Issues adding snippet in Wagtail with primary key longer than 50 characters

[pcraciunoiu]

Caught this error for a custom Snippet with this key:

class CustomSnippet(index.Indexed, Model):
    value = models.CharField(max_length=128, primary_key=True)

It happened during INSERT INTO wagtailsearch_indexentry

Exception raised while adding CustomSnippet() into the 'default' search backend
DataError: value too long for type character varying(50)

It seems that if a snippet has a PK longer than 50 characters, the IndexEntry insert fails, could we bump that to a higher number?

Not a blocker, it just seems a bit low.