How to diagnose and fix the 54011 too_many_columns error code in Postgres.

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The 54011 too_many_columns error in PostgreSQL occurs when a table is defined with or is being altered to have more columns than PostgreSQL allows. The exact limit can depend on the version of PostgreSQL you are using, but traditionally, the limit has been around 1600 columns per table. To diagnose and fix this error, you can consider the following strategies:

Check the Number of Columns

If you encounter this error when creating or altering a table, count the number of columns you are trying to create. For example:

CREATE TABLE my_table (
    col1 TYPE,
    col2 TYPE,
    ...
    colN TYPE
);

If N exceeds the maximum allowed number of columns, you will see the 54011 too_many_columns error.

Normalize Your Database

If you are hitting the column limit, it may be a sign that your table is not properly normalized. Consider breaking the table into multiple related tables to reduce the number of columns. For example:

-- Instead of this:
CREATE TABLE person (
    person_id INT,
    name TEXT,
    address_line1 TEXT,
    address_line2 TEXT,
    ...
    phone_number10 TEXT
);

-- Use something like this:
CREATE TABLE person (
    person_id INT,
    name TEXT
);

CREATE TABLE address (
    address_id INT,
    person_id INT REFERENCES person(person_id),
    address_line1 TEXT,
    address_line2 TEXT
    ...
);

CREATE TABLE phone_number (
    number_id INT,
    person_id INT REFERENCES person(person_id),
    phone_number TEXT
);

Use JSON or JSONB

If normalizing the database is not an option and you have a lot of semi-structured data, consider using a JSON or JSONB column to store multiple pieces of information in a single column:

CREATE TABLE person (
    person_id INT,
    name TEXT,
    contact_info JSONB
);

You can then store address, phone numbers, and other information in the contact_info JSONB column.

Use Arrays

For data that is of the same type and related (such as phone numbers or email addresses), you can use array data types:

CREATE TABLE person (
    person_id INT,
    name TEXT,
    phone_numbers TEXT[]
);

This allows you to store multiple phone numbers in a single column.

Evaluate the Design

If you are trying to create a table with many columns for a legitimate reason, and normalization is not suitable for your use case, you may need to re-evaluate the overall design of your database. It might be necessary to consider a different database system that does not have the same column limitations or to use a NoSQL database for more flexibility with schema design.

Check for Accidental Column Duplicates

Ensure that you are not accidentally adding duplicate columns or that a script isn’t erroneously trying to add multiple columns with the same name or similar patterns.

By carefully considering the design of your database and the structure of your tables, you should be able to work around the 54011 too_many_columns error in PostgreSQL. Keep in mind that hitting the column limit is often a sign of a design that could be improved for better performance and manageability. For more information on limits in PostgreSQL, you can refer to PostgreSQL Error Codes documentation or PostgreSQL’s official documentation on limits.

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