Add table to track the most recently updated block

alembic/versions/a02f3f2c469f_create_latest_block_table.py

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+"""Create latest block table
+
+Revision ID: a02f3f2c469f
+Revises: d70c08b4db6f
+Create Date: 2021-09-13 21:32:27.181344
+
+"""
+import sqlalchemy as sa
+from alembic import op
+
+
+# revision identifiers, used by Alembic.
+revision = "a02f3f2c469f"
+down_revision = "d70c08b4db6f"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_table(
+        "latest_block_update",
+        sa.Column("block_number", sa.Numeric, primary_key=True),
+        sa.Column("updated_at", sa.TIMESTAMP, server_default=sa.func.now()),
+    )
+
+
+def downgrade():
+    op.drop_table("latest_block_update")

mev_inspect/crud/latest_block_update.py

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+from typing import Optional
+
+
+def find_latest_block_update(db_session) -> Optional[int]:
+    result = db_session.execute(
+        "SELECT block_number FROM latest_block_update LIMIT 1"
+    ).one_or_none()
+    if result is None:
+        return None
+    else:
+        return int(result[0])
+
+
+def update_latest_block(db_session, block_number) -> None:
+    db_session.execute(
+        """
+            UPDATE latest_block_update
+                SET block_number = :block_number, updated_at = current_timestamp;
+            INSERT INTO latest_block_update
+                (block_number, updated_at)
+            SELECT :block_number, current_timestamp
+                WHERE NOT EXISTS (SELECT 1 FROM latest_block_update);
+            """,
+        params={"block_number": block_number},
+    )