Merge "Extract format_constraint truncation rules to ON CONFLICT"

2 files changed, 44 insertions, 15 deletions

diff --git a/lib/sqlalchemy/dialects/postgresql/base.py b/lib/sqlalchemy/dialects/postgresql/base.py
index 070490c1d..d8e4d5d20 100644
--- a/lib/sqlalchemy/dialects/postgresql/base.py
+++ b/lib/sqlalchemy/dialects/postgresql/base.py
@@ -2323,8 +2323,16 @@ class PGCompiler(compiler.SQLCompiler):
     def _on_conflict_target(self, clause, **kw):
 
         if clause.constraint_target is not None:
-            target_text = "ON CONSTRAINT %s" % self.preparer.quote(
-                clause.constraint_target
+            # target may be a name of an Index, UniqueConstraint or
+            # ExcludeConstraint.  While there is a separate
+            # "max_identifier_length" for indexes, PostgreSQL uses the same
+            # length for all objects so we can use
+            # truncate_and_render_constraint_name
+            target_text = (
+                "ON CONSTRAINT %s"
+                % self.preparer.truncate_and_render_constraint_name(
+                    clause.constraint_target
+                )
             )
         elif clause.inferred_target_elements is not None:
             target_text = "(%s)" % ", ".join(
diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 7007c2e86..581dad4fb 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -5057,20 +5057,41 @@ class IdentifierPreparer(object):
         else:
             name = constraint.name
 
+        if constraint.__visit_name__ == "index":
+            return self.truncate_and_render_index_name(
+                name, _alembic_quote=_alembic_quote
+            )
+        else:
+            return self.truncate_and_render_constraint_name(
+                name, _alembic_quote=_alembic_quote
+            )
+
+    def truncate_and_render_index_name(self, name, _alembic_quote=True):
+        # calculate these at format time so that ad-hoc changes
+        # to dialect.max_identifier_length etc. can be reflected
+        # as IdentifierPreparer is long lived
+        max_ = (
+            self.dialect.max_index_name_length
+            or self.dialect.max_identifier_length
+        )
+        return self._truncate_and_render_maxlen_name(
+            name, max_, _alembic_quote
+        )
+
+    def truncate_and_render_constraint_name(self, name, _alembic_quote=True):
+        # calculate these at format time so that ad-hoc changes
+        # to dialect.max_identifier_length etc. can be reflected
+        # as IdentifierPreparer is long lived
+        max_ = (
+            self.dialect.max_constraint_name_length
+            or self.dialect.max_identifier_length
+        )
+        return self._truncate_and_render_maxlen_name(
+            name, max_, _alembic_quote
+        )
+
+    def _truncate_and_render_maxlen_name(self, name, max_, _alembic_quote):
         if isinstance(name, elements._truncated_label):
-            # calculate these at format time so that ad-hoc changes
-            # to dialect.max_identifier_length etc. can be reflected
-            # as IdentifierPreparer is long lived
-            if constraint.__visit_name__ == "index":
-                max_ = (
-                    self.dialect.max_index_name_length
-                    or self.dialect.max_identifier_length
-                )
-            else:
-                max_ = (
-                    self.dialect.max_constraint_name_length
-                    or self.dialect.max_identifier_length
-                )
             if len(name) > max_:
                 name = name[0 : max_ - 8] + "_" + util.md5_hex(name)[-4:]
         else: