInSec) Computes the reconciliation of a complex column given its pre-existing cells and the ones it is updated with, and generating index update if appropriate.

Methods inherited from class java.lang.Object

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

Method Detail

collectStats

public static void collectStats(Cell cell,
                                PartitionStatisticsCollector collector)

Collect statistics ont a given cell.

Parameters:

cell - the cell for which to collect stats.

collector - the stats collector.

reconcile

public static long reconcile(Cell existing,
                             Cell update,
                             DeletionTime deletion,
                             Row.Builder builder,
                             int nowInSec)

Reconciles/merges two cells, one being an update to an existing cell, yielding index updates if appropriate.

Note that this method assumes that the provided cells can meaningfully be reconciled together, that is that those cells are for the same row and same column (and same cell path if the column is complex).

Also note that which cell is provided as existing and which is provided as update matters for index updates.

Parameters:

existing - the pre-existing cell, the one that is updated. This can be null if this reconciliation correspond to an insertion.

update - the newly added cell, the update. This can be null out of convenience, in which case this function simply copy existing to writer.

deletion - the deletion time that applies to the cells being considered. This deletion time may delete both existing or update.

builder - the row builder to which the result of the reconciliation is written.

nowInSec - the current time in seconds (which plays a role during reconciliation because deleted cells always have precedence on timestamp equality and deciding if a cell is a live or not depends on the current time due to expiring cells).

Returns:

the timestamp delta between existing and update, or Long.MAX_VALUE if one of them is null or deleted by deletion).

reconcile

public static Cell reconcile(Cell c1,
                             Cell c2,
                             int nowInSec)

Reconciles/merge two cells.

Note that this method assumes that the provided cells can meaningfully be reconciled together, that is that cell are for the same row and same column (and same cell path if the column is complex).

This method is commutative over it's cells arguments: reconcile(a, b, n) == reconcile(b, a, n).

Parameters:

c1 - the first cell participating in the reconciliation.

c2 - the second cell participating in the reconciliation.

nowInSec - the current time in seconds (which plays a role during reconciliation because deleted cells always have precedence on timestamp equality and deciding if a cell is a live or not depends on the current time due to expiring cells).

Returns:

a cell corresponding to the reconciliation of c1 and c2. For non-counter cells, this will always be either c1 or c2, but for counter cells this can be a newly allocated cell.

reconcileComplex

public static long reconcileComplex(ColumnDefinition column,
                                    java.util.Iterator<Cell> existing,
                                    java.util.Iterator<Cell> update,
                                    DeletionTime deletion,
                                    Row.Builder builder,
                                    int nowInSec)

Computes the reconciliation of a complex column given its pre-existing cells and the ones it is updated with, and generating index update if appropriate.

Note that this method assumes that the provided cells can meaningfully be reconciled together, that is that the cells are for the same row and same complex column.

Also note that which cells is provided as existing and which are provided as update matters for index updates.

Parameters:

column - the complex column the cells are for.

existing - the pre-existing cells, the ones that are updated. This can be null if this reconciliation correspond to an insertion.

update - the newly added cells, the update. This can be null out of convenience, in which case this function simply copy the cells from existing to writer.

deletion - the deletion time that applies to the cells being considered. This deletion time may delete cells in both existing and update.

builder - the row build to which the result of the reconciliation is written.

nowInSec - the current time in seconds (which plays a role during reconciliation because deleted cells always have precedence on timestamp equality and deciding if a cell is a live or not depends on the current time due to expiring cells).

Returns:

the smallest timestamp delta between corresponding cells from existing and update. A timestamp delta being computed as the difference between a cell from update and the cell in existing having the same cell path (if such cell exists). If the intersection of cells from existing and update having the same cell path is empty, this returns Long.MAX_VALUE.