Column qualifiers are the column names, also known as column keys. For example, in Figure 5-1, Column A and Column B are the column qualifiers. A table value is stored at the intersection of a column and a row. A row is identified by a row key.

What is the HBase column qualifier?

Column qualifiers are the column names, also known as column keys. For example, in Figure 5-1, Column A and Column B are the column qualifiers. A table value is stored at the intersection of a column and a row. A row is identified by a row key.

What is HBase row key?

An HBase row consists of a row key and one or more column values. A row key is a unique identifier for the table row. An HBase table is a multi-dimensional map comprised of one or more columns and rows of data. You specify the complete set of column families when you create an HBase table.

What is HBase column family?

An HBase table contains column families , which are the logical and physical grouping of columns. There are column qualifiers inside of a column family, which are the columns. Column families contain columns with time stamped versions. Columns only exist when they are inserted, which makes HBase a sparse database.

Does HBase have primary key?

Primary key design In HBase, the only way to access a particular row is with the rowkey. In addition, data stored in an HBase table is sorted by the rowkey. Phoenix builds the rowkey value by concatenating the values of each of the columns in the row, in the order they’re defined in the primary key.

What is column family in BigTable?

Column families are defined when the table is first created. Within a column family, one may have one or more named columns. All data within a column family is usually of the same type. The implementation of BigTable usually compresses all the columns within a column family together.

What is a column qualifier in SQL?

A qualifier for a column name can be a table name, a view name, an alias name, a synonym, or a correlation name. Whether a column name can be qualified depends, like its meaning, on its context. In some forms of the COMMENT and LABEL statements, a column name must be qualified.

What are the key components of HBase?

HBase has three major components: the client library, a master server, and region servers.

Why is HBase column family?

Row—a collection of column families. Column Family—a collection of columns. HBase stores data by column family and not row. This makes for faster retrieval of columns since they are located near each other.

What of the following are key characteristics of a column family in Apache HBase?

Features of HBase

  • HBase is linearly scalable.
  • It has automatic failure support.
  • It provides consistent read and writes.
  • It integrates with Hadoop, both as a source and a destination.
  • It has easy java API for client.
  • It provides data replication across clusters.

What is a column in a table in HBase?

HBase is a column-oriented database and the tables in it are sorted by row. The table schema defines only column families, which are the key value pairs. A table have multiple column families and each column family can have any number of columns. Subsequent column values are stored contiguously on the disk.

What type of data is stored in HBase?

HBase internally uses Hash tables and provides random access, and it stores the data in indexed HDFS files for faster lookups. HBase is a column-oriented database and the tables in it are sorted by row. The table schema defines only column families, which are the key value pairs.

How do I set the Java_home variable in HBase?

You must set the JAVA_HOME environment variable before starting HBase. To make this easier, HBase lets you set it within the conf/hbase-env.sh file. You must locate where Java is installed on your machine, and one way to find this is by using the whereis java command.

How do I start HBase on an existing HDFS instance?

To home HBase on an existing instance of HDFS, set the hbase.rootdir to point at a directory up on your instance: e.g. hdfs://namenode.example.org:8020/hbase. For more on this variant, see the section below on Standalone HBase over HDFS. The bin/start-hbase.sh script is provided as a convenient way to start HBase.