The HBase command for Hadoop

The HBase command for Hadoop

HBase Basics *
The construction of the HBase cluster *
HBASE shell***
Bulk Import of hbase * * *
Java Client for HBase * * *
Table Design for HBase *
The underlying storage model for HBase *
HBase optimization *
HBase co-processor *

1.Hbase Introduction

Hbase–hadoop Database is a highly reliable, high-performance, column-oriented, scalable distributed storage system that leverages HBase technology to build large-scale structured storage clusters on inexpensive PC servers.

HBase uses Hadoop HDFs as its file storage system, using Hadoop mapreduce to process massive amounts of data in HBase, using zookeeper as a coordination tool.

Distributed open source database, based on Hadoop Distributed File System (HDFS)

Imitation provides all the functions of the BigTable database of the Google file system

Handle a very large table

Ordinary computer processing 1 billion data

Using MapReduce to calculate data, using zookeeper to coordinate resources

2. Overview of the column database

A column database, which differs from the row database in terms of data storage, and all data is accessed by column.

Row database when doing some column analysis, all column information must be read out

While the column database is accessed by columns, it is possible to perform queries and analysis with only a specific column of I/O, saving 90% efficiency.

In addition, the column-based database has a dedicated column compression algorithm on each column to further improve database performance, which is not available in a row database.

3.Hbase Data Model-logical model

Tables (table) string
Row rows are uniquely identified by the row health (Rowkey)
Columns family (column failmy) row data grouped by column family CF, when creating a table is defined, not easily modified
Data positioning within column qualifier (column qualifier) column by column qualifier
Unit (cell) row Health, column family and column qualifier to determine a unit, value
The time version (vesion) cell value is sometimes versioned, with a timestamp to identify the default of 3.

1) Row key (RowKey)
A row key is a byte array, and any string can be used as a row key;
The rows in the table are sorted according to the row key, and the data is sorted by the byte order of row key (byte order) stored
All access to the table is through the row key
(Single Rowkey access, or Rowkey range access, or full table scan)

2) The column family (columnfamily) CF must be given when the table is defined
Data is stored separately by CF, and HBase's so-called Columnstore is stored separately based on CF
(Each CF corresponds to a store), this design is ideal for data analysis scenarios

3) row qualifier (column qualifier)
The data in the column is positioned through the column qualifier each CF can have one or more column members (Columnqualifier),
Column members do not need to be given when the table is defined, new column family members can then be added on demand, dynamically
4) timestamp (TimeStamp)
Each cell may have multiple versions, which are distinguished by timestamps

5) Cell Value
Cell is determined by row key, column family: qualifier, timestamp only
There is no type of data in the cell, all stored in bytecode form

4. HBase Data Model-Physical model

The physical data model is essentially the partitioning of a row in a logical model into a physical model stored according to column family.

For bigtable data Model operations, the row is locked and the row's atomic operation is guaranteed.

HBase consists of rows and columns divided by ((column family))

Each column family on the hard disk has its own hfile (binary file, cannot be read directly)

hfile: A column family can have more than one hfile, but a hfile cannot store multiple column families (column), and each column family has a memstore

A column family of data in a row does not necessarily reside in the same hfile, and the column family data in one row needs to be physically stored together

The HBase table is divided horizontally into a number of region

Region is stored in a different region server.

5.

The HBase command for Hadoop