PostgreSQL: manipulate binary data - change last byte with SQL command

Question

In a PostgreSQL table I have a column file_bytes which has the data type bytea.

I am looking for a simple SQL statement to manipulate only the last byte of the content of this column.

`set_byte()`? https://www.postgresql.org/docs/current/static/functions-binarystring.html — , Sep 28 '18 at 08:37

score 2 · Accepted Answer · answered Sep 28 '18 at 09:21

UPDATE test 
SET file_bytes = overlay(file_bytes placing 'X'::bytea from octet_length(file_bytes));

octet_length() gives the number of bytes of binary data. overlay() allows to rewrite data from a certain position.

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