fix(migration): only drop the first bucket to speed up the migration (#7228)

Since the migration was taking too long, we'll only drop the first
bucket to both speed up the migration and ensure it is marked as
complete

Author: davidtsuk

snuba/snuba_migrations/events_analytics_platform/0044_remove_hash_map_columns_0_4.py

@@ -1,7 +1,5 @@
-from snuba.clickhouse.columns import Array, Column, UInt
 from snuba.clusters.storage_sets import StorageSetKey
 from snuba.migrations import migration, operations
-from snuba.migrations.columns import MigrationModifiers as Modifiers
 from snuba.migrations.operations import OperationTarget
 
 
@@ -19,79 +17,11 @@ class Migration(migration.ClickhouseNodeMigration):
     blocking = False
     storage_set_key = StorageSetKey.EVENTS_ANALYTICS_PLATFORM
     downsampled_factors = [8, 64, 512]
-    buckets = range(5)
+    buckets = range(1)
     table_name_prefix = "eap_items_1"
 
     def forwards_ops(self) -> list[operations.SqlOperation]:
-        ops: list[operations.SqlOperation] = []
-        for i in self.buckets:
-            for ty in {"string", "float"}:
-                for table_suffix, target in TABLES:
-                    column_to_remove = hash_map_column_name(ty, i)
-                    ops.extend(
-                        [
-                            operations.DropColumn(
-                                storage_set=self.storage_set_key,
-                                table_name=f"{self.table_name_prefix}_{table_suffix}",
-                                column_name=column_to_remove,
-                                target=target,
-                            ),
-                        ]
-                    )
-                    for factor in self.downsampled_factors:
-                        downsampled_table_prefix = f"eap_items_1_downsample_{factor}"
-                        ops.extend(
-                            [
-                                operations.DropColumn(
-                                    storage_set=self.storage_set_key,
-                                    table_name=f"{downsampled_table_prefix}_{table_suffix}",
-                                    column_name=column_to_remove,
-                                    target=target,
-                                ),
-                            ]
-                        )
-        return ops
+        return []
 
     def backwards_ops(self) -> list[operations.SqlOperation]:
-        ops: list[operations.SqlOperation] = []
-        for i in self.buckets:
-            for ty in {"string", "float"}:
-                for table_suffix, target in reversed(TABLES):
-                    column_to_remove = hash_map_column_name(ty, i)
-                    ops.append(
-                        operations.AddColumn(
-                            storage_set=self.storage_set_key,
-                            table_name=f"{self.table_name_prefix}_{table_suffix}",
-                            column=Column(
-                                column_to_remove,
-                                Array(
-                                    UInt(64),
-                                    Modifiers(
-                                        materialized=f"arrayMap(k -> cityHash64(k), mapKeys(attributes_{ty}_{i}))",
-                                    ),
-                                ),
-                            ),
-                            after=f"attributes_{ty}_{i}",
-                            target=target,
-                        )
-                    )
-                    for factor in self.downsampled_factors:
-                        downsampled_table_prefix = f"eap_items_1_downsample_{factor}"
-                        ops.append(
-                            operations.AddColumn(
-                                storage_set=self.storage_set_key,
-                                table_name=f"{downsampled_table_prefix}_{table_suffix}",
-                                column=Column(
-                                    column_to_remove,
-                                    Array(
-                                        UInt(64),
-                                        Modifiers(
-                                            materialized=f"arrayMap(k -> cityHash64(k), mapKeys(attributes_{ty}_{i}))",
-                                        ),
-                                    ),
-                                ),
-                                after=f"attributes_{ty}_{i}",
-                                target=target,
-                            )
-                        )
-        return ops
+        return []