ADT identifiers can be truncated

[tomsmalley]

Using deeply nested ADTs or types with long names can cause postgres to truncate them, emitting warnings like:

NOTICE: identifier "SomeReallyLongIdentifier/etc" will be truncated to "SomeReallyLongIden"

The truncation length is adjustable, defaulting to 63 bytes, and described here https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS.

Relevant example in the rel8 docs: https://hackage.haskell.org/package/rel8-1.6.0.0/docs/Rel8.html#g:19

Ideally this wouldn't happen (rel8 avoids generating very long identifiers) but at least it should be called out in the docs.

[jy14898]

It seems the latest version of rel8 is doing truncation itself (so the warning is silenced):

rel8/src/Rel8/Statement.hs

Line 199 in 688044a

pure $ take (63 - length suffix) label ++ suffix

But it still seems likely that field names collide. A simple 'fix' would be to make it so the suffix is a prefix, as that's the freshly generated unique name? parsed the expression wrong, this indeed fixes the issue!

[TeofilC]

A documentation PR would be appreciated if someone has capacity