title: Large PostgreSQL table: better to add a column or create a new table to store metadata?
body: <p>I have a large table (~2 million rows), each row of which represents one image. I want to store the EXIF metadata in JSON format for each image. This JSON blob is about 6KB per image.</p>
  
  <p>This EXIF metadata won't be queried/used very often, and I'm wondering whether it'd be significantly more efficient to store it in a separate table with two columns (imageid, exifjson), or whether PostgreSQL will deal with this just fine as a <code>text</code> column on existing table. I wouldn't want adding the column to significantly slow down ordinary queries on the table, or the millions of 6KB text values to bog PostgreSQL down.</p>