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How to Remap Array Values Of A Column In Postgresql?

2 minutes read

To remap array values of a column in PostgreSQL, you can use the ARRAY_AGG function combined with a CASE statement. This allows you to map your existing array values to new values based on certain conditions or criteria. For example, you can create a new column that contains the remapped array values by using a SELECT query with the ARRAY_AGG function and a CASE statement to define the mapping logic. This approach enables you to transform the values within the array column according to your specific requirements.


What function is used to change array values in PostgreSQL?

The function used to change array values in PostgreSQL is array_replace(). This function replaces all occurrences of a specified value in an array with a new value.


What is the best approach to remapping array values in PostgreSQL?

One approach to remapping array values in PostgreSQL is to use the unnest function along with a mapping table. Here is a step-by-step guide to achieve this:

  1. Create a mapping table that contains the original values and their corresponding remapped values. For example:
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CREATE TABLE remapping_table (
  original_value text,
  remapped_value text
);

INSERT INTO remapping_table VALUES ('A', 'X');
INSERT INTO remapping_table VALUES ('B', 'Y');
INSERT INTO remapping_table VALUES ('C', 'Z');


  1. Use the unnest function to expand the array values into individual rows, then join with the mapping table to get the remapped values. For example:
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SELECT array_agg(rt.remapped_value) as remapped_array
FROM my_table t
CROSS JOIN LATERAL unnest(t.array_column) val
JOIN remapping_table rt ON rt.original_value = val
GROUP BY t.id;


  1. In this example, my_table is the table containing the array column that needs to be remapped. Replace array_column with the name of your array column and id with the primary key of your table.
  2. This query will return a new array column remapped_array with the values remapped according to the mapping table.
  3. You can then update the original array column with the remapped values if necessary.


By following these steps, you can efficiently remap array values in PostgreSQL using a mapping table and the unnest function.


What is the impact of remapping array values on existing data in PostgreSQL?

Remapping array values in PostgreSQL does not directly impact the existing data in the array. The remapping operation creates a new array with the updated values, leaving the original array values unchanged. This means that any queries or operations on the existing data in the array will continue to return the original values.


If you want to update the existing array values in the database, you would need to explicitly update the array column using an UPDATE statement, rather than simply remapping the array values in memory.

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