feat: Add --partition flag to migrate only specific partition

Allows testing/debugging by migrating only a single partition instead of
the entire table. Useful for:
- Testing consolidation on specific partitions
- Quick verification of fixes without full migration
- Targeted debugging

Usage:
    python3 main.py migrate full --table ELABDATADISP --partition d10
    python3 main.py migrate full --table RAWDATACOR --partition d11 --resume

Changes:
- Add partition parameter to FullMigrator.migrate()
- Filter partitions list to only specified partition if provided
- Validate partition exists in available partitions
- Add --partition CLI option to migrate full command
- Update message to show partition in progress

🤖 Generated with Claude Code

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

main.py

@@ -74,7 +74,13 @@ def migrate():
     is_flag=True,
     help="Resume from last checkpoint if migration was interrupted"
 )
-def full(table, dry_run, resume):
+@click.option(
+    "--partition",
+    type=str,
+    default=None,
+    help="Only migrate this partition (for testing/debugging)"
+)
+def full(table, dry_run, resume, partition):
     """Perform full migration of all data."""
     setup_logger(__name__)
 
@@ -84,8 +90,8 @@ def full(table, dry_run, resume):
         total_migrated = 0
 
         for tbl in tables:
-            click.echo(f"\nMigrating {tbl}...")
+            click.echo(f"\nMigrating {tbl}" + (f" (partition {partition})" if partition else "") + "...")
-            migrated = run_full_migration(tbl, dry_run=dry_run, resume=resume)
+            migrated = run_full_migration(tbl, dry_run=dry_run, resume=resume, partition=partition)
             total_migrated += migrated
             click.echo(f"✓ {tbl}: {migrated} rows migrated")
 

src/migrator/full_migration.py

@@ -31,12 +31,13 @@ class FullMigrator:
         self.settings = get_settings()
         self.state = MigrationState()
 
-    def migrate(self, dry_run: bool = False, resume: bool = False) -> int:
+    def migrate(self, dry_run: bool = False, resume: bool = False, partition: str = None) -> int:
         """Perform full migration of the table with resume capability.
 
         Args:
             dry_run: If True, log what would be done but don't modify data
             resume: If True, resume from last checkpoint; if False, check for conflicts
+            partition: If specified, only migrate this partition (for testing/debugging)
 
         Returns:
             Total number of rows migrated in this run
@@ -112,6 +113,13 @@ class FullMigrator:
                         partitions = mysql_conn.get_table_partitions(mysql_table)
                         logger.info(f"Found {len(partitions)} partitions for {mysql_table}")
 
+                        # If specific partition requested, filter to just that one
+                        if partition:
+                            if partition not in partitions:
+                                raise ValueError(f"Partition {partition} not found. Available: {partitions}")
+                            partitions = [partition]
+                            logger.info(f"Filtering to only partition: {partition}")
+
                         for partition_idx, partition in enumerate(partitions, 1):
                             # Skip partitions already completed in previous run
                             if last_completed_partition and partition <= last_completed_partition:
@@ -417,7 +425,8 @@ class FullMigrator:
 def run_full_migration(
     table: str,
     dry_run: bool = False,
-    resume: bool = False
+    resume: bool = False,
+    partition: str = None
 ) -> int:
     """Run full migration for a table.
 
@@ -425,9 +434,10 @@ def run_full_migration(
         table: Table name to migrate
         dry_run: If True, show what would be done without modifying data
         resume: If True, resume from last checkpoint instead of starting fresh
+        partition: If specified, only migrate this partition (for testing/debugging)
 
     Returns:
         Number of rows migrated in this run
     """
     migrator = FullMigrator(table)
-    return migrator.migrate(dry_run=dry_run, resume=resume)
+    return migrator.migrate(dry_run=dry_run, resume=resume, partition=partition)