Add table and crud

alembic/versions/ce116d0badc8_create_latest_s3_block_table.py

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+"""Create latest_s3_block table
+
+Revision ID: ce116d0badc8
+Revises: 5c5375de15fd
+Create Date: 2022-01-31 23:36:34.971594
+
+"""
+import sqlalchemy as sa
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = "ce116d0badc8"
+down_revision = "5c5375de15fd"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_table(
+        "latest_s3_block",
+        sa.Column("block_number", sa.Numeric, nullable=False),
+        sa.Column("updated_at", sa.TIMESTAMP, server_default=sa.func.now()),
+    )
+
+
+def downgrade():
+    op.drop_table("latest_s3_block")

mev_inspect/crud/latest_s3_block.py

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+from typing import Optional
+
+
+def find_latest_s3_block(db_session) -> Optional[int]:
+    result = db_session.execute(
+        "SELECT block_number FROM latest_s3_block LIMIT 1"
+    ).one_or_none()
+    if result is None:
+        return None
+    else:
+        return int(result[0])
+
+
+def update_latest_s3_block(db_session, block_number) -> None:
+    db_session.execute(
+        """
+            UPDATE latest_s3_block
+                SET block_number = :block_number, updated_at = current_timestamp;
+            INSERT INTO latest_s3_block
+                (block_number, updated_at)
+            SELECT :block_number, current_timestamp
+                WHERE NOT EXISTS (SELECT 1 FROM latest_s3_blocks);
+            """,
+        params={"block_number": block_number},
+    )