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Alphanumeric Sorting in PostgreSQL

Alphanumeric sorting involves sorting alphanumeric values in a specific order. Today we are going to take a look at alphanumeric sorting in PostgreSQL.

By default, PostgreSQL relies on a lexicographic sorting order. In other words, alphanumeric values are sorted according to their ASCII/Unicode character codes.

However, alphanumeric sorting may not always produce the desired order for values that contain both letters and numbers.

We can easily set up alphanumeric sorting in PostgreSQL via different techniques depending on our specific requirements:

• Natural Sorting:

  This method involves ordering alphanumeric values in such a way that it respects the numerical order within the value.

  For instance, if we have values like “A1”, “A10”, and “A2”, natural sorting would order them as “A1”, “A2”, and “A10”.

  This is done via the natsort extension. It offers a natural sorting function for PostgreSQL. We have to install and enable this extension before we can use it in our queries.

  Let’s take a look at an example that uses the natsort extension for alphanumeric sorting:

  -- Install the natsort extension
CREATE EXTENSION IF NOT EXISTS natsort;
-- Use the natsort function for alphanumeric sorting
SELECT column_name FROM table_name ORDER BY natsort(column_name);

• Custom Sorting

  We can use custom sorting if natural sorting is not suitable in a particular scenario.

  We can define a custom sorting order using the ORDER BY clause in our SQL query.

  When we assign weights to different characters or character sets, we can create a custom sorting order that suits our needs.

  For instance, you can choose to prioritize digits or specific letters over others.

  For example:
  SELECT column_name
FROM table_name
ORDER BY
CASE
WHEN column_name ~ '^\d' THEN 0 -- Numbers first
WHEN column_name ~ '^\D' THEN 1 -- Letters next
END,
column_name;

  Here, the query uses a CASE statement to assign a weight of 0 for values starting with a digit (\d), and a weight of 1 for values starting with a non-digit (\D). Furthermore, the ORDER BY clause then sorts the values based on this custom weighting.

At the end of the day, we can achieve alphanumeric sorting in PostgreSQL via natsort extension or by implementing custom sorting logic using the ORDER BY clause.

The approach we choose depends on the specific requirements of our application and the desired sorting order for our alphanumeric values.

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Conclusion

To conclude, our Support Techs demonstrated how to set up alphanumeric sorting in PostgreSQL.