Constraints (Apache HBase 1.1.7 API)

java.lang.Object
- org.apache.hadoop.hbase.constraint.Constraints

```
@InterfaceAudience.Private
public final class Constraints
extends Object
```
Utilities for adding/removing constraints from a table.
Constraints can be added on table load time, via the HTableDescriptor.
NOTE: this class is NOT thread safe. Concurrent setting/enabling/disabling of constraints can cause constraints to be run at incorrect times or not at all.

Method Summary

Methods
Modifier and Type	Method and Description
`static void`	`add(HTableDescriptor desc, Class<? extends Constraint>... constraints)` Add configuration-less constraints to the table.
`static void`	`add(HTableDescriptor desc, Class<? extends Constraint> constraint, org.apache.hadoop.conf.Configuration conf)` Add a `Constraint` to the table with the given configuration
`static void`	`add(HTableDescriptor desc, Pair<Class<? extends Constraint>,org.apache.hadoop.conf.Configuration>... constraints)` Add constraints and their associated configurations to the table.
`static void`	`disable(HTableDescriptor desc)` Turn off processing constraints for a given table, even if constraints have been turned on or added.
`static void`	`disableConstraint(HTableDescriptor desc, Class<? extends Constraint> clazz)` Disable the given `Constraint`.
`static void`	`enable(HTableDescriptor desc)` Enable constraints on a table.
`static void`	`enableConstraint(HTableDescriptor desc, Class<? extends Constraint> clazz)` Enable the given `Constraint`.
`static boolean`	`enabled(HTableDescriptor desc, Class<? extends Constraint> clazz)` Check to see if the given constraint is enabled.
`static boolean`	`has(HTableDescriptor desc, Class<? extends Constraint> clazz)` Check to see if the Constraint is currently set.
`static void`	`remove(HTableDescriptor desc)` Remove all `Constraints` that have been added to the table and turn off the constraint processing.
`static void`	`remove(HTableDescriptor desc, Class<? extends Constraint> clazz)` Remove the constraint (and associated information) for the table descriptor.
`static void`	`setConfiguration(HTableDescriptor desc, Class<? extends Constraint> clazz, org.apache.hadoop.conf.Configuration configuration)` Update the configuration for the `Constraint`; does not change the order in which the constraint is run.

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

- Method Detail
  - enable
```
public static void enable(HTableDescriptor desc)
                   throws IOException
```
    Enable constraints on a table.
    Currently, if you attempt to add a constraint to the table, then Constraints will automatically be turned on.
    
    Parameters:
    desc - table description to add the processor
    
    Throws:
    
    IOException - If the ConstraintProcessor CP couldn't be added to the table.
  - disable
```
public static void disable(HTableDescriptor desc)
```
    Turn off processing constraints for a given table, even if constraints have been turned on or added.
    
    Parameters:
    desc - HTableDescriptor where to disable Constraints.
  - remove
```
public static void remove(HTableDescriptor desc)
```
    Remove all Constraints that have been added to the table and turn off the constraint processing.
    All Configurations and their associated Constraint are removed.
    
    Parameters:
    desc - HTableDescriptor to remove Constraints from.
  - has
```
public static boolean has(HTableDescriptor desc,
          Class<? extends Constraint> clazz)
```
    Check to see if the Constraint is currently set.
    
    Parameters:
    desc - HTableDescriptor to check
    clazz - Constraint class to check for.
    
    Returns:
    true if the Constraint is present, even if it is disabled. false otherwise.
  - add
```
public static void add(HTableDescriptor desc,
       Class<? extends Constraint>... constraints)
                throws IOException
```
    Add configuration-less constraints to the table.
    This will overwrite any configuration associated with the previous constraint of the same class.
    Each constraint, when added to the table, will have a specific priority, dictating the order in which the Constraint will be run. A Constraint earlier in the list will be run before those later in the list. The same logic applies between two Constraints over time (earlier added is run first on the regionserver).
    
    Parameters:
    desc - HTableDescriptor to add Constraints
    constraints - Constraints to add. All constraints are considered automatically enabled on add
    
    Throws:
    
    IOException - If constraint could not be serialized/added to table
  - add
```
public static void add(HTableDescriptor desc,
       Pair<Class<? extends Constraint>,org.apache.hadoop.conf.Configuration>... constraints)
                throws IOException
```
    Add constraints and their associated configurations to the table.
    Adding the same constraint class twice will overwrite the first constraint's configuration
    Each constraint, when added to the table, will have a specific priority, dictating the order in which the Constraint will be run. A Constraint earlier in the list will be run before those later in the list. The same logic applies between two Constraints over time (earlier added is run first on the regionserver).
    
    Parameters:
    desc - HTableDescriptor to add a Constraint
    constraints - Pair of a Constraint and its associated Configuration. The Constraint will be configured on load with the specified configuration.All constraints are considered automatically enabled on add
    
    Throws:
    
    IOException - if any constraint could not be deserialized. Assumes if 1 constraint is not loaded properly, something has gone terribly wrong and that all constraints need to be enforced.
  - add
```
public static void add(HTableDescriptor desc,
       Class<? extends Constraint> constraint,
       org.apache.hadoop.conf.Configuration conf)
                throws IOException
```
    Add a Constraint to the table with the given configuration
    Each constraint, when added to the table, will have a specific priority, dictating the order in which the Constraint will be run. A Constraint added will run on the regionserver before those added to the HTableDescriptor later.
    
    Parameters:
    desc - table descriptor to the constraint to
    constraint - to be added
    conf - configuration associated with the constraint
    
    Throws:
    
    IOException - if any constraint could not be deserialized. Assumes if 1 constraint is not loaded properly, something has gone terribly wrong and that all constraints need to be enforced.
  - setConfiguration
```
public static void setConfiguration(HTableDescriptor desc,
                    Class<? extends Constraint> clazz,
                    org.apache.hadoop.conf.Configuration configuration)
                             throws IOException,
                                    IllegalArgumentException
```
    Update the configuration for the Constraint; does not change the order in which the constraint is run.
    
    Parameters:
    desc - HTableDescriptor to update
    clazz - Constraint to update
    configuration - to update the Constraint with.
    
    Throws:
    
    IOException - if the Constraint was not stored correctly
    
    IllegalArgumentException - if the Constraint was not present on this table.
  - remove
```
public static void remove(HTableDescriptor desc,
          Class<? extends Constraint> clazz)
```
    Remove the constraint (and associated information) for the table descriptor.
    
    Parameters:
    desc - HTableDescriptor to modify
    clazz - Constraint class to remove
  - enableConstraint
```
public static void enableConstraint(HTableDescriptor desc,
                    Class<? extends Constraint> clazz)
                             throws IOException
```
    Enable the given Constraint. Retains all the information (e.g. Configuration) for the Constraint, but makes sure that it gets loaded on the table.
    
    Parameters:
    desc - HTableDescriptor to modify
    clazz - Constraint to enable
    
    Throws:
    
    IOException - If the constraint cannot be properly deserialized
  - disableConstraint
```
public static void disableConstraint(HTableDescriptor desc,
                     Class<? extends Constraint> clazz)
                              throws IOException
```
    Disable the given Constraint. Retains all the information (e.g. Configuration) for the Constraint, but it just doesn't load the Constraint on the table.
    
    Parameters:
    desc - HTableDescriptor to modify
    clazz - Constraint to disable.
    
    Throws:
    
    IOException - if the constraint cannot be found
  - enabled
```
public static boolean enabled(HTableDescriptor desc,
              Class<? extends Constraint> clazz)
                       throws IOException
```
    Check to see if the given constraint is enabled.
    
    Parameters:
    desc - HTableDescriptor to check.
    clazz - Constraint to check for
    
    Returns:
    true if the Constraint is present and enabled. false otherwise.
    
    Throws:
    
    IOException - If the constraint has improperly stored in the table

Class Constraints

Method Summary

Methods inherited from class java.lang.Object

Method Detail

enable

disable

remove

has

add

add

add

setConfiguration

remove

enableConstraint

disableConstraint

enabled