From cd494a6ccd910641752365c48c45ae83b6afde5e Mon Sep 17 00:00:00 2001
From: Pekka Enberg <penberg@iki.fi>
Date: Mon, 21 Jul 2025 13:43:07 +0300
Subject: [PATCH] antithesis: Add `ALTER TABLE` parallel driver

---
 .../parallel_driver_alter_table.py            | 139 ++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100755 antithesis-tests/stress-composer/parallel_driver_alter_table.py

diff --git a/antithesis-tests/stress-composer/parallel_driver_alter_table.py b/antithesis-tests/stress-composer/parallel_driver_alter_table.py
new file mode 100755
index 000000000..82afd351b
--- /dev/null
+++ b/antithesis-tests/stress-composer/parallel_driver_alter_table.py
@@ -0,0 +1,139 @@
+#!/usr/bin/env -S python3 -u
+
+import json
+
+import turso
+from antithesis.random import get_random, random_choice
+
+# Get initial state
+try:
+    con_init = turso.connect("init_state.db")
+except Exception as e:
+    print(f"Error connecting to database: {e}")
+    exit(0)
+
+cur_init = con_init.cursor()
+
+# Get all existing tables from schemas
+existing_schemas = cur_init.execute("SELECT tbl, schema FROM schemas").fetchall()
+if not existing_schemas:
+    print("No tables found in schemas")
+    exit(0)
+
+# Select a random table
+selected_idx = get_random() % len(existing_schemas)
+selected_tbl, schema_json = existing_schemas[selected_idx]
+tbl_schema = json.loads(schema_json)
+
+print(f"Selected table: tbl_{selected_tbl} with {tbl_schema['colCount']} columns")
+
+# Connect to the main database
+try:
+    con = turso.connect("stress_composer.db", experimental_indexes=True)
+except Exception as e:
+    print(f"Failed to open stress_composer.db. Exiting... {e}")
+    exit(0)
+
+cur = con.cursor()
+
+# Define possible data types and constraints for new columns
+data_types = ["INTEGER", "REAL", "TEXT", "BLOB", "NUMERIC"]
+# When adding columns to existing tables, NOT NULL without DEFAULT is not allowed
+constraints = ["", "DEFAULT 0", "DEFAULT ''", "DEFAULT NULL"]
+
+# Choose ALTER TABLE operation
+# Weight ADD_COLUMN more heavily (60% chance)
+rand_val = get_random() % 100
+if rand_val < 60:
+    operation = "ADD_COLUMN"
+elif rand_val < 80:
+    operation = "RENAME_TABLE"
+else:
+    operation = "RENAME_COLUMN"
+
+try:
+    if operation == "ADD_COLUMN":
+        # Add a new column
+        new_col_num = tbl_schema["colCount"]
+        new_col_name = f"col_{new_col_num}"
+
+        # Choose data type and constraint
+        col_data_type = random_choice(data_types)
+        col_constraint = random_choice(constraints)
+
+        alter_stmt = f"ALTER TABLE tbl_{selected_tbl} ADD COLUMN {new_col_name} {col_data_type}"
+        if col_constraint:
+            alter_stmt += f" {col_constraint}"
+
+        print(f"Adding column: {alter_stmt}")
+        cur.execute(alter_stmt)
+
+        # Update schema in init_state.db
+        tbl_schema["colCount"] += 1
+        tbl_schema[new_col_name] = {
+            "data_type": col_data_type,
+            "constraint1": col_constraint,
+            "constraint2": ""
+        }
+
+        cur_init.execute(
+            "UPDATE schemas SET schema = ? WHERE tbl = ?",
+            (json.dumps(tbl_schema), selected_tbl)
+        )
+        print(f"Successfully added column {new_col_name} to tbl_{selected_tbl}")
+
+    elif operation == "RENAME_TABLE":
+        new_table = len(existing_schemas) + 1
+
+        alter_stmt = f"ALTER TABLE tbl_{selected_tbl} RENAME TO tbl_{new_table}"
+        print(f"Renaming table: {alter_stmt}")
+        cur.execute(alter_stmt)
+
+        # Update schemas table - change the tbl identifier to match the new name
+        # Extract the new table number/identifier from the new name
+        cur_init.execute(
+            "UPDATE schemas SET tbl = ? WHERE tbl = ?",
+            (new_table, selected_tbl)
+        )
+
+        print(f"Successfully renamed table tbl_{selected_tbl} to tbl_{new_table}")
+
+    elif operation == "RENAME_COLUMN":
+        # Select a random non-primary key column to rename
+        available_cols = []
+        pk_col = tbl_schema.get("pk", 0)
+
+        for i in range(tbl_schema["colCount"]):
+            if i != pk_col:
+                available_cols.append(i)
+
+        if available_cols:
+            selected_col = random_choice(available_cols)
+            old_col_name = f"col_{selected_col}"
+            new_col_name = f"col_{selected_col}_renamed"
+
+            alter_stmt = f"ALTER TABLE tbl_{selected_tbl} RENAME COLUMN {old_col_name} TO {new_col_name}"
+            print(f"Renaming column: {alter_stmt}")
+            cur.execute(alter_stmt)
+
+            # Rename it back to maintain consistency
+            cur.execute(f"ALTER TABLE tbl_{selected_tbl} RENAME COLUMN {new_col_name} TO {old_col_name}")
+
+            print(f"Successfully renamed column {old_col_name} (and renamed back)")
+        else:
+            print("No non-primary key columns available to rename")
+
+    con.commit()
+    con_init.commit()
+
+except turso.OperationalError as e:
+    print(f"Failed to alter table: {e}")
+    con.rollback()
+    con_init.rollback()
+except Exception as e:
+    print(f"Unexpected error: {e}")
+    con.rollback()
+    con_init.rollback()
+
+con.close()
+con_init.close()