diff --git a/tansu/alembic/versions/2024_08_09-fcd0be8495da_unique_constraints.py b/tansu/alembic/versions/2024_08_09-fcd0be8495da_unique_constraints.py
new file mode 100644
index 0000000..95ab3df
--- /dev/null
+++ b/tansu/alembic/versions/2024_08_09-fcd0be8495da_unique_constraints.py
@@ -0,0 +1,31 @@
+"""Unique constraints
+
+Revision ID: fcd0be8495da
+Revises: 1f84e2b6843a
+Create Date: 2024-08-09 19:34:02.104464+00:00
+
+"""
+
+from typing import Sequence, Union
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "fcd0be8495da"
+down_revision: Union[str, None] = "1f84e2b6843a"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_unique_constraint(
+        "_action_project_key_value", "event", ["action", "project_key", "value"]
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_constraint("_action_project_key_value", "event", type_="unique")
+    # ### end Alembic commands ###
diff --git a/tansu/soroban_versioning_events.py b/tansu/soroban_versioning_events.py
index f197573..467dbac 100644
--- a/tansu/soroban_versioning_events.py
+++ b/tansu/soroban_versioning_events.py
@@ -2,7 +2,7 @@
 
 from tansu.events.ingest import events_to_db, fetch_events
 
-contract_id = "CC3JCYWHNMPMQTOQUNDCJSCFSWRFZIE2JVSAUEXEG56DMKOMI3RL7VOH"
+contract_id = "CAP52ERGUZ65UNPHP36CQBHYUPEUG2TT4NPVEV7CREWRT7UCPD7PRWEE"
 start_ledger = None
 
 events, _ = fetch_events(contract_id=contract_id, start_ledger=start_ledger)
diff --git a/tansu/src/tansu/events/database/db_models.py b/tansu/src/tansu/events/database/db_models.py
index 24eb570..d48e400 100644
--- a/tansu/src/tansu/events/database/db_models.py
+++ b/tansu/src/tansu/events/database/db_models.py
@@ -1,4 +1,4 @@
-from sqlalchemy import orm
+from sqlalchemy import orm, UniqueConstraint
 
 from tansu.events.database.session_factory import SqlAlchemyBase
 
@@ -12,6 +12,12 @@ class Event(SqlAlchemyBase):
     project_key: orm.Mapped[str] = orm.mapped_column(index=True)
     value: orm.Mapped[str]
 
+    __table_args__ = (
+        UniqueConstraint(
+            "action", "project_key", "value", name="_action_project_key_value"
+        ),
+    )
+
 
 class LatestLedger(SqlAlchemyBase):
     __tablename__ = "latest_ledger"