ShardBoundaries (apache-cassandra API)

java.lang.Object
- org.apache.cassandra.db.memtable.ShardBoundaries

```
public class ShardBoundaries
extends java.lang.Object
```
Holds boundaries (tokens) used to map a particular token (so partition key) to a shard id. In practice, each keyspace has its associated boundaries, see Keyspace.
Technically, if we use n shards, this is a list of n-1 tokens and each token tk gets assigned to the shard ID corresponding to the slot of the smallest token in the list that is greater to tk, or n if tk is bigger than any token in the list.

Field Summary

Fields
Modifier and Type Field Description

static ShardBoundaries NONE

long ringVersion

Constructor Summary

Constructors
Constructor	Description
`ShardBoundaries(java.util.List<Token> boundaries, long ringVersion)`
`ShardBoundaries(Token[] boundaries, long ringVersion)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`equals(java.lang.Object o)`
`int`	`getShardForKey(PartitionPosition key)`	Computes the shard to use for the provided key.
`int`	`getShardForToken(Token tk)`	Computes the shard to use for the provided token.
`int`	`hashCode()`
`int`	`shardCount()`	The number of shards that this boundaries support, that is how many different shard ids `getShardForToken(org.apache.cassandra.dht.Token)` might possibly return.
`java.lang.String`	`toString()`

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

- Field Detail
  - NONE
```
public static final ShardBoundaries NONE
```
  - ringVersion
```
public final long ringVersion
```
- Constructor Detail
  - ShardBoundaries
```
public ShardBoundaries(Token[] boundaries,
                       long ringVersion)
```
  - ShardBoundaries
```
public ShardBoundaries(java.util.List<Token> boundaries,
                       long ringVersion)
```
- Method Detail
  - getShardForToken
```
public int getShardForToken(Token tk)
```
    Computes the shard to use for the provided token.
  - getShardForKey
```
public int getShardForKey(PartitionPosition key)
```
    Computes the shard to use for the provided key.
  - shardCount
```
public int shardCount()
```
    The number of shards that this boundaries support, that is how many different shard ids getShardForToken(org.apache.cassandra.dht.Token) might possibly return.
    
    Returns:
    
    the number of shards supported by theses boundaries.
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - equals
```
public boolean equals(java.lang.Object o)
```
    Overrides:
    
    equals in class java.lang.Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class java.lang.Object