How to use the command 'cbt' (with examples)

The ‘cbt’ command is a utility for reading data from Google Cloud’s Bigtable. It provides various functionalities to interact with Bigtable tables, such as listing tables, counting rows, looking up specific rows, searching rows based on regex pattern, and reading specific ranges of rows. This article will provide examples for each of these use cases.

Use case 1: List tables in the current project

Code:

cbt ls

Motivation:

• The motivation for using this example is to quickly get a list of tables available in the current project. It can be useful for understanding the structure and content of the Bigtable instance.

Explanation:

• The ’ls’ command is used to list the tables in the current project.

Example output:

table1
table2
table3
...

Use case 2: Print count of rows in a specific table in the current project

Code:

cbt count "table_name"

Motivation:

• This example is useful when you want to know the total number of rows in a specific table. It can help in understanding the size and volume of data within a table.

Explanation:

• The ‘count’ command is used to print the count of rows in a specific table.
• Replace “table_name” with the actual name of the table.

Example output:

Total rows in table_name: 1000

Use case 3: Display a single row from a specific table with only 1 (most recent) cell revision per column in the current project

Code:

cbt lookup "table_name" "row_key" cells-per-column=1

Motivation:

• This example is helpful when you want to retrieve a single row from a specific table. By specifying ‘cells-per-column=1’, it ensures that only the most recent cell revision per column is displayed.

Explanation:

• The ’lookup’ command is used to display a single row from a specific table.
• Replace “table_name” with the actual name of the table.
• Replace “row_key” with the key of the row to be looked up.
• The ‘cells-per-column’ argument is used to specify the number of most recent cell revisions per column to display.

Example output:

Column Family: family1
Qualifier: qualifier1
Value: value1
Timestamp: 2021-01-01 12:00:00

Column Family: family2
Qualifier: qualifier2
Value: value2
Timestamp: 2021-01-01 12:01:00

Use case 4: Display a single row with only specific column(s) (omit qualifier to return entire family) in the current project

Code:

cbt lookup "table_name" "row_key" columns="family1:qualifier1,family2:qualifier2,..."

Motivation:

• This example is useful when you only need to retrieve specific columns from a row instead of the entire row. Specifying the desired columns can save network bandwidth and processing time.

Explanation:

• The ’lookup’ command is used to display a single row from a specific table.
• Replace “table_name” with the actual name of the table.
• Replace “row_key” with the key of the row to be looked up.
• The ‘columns’ argument is used to specify the columns to be retrieved. Separate multiple columns with commas. Omit the qualifier to return the entire family.

Example output:

Column Family: family1
Qualifier: qualifier1
Value: value1
Timestamp: 2021-01-01 12:00:00

Column Family: family2
Qualifier: qualifier2
Value: value2
Timestamp: 2021-01-01 12:01:00

Use case 5: Search up to 5 rows in the current project by a specific regex pattern and print them

Code:

cbt read "table_name" regex="row_key_pattern" count=5

Motivation:

• This example is helpful when you want to search for rows in a table that match a specific regex pattern. It allows you to retrieve a limited number of rows (up to 5 in this case) that satisfy the pattern.

Explanation:

• The ‘read’ command is used to search for rows in a specific table based on a regex pattern.
• Replace “table_name” with the actual name of the table.
• Replace “row_key_pattern” with the desired regex pattern.
• The ‘regex’ argument is used to specify the regex pattern.
• The ‘count’ argument is used to limit the number of rows returned.

Example output:

Row key: row_key1
Column Family: family1
Qualifier: qualifier1
Value: value1

Row key: row_key2
Column Family: family1
Qualifier: qualifier1
Value: value1

Row key: row_key3
Column Family: family1
Qualifier: qualifier1
Value: value1

Use case 6: Read a specific range of rows and print only returned row keys in the current project

Code:

cbt read table_name start=start_row_key end=end_row_key keys-only=true

Motivation:

• This example is useful when you want to read a specific range of rows in a table and only need the row keys. It can be faster and more efficient if you don’t need the entire row data.

Explanation:

• The ‘read’ command is used to read a specific range of rows in a table.
• Replace “table_name” with the actual name of the table.
• Replace “start_row_key” with the starting key of the range.
• Replace “end_row_key” with the ending key of the range.
• The ‘keys-only’ argument is used to specify that only row keys should be printed.

Example output:

Row key: row_key1
Row key: row_key2
Row key: row_key3
...

Conclusion:

The ‘cbt’ command is a versatile utility for interacting with Google Cloud’s Bigtable. It provides a range of functionality for working with tables, such as listing tables, counting rows, looking up specific rows, searching rows by regex pattern, and reading specific ranges of rows. These examples demonstrate some common use cases and showcase the power and flexibility of the ‘cbt’ command.