com.h3c.util.persistence.cassandra.index

Interface Denormalizer<C extends Serializable & Comparable<C>,D>

Type Parameters:

C - type of the row key in the main column family. Such row key will be the column name in the secondary index column.

D - type of the denormalized data. Data to set as the value in the indexed columns.

public interface Denormalizer<C extends Serializable & Comparable<C>,D>

Secondary index denormalizer.

When a column family is created to keep custom secondary indexes, the row key in such column family would typically be a value of the indexed column and the column names would be the row keys in the main column family that has such value set. Denormalizer is used to include more data in the secondary index column family so it is available in a single read.

Examples:

 column_family_secondary_index {
     "indexed_value_1": {
         id_i: <data provided by the denormalizer>,
         ...
         id_j: <data provided by the denormalizer>,
     }
     "indexed_value_2": {
         id_m: <data provided by the denormalizer>,
         ...
         id_n: <data provided by the denormalizer>,
     }
 }
 
 column_family_persons_by_status {
     "Single": {
         person_id_i: <Name, Last Name>,
         ...
         person_id_j: <Name, Last Name>,
     }
     "Married": {
         person_id_m: <Name, Last Name>,
         ...
         person_id_n: <Name, Last Name>,
     }
 }
 

If the columns need to be sorted by a different attribute the attribute is included as part of the column name (composite column name). This does not affect the denormalizer.

Example:

 column_family_persons_by_status_sorted_by_last_name_and_name {
     "Single": {
         <last_name_i, name_i, person_id_i>: <Birthdate_i>,
         ...
         <last_name_j, name_j, person_id_j>: <Birthdate_j>,
     }
     "Married": {
         <last_name_m, name_m, person_id_m>: <Birthdate_m>,
         ...
         <last_name_n, name_n, person_id_n>: <Birthdate_n>,
     }
 }
 

Method Summary

Methods

Modifier and Type	Method and Description
Column<C,D>	getColumn(ColumnName<C,D> name, D value) Creates an indexed column with denormalized data.
ColumnDecoder<C,D>	getColumnDecoder() Gets the column decoder.

Method Detail

getColumn

Column<C,D> getColumn(ColumnName<C,D> name,
                    D value)

Creates an indexed column with denormalized data.

Parameters:

name - indexed column name.

value - denormalized data.

Returns:

an indexed column.

getColumnDecoder

ColumnDecoder<C,D> getColumnDecoder()

Gets the column decoder.

Returns:

the column decoder.