Error 42703 when using aws_s3.table_import_from_s3 to import CSV data into Redshift

I apologize, but there seems to be a misunderstanding in your approach. The aws_s3.table_import_from_s3 function is not a feature of Amazon Redshift, but rather a function used with Amazon RDS for PostgreSQL. For importing data from S3 into Redshift, you should use the COPY command, which is specifically designed for this purpose and offers better performance for large-scale data imports.

To achieve your requirements efficiently in Redshift, you can use the COPY command with a few modifications:

1. Create a temporary staging table with the same structure as your CSV file (5 columns).
2. Use the COPY command to load data from S3 into this staging table.
3. Insert data from the staging table into your final table, adding the static value for the 6th column.

Here's an example of how you could do this:

-- Create a temporary staging table
CREATE TEMPORARY TABLE temp_my_table (
    col1 datatype,
    col2 datatype,
    col3 datatype,
    col4 datatype,
    col5 datatype
);

-- Copy data from S3 into the staging table
COPY temp_my_table (col1, col2, col3, col4, col5)
FROM 's3://my-s3-bucket/path/to/my-file.csv'
IAM_ROLE 'arn:aws:iam::0123456789012:role/MyRedshiftRole'
FORMAT CSV
HEADER;

-- Insert data from staging table to final table, adding the static value
INSERT INTO my_table (col1, col2, col3, col4, col5, created_by)
SELECT col1, col2, col3, col4, col5, 'DUMMY'
FROM temp_my_table;

This approach meets your requirements:

1. It doesn't use an intermediary permanent table or require UPDATE or ALTER commands.
2. The COPY command is highly efficient for loading large amounts of data (300 million rows).
3. It adds the static 'DUMMY' value for the created_by column during the insert.

The COPY command in Redshift is already optimized for user-friendliness and performance when importing large datasets from S3. It supports various file formats, compression, and parallel processing, making it well-suited for your use case.
Sources
Tutorial: Loading data from Amazon S3 - Amazon Redshift
Loading data in Amazon Redshift - Amazon Redshift
Importing data from Amazon S3 to your RDS for PostgreSQL DB instance - Amazon Relational Database Service