diff --git a/.github/workflows/dependency-review.yml b/.github/workflows/dependency-review.yml
index 3eb629246..ba19fc880 100644
--- a/.github/workflows/dependency-review.yml
+++ b/.github/workflows/dependency-review.yml
@@ -20,7 +20,7 @@ jobs:
 
       - name: GitHub dependency vulnerability check
         if: ${{ github.event_name == 'pull_request_target' }}
-        uses: actions/dependency-review-action@v3.0.8
+        uses: actions/dependency-review-action@v3.1.0
         with:
           fail-on-severity: high
 
diff --git a/.github/workflows/version_bump.yml b/.github/workflows/version_bump.yml
index cd0c60d86..24e3ca3c9 100644
--- a/.github/workflows/version_bump.yml
+++ b/.github/workflows/version_bump.yml
@@ -47,7 +47,7 @@ jobs:
 
     - name: Bump version
       id: cz-bump
-      uses: commitizen-tools/commitizen-action@0.18.2
+      uses: commitizen-tools/commitizen-action@0.19.0
       with:
         increment: ${{ github.event.inputs.bump != 'auto' && github.event.inputs.bump || '' }}
         prerelease: ${{ github.event.inputs.prerelease != 'none' && github.event.inputs.prerelease || '' }}
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 790d0e39e..ee4bbb920 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -43,7 +43,7 @@ repos:
   - id: check-readthedocs
 
 - repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.0.287
+  rev: v0.0.288
   hooks:
   - id: ruff
     args: [--fix, --exit-non-zero-on-fix, --show-fixes]
@@ -53,7 +53,7 @@ repos:
       )$
 
 - repo: https://github.com/psf/black
-  rev: 23.7.0
+  rev: 23.9.1
   hooks:
   - id: black
     exclude: |
diff --git a/poetry.lock b/poetry.lock
index fe68114e5..1e7548e63 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -1107,6 +1107,16 @@ files = [
     {file = "MarkupSafe-2.1.3-cp311-cp311-musllinux_1_1_x86_64.whl", hash = "sha256:5bbe06f8eeafd38e5d0a4894ffec89378b6c6a625ff57e3028921f8ff59318ac"},
     {file = "MarkupSafe-2.1.3-cp311-cp311-win32.whl", hash = "sha256:dd15ff04ffd7e05ffcb7fe79f1b98041b8ea30ae9234aed2a9168b5797c3effb"},
     {file = "MarkupSafe-2.1.3-cp311-cp311-win_amd64.whl", hash = "sha256:134da1eca9ec0ae528110ccc9e48041e0828d79f24121a1a146161103c76e686"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-macosx_10_9_universal2.whl", hash = "sha256:f698de3fd0c4e6972b92290a45bd9b1536bffe8c6759c62471efaa8acb4c37bc"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-macosx_10_9_x86_64.whl", hash = "sha256:aa57bd9cf8ae831a362185ee444e15a93ecb2e344c8e52e4d721ea3ab6ef1823"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:ffcc3f7c66b5f5b7931a5aa68fc9cecc51e685ef90282f4a82f0f5e9b704ad11"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:47d4f1c5f80fc62fdd7777d0d40a2e9dda0a05883ab11374334f6c4de38adffd"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-manylinux_2_5_i686.manylinux1_i686.manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:1f67c7038d560d92149c060157d623c542173016c4babc0c1913cca0564b9939"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-musllinux_1_1_aarch64.whl", hash = "sha256:9aad3c1755095ce347e26488214ef77e0485a3c34a50c5a5e2471dff60b9dd9c"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-musllinux_1_1_i686.whl", hash = "sha256:14ff806850827afd6b07a5f32bd917fb7f45b046ba40c57abdb636674a8b559c"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-musllinux_1_1_x86_64.whl", hash = "sha256:8f9293864fe09b8149f0cc42ce56e3f0e54de883a9de90cd427f191c346eb2e1"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-win32.whl", hash = "sha256:715d3562f79d540f251b99ebd6d8baa547118974341db04f5ad06d5ea3eb8007"},
+    {file = "MarkupSafe-2.1.3-cp312-cp312-win_amd64.whl", hash = "sha256:1b8dd8c3fd14349433c79fa8abeb573a55fc0fdd769133baac1f5e07abf54aeb"},
     {file = "MarkupSafe-2.1.3-cp37-cp37m-macosx_10_9_x86_64.whl", hash = "sha256:8e254ae696c88d98da6555f5ace2279cf7cd5b3f52be2b5cf97feafe883b58d2"},
     {file = "MarkupSafe-2.1.3-cp37-cp37m-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:cb0932dc158471523c9637e807d9bfb93e06a95cbf010f1a38b98623b929ef2b"},
     {file = "MarkupSafe-2.1.3-cp37-cp37m-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:9402b03f1a1b4dc4c19845e5c749e3ab82d5078d16a2a4c2cd2df62d57bb0707"},
@@ -1684,13 +1694,13 @@ files = [
 
 [[package]]
 name = "pytest"
-version = "7.4.1"
+version = "7.4.2"
 description = "pytest: simple powerful testing with Python"
 optional = false
 python-versions = ">=3.7"
 files = [
-    {file = "pytest-7.4.1-py3-none-any.whl", hash = "sha256:460c9a59b14e27c602eb5ece2e47bec99dc5fc5f6513cf924a7d03a578991b1f"},
-    {file = "pytest-7.4.1.tar.gz", hash = "sha256:2f2301e797521b23e4d2585a0a3d7b5e50fdddaaf7e7d6773ea26ddb17c213ab"},
+    {file = "pytest-7.4.2-py3-none-any.whl", hash = "sha256:1d881c6124e08ff0a1bb75ba3ec0bfd8b5354a01c194ddd5a0a870a48d99b002"},
+    {file = "pytest-7.4.2.tar.gz", hash = "sha256:a766259cfab564a2ad52cb1aae1b881a75c3eb7e34ca3779697c23ed47c47069"},
 ]
 
 [package.dependencies]
diff --git a/samples/sample_custom_sql_adapter/__init__.py b/samples/sample_custom_sql_adapter/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/samples/sample_custom_sql_adapter/connector.py b/samples/sample_custom_sql_adapter/connector.py
new file mode 100644
index 000000000..6f7745a73
--- /dev/null
+++ b/samples/sample_custom_sql_adapter/connector.py
@@ -0,0 +1,32 @@
+from __future__ import annotations
+
+import typing as t
+
+from sqlalchemy.engine.default import DefaultDialect
+
+if t.TYPE_CHECKING:
+    from types import ModuleType
+
+
+class CustomSQLDialect(DefaultDialect):
+    """Custom SQLite dialect that supports JSON."""
+
+    name = "myrdbms"
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+    @classmethod
+    def import_dbapi(cls):
+        """Import the sqlite3 DBAPI."""
+        import sqlite3
+
+        return sqlite3
+
+    @classmethod
+    def dbapi(cls) -> ModuleType:  # type: ignore[override]
+        """Return the DBAPI module.
+
+        NOTE: This is a legacy method that will stop being used by SQLAlchemy at some point.
+        """  # noqa: E501
+        return cls.import_dbapi()
diff --git a/singer_sdk/connectors/sql.py b/singer_sdk/connectors/sql.py
index 8ed4e10f1..2693bfe2e 100644
--- a/singer_sdk/connectors/sql.py
+++ b/singer_sdk/connectors/sql.py
@@ -321,12 +321,21 @@ def create_engine(self) -> Engine:
         Returns:
             A new SQLAlchemy Engine.
         """
-        return sqlalchemy.create_engine(
-            self.sqlalchemy_url,
-            echo=False,
-            json_serializer=self.serialize_json,
-            json_deserializer=self.deserialize_json,
-        )
+        try:
+            return sqlalchemy.create_engine(
+                self.sqlalchemy_url,
+                echo=False,
+                json_serializer=self.serialize_json,
+                json_deserializer=self.deserialize_json,
+            )
+        except TypeError:
+            self.logger.exception(
+                "Retrying engine creation with fewer arguments due to TypeError.",
+            )
+            return sqlalchemy.create_engine(
+                self.sqlalchemy_url,
+                echo=False,
+            )
 
     def quote(self, name: str) -> str:
         """Quote a name if it needs quoting, using '.' as a name-part delimiter.
diff --git a/singer_sdk/helpers/_flattening.py b/singer_sdk/helpers/_flattening.py
index 02585dd80..397044bb6 100644
--- a/singer_sdk/helpers/_flattening.py
+++ b/singer_sdk/helpers/_flattening.py
@@ -4,12 +4,12 @@
 
 import collections
 import itertools
-import json
 import re
 import typing as t
 from copy import deepcopy
 
 import inflection
+import simplejson as json
 
 DEFAULT_FLATTENING_SEPARATOR = "__"
 
@@ -155,17 +155,7 @@ def flatten_schema(
           "type": "string"
         },
         "foo__bar": {
-          "type": "object",
-          "properties": {
-            "baz": {
-              "type": "object",
-              "properties": {
-                "qux": {
-                  "type": "string"
-                }
-              }
-            }
-          }
+          "type": "string"
         }
       }
     }
@@ -178,12 +168,7 @@ def flatten_schema(
           "type": "string"
         },
         "foo__bar__baz": {
-          "type": "object",
-          "properties": {
-            "qux": {
-              "type": "string"
-            }
-          }
+          "type": "string"
         }
       }
     }
@@ -210,7 +195,7 @@ def flatten_schema(
     return new_schema
 
 
-def _flatten_schema(  # noqa: C901
+def _flatten_schema(  # noqa: C901, PLR0912
     schema_node: dict,
     parent_keys: list[str] | None = None,
     separator: str = "__",
@@ -249,6 +234,8 @@ def _flatten_schema(  # noqa: C901
                         max_level=max_level,
                     ).items(),
                 )
+            elif "array" in v["type"] or "object" in v["type"] and max_level > 0:
+                items.append((new_key, {"type": "string"}))
             else:
                 items.append((new_key, v))
         elif len(v.values()) > 0:
@@ -347,7 +334,7 @@ def _flatten_record(
             items.append(
                 (
                     new_key,
-                    json.dumps(v)
+                    json.dumps(v, use_decimal=True)
                     if _should_jsondump_value(k, v, flattened_schema)
                     else v,
                 ),
diff --git a/tests/core/test_connector_sql.py b/tests/core/test_connector_sql.py
index 58ba59ec7..101d2d399 100644
--- a/tests/core/test_connector_sql.py
+++ b/tests/core/test_connector_sql.py
@@ -1,15 +1,19 @@
 from __future__ import annotations
 
+import typing as t
 from decimal import Decimal
 from unittest import mock
 
 import pytest
 import sqlalchemy
-from sqlalchemy.dialects import sqlite
+from sqlalchemy.dialects import registry, sqlite
 
 from singer_sdk.connectors import SQLConnector
 from singer_sdk.exceptions import ConfigValidationError
 
+if t.TYPE_CHECKING:
+    from sqlalchemy.engine import Engine
+
 
 def stringify(in_dict):
     return {k: str(v) for k, v in in_dict.items()}
@@ -283,3 +287,18 @@ def test_engine_json_serialization(self, connector: SQLConnector):
                 (1, {"x": Decimal("1.0")}),
                 (2, {"x": Decimal("2.0"), "y": [1, 2, 3]}),
             ]
+
+
+def test_adapter_without_json_serde():
+    registry.register(
+        "myrdbms",
+        "samples.sample_custom_sql_adapter.connector",
+        "CustomSQLDialect",
+    )
+
+    class CustomConnector(SQLConnector):
+        def create_engine(self) -> Engine:
+            return super().create_engine()
+
+    connector = CustomConnector(config={"sqlalchemy_url": "myrdbms:///"})
+    connector.create_engine()
diff --git a/tests/core/test_mapper.py b/tests/core/test_mapper.py
index 036d7586a..1cc214810 100644
--- a/tests/core/test_mapper.py
+++ b/tests/core/test_mapper.py
@@ -8,6 +8,7 @@
 import logging
 import typing as t
 from contextlib import redirect_stdout
+from decimal import Decimal
 
 import pytest
 from freezegun import freeze_time
@@ -19,7 +20,9 @@
 from singer_sdk.streams.core import Stream
 from singer_sdk.tap_base import Tap
 from singer_sdk.typing import (
+    ArrayType,
     IntegerType,
+    NumberType,
     ObjectType,
     PropertiesList,
     Property,
@@ -415,6 +418,7 @@ class MappedStream(Stream):
             ObjectType(
                 Property("id", IntegerType()),
                 Property("sub", ObjectType(Property("num", IntegerType()))),
+                Property("some_numbers", ArrayType(NumberType())),
             ),
         ),
     ).to_dict()
@@ -423,17 +427,29 @@ def get_records(self, context):  # noqa: ARG002
         yield {
             "email": "alice@example.com",
             "count": 21,
-            "user": {"id": 1, "sub": {"num": 1}},
+            "user": {
+                "id": 1,
+                "sub": {"num": 1},
+                "some_numbers": [Decimal("3.14"), Decimal("2.718")],
+            },
         }
         yield {
             "email": "bob@example.com",
             "count": 13,
-            "user": {"id": 2, "sub": {"num": 2}},
+            "user": {
+                "id": 2,
+                "sub": {"num": 2},
+                "some_numbers": [Decimal("10.32"), Decimal("1.618")],
+            },
         }
         yield {
             "email": "charlie@example.com",
             "count": 19,
-            "user": {"id": 3, "sub": {"num": 3}},
+            "user": {
+                "id": 3,
+                "sub": {"num": 3},
+                "some_numbers": [Decimal("1.414"), Decimal("1.732")],
+            },
         }
 
 
@@ -545,6 +561,13 @@ def _clear_schema_cache() -> None:
             "aliased_stream.jsonl",
             id="aliased_stream",
         ),
+        pytest.param(
+            {},
+            True,
+            0,
+            "flatten_depth_0.jsonl",
+            id="flatten_depth_0",
+        ),
         pytest.param(
             {},
             True,
diff --git a/tests/snapshots/mapped_stream/aliased_stream.jsonl b/tests/snapshots/mapped_stream/aliased_stream.jsonl
index 46d5daffe..8df28ddf4 100644
--- a/tests/snapshots/mapped_stream/aliased_stream.jsonl
+++ b/tests/snapshots/mapped_stream/aliased_stream.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "aliased_stream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "aliased_stream", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "aliased_stream", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "aliased_stream", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "aliased_stream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}, "some_numbers": {"items": {"type": ["number"]}, "type": ["array", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "aliased_stream", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}, "some_numbers": [3.14, 2.718]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "aliased_stream", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}, "some_numbers": [10.32, 1.618]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "aliased_stream", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}, "some_numbers": [1.414, 1.732]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/drop_property.jsonl b/tests/snapshots/mapped_stream/drop_property.jsonl
index 8694f4736..aece20a30 100644
--- a/tests/snapshots/mapped_stream/drop_property.jsonl
+++ b/tests/snapshots/mapped_stream/drop_property.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "mystream", "record": {"count": 21, "user": {"id": 1, "sub": {"num": 1}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"count": 13, "user": {"id": 2, "sub": {"num": 2}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"count": 19, "user": {"id": 3, "sub": {"num": 3}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}, "some_numbers": {"items": {"type": ["number"]}, "type": ["array", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "mystream", "record": {"count": 21, "user": {"id": 1, "sub": {"num": 1}, "some_numbers": [3.14, 2.718]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"count": 13, "user": {"id": 2, "sub": {"num": 2}, "some_numbers": [10.32, 1.618]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"count": 19, "user": {"id": 3, "sub": {"num": 3}, "some_numbers": [1.414, 1.732]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/drop_property_null_string.jsonl b/tests/snapshots/mapped_stream/drop_property_null_string.jsonl
index 8694f4736..aece20a30 100644
--- a/tests/snapshots/mapped_stream/drop_property_null_string.jsonl
+++ b/tests/snapshots/mapped_stream/drop_property_null_string.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "mystream", "record": {"count": 21, "user": {"id": 1, "sub": {"num": 1}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"count": 13, "user": {"id": 2, "sub": {"num": 2}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"count": 19, "user": {"id": 3, "sub": {"num": 3}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}, "some_numbers": {"items": {"type": ["number"]}, "type": ["array", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "mystream", "record": {"count": 21, "user": {"id": 1, "sub": {"num": 1}, "some_numbers": [3.14, 2.718]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"count": 13, "user": {"id": 2, "sub": {"num": 2}, "some_numbers": [10.32, 1.618]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"count": 19, "user": {"id": 3, "sub": {"num": 3}, "some_numbers": [1.414, 1.732]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/flatten_all.jsonl b/tests/snapshots/mapped_stream/flatten_all.jsonl
index c54db1563..9a1b53b5b 100644
--- a/tests/snapshots/mapped_stream/flatten_all.jsonl
+++ b/tests/snapshots/mapped_stream/flatten_all.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user__id": {"type": ["integer", "null"]}, "user__sub__num": {"type": ["integer", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user__id": 1, "user__sub__num": 1}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user__id": 2, "user__sub__num": 2}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user__id": 3, "user__sub__num": 3}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user__id": {"type": ["integer", "null"]}, "user__sub__num": {"type": ["integer", "null"]}, "user__some_numbers": {"type": "string"}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user__id": 1, "user__sub__num": 1, "user__some_numbers": "[3.14, 2.718]"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user__id": 2, "user__sub__num": 2, "user__some_numbers": "[10.32, 1.618]"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user__id": 3, "user__sub__num": 3, "user__some_numbers": "[1.414, 1.732]"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/flatten_depth_0.jsonl b/tests/snapshots/mapped_stream/flatten_depth_0.jsonl
new file mode 100644
index 000000000..7a8b54581
--- /dev/null
+++ b/tests/snapshots/mapped_stream/flatten_depth_0.jsonl
@@ -0,0 +1,6 @@
+{"type": "STATE", "value": {}}
+{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}, "some_numbers": {"items": {"type": ["number"]}, "type": ["array", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}, "some_numbers": [3.14, 2.718]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}, "some_numbers": [10.32, 1.618]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}, "some_numbers": [1.414, 1.732]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/flatten_depth_1.jsonl b/tests/snapshots/mapped_stream/flatten_depth_1.jsonl
index 275e3295c..ab5f3a30b 100644
--- a/tests/snapshots/mapped_stream/flatten_depth_1.jsonl
+++ b/tests/snapshots/mapped_stream/flatten_depth_1.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user__id": {"type": ["integer", "null"]}, "user__sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user__id": 1, "user__sub": "{\"num\": 1}"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user__id": 2, "user__sub": "{\"num\": 2}"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user__id": 3, "user__sub": "{\"num\": 3}"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user__id": {"type": ["integer", "null"]}, "user__sub": {"type": "string"}, "user__some_numbers": {"type": "string"}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user__id": 1, "user__sub": "{\"num\": 1}", "user__some_numbers": "[3.14, 2.718]"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user__id": 2, "user__sub": "{\"num\": 2}", "user__some_numbers": "[10.32, 1.618]"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user__id": 3, "user__sub": "{\"num\": 3}", "user__some_numbers": "[1.414, 1.732]"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/keep_all_fields.jsonl b/tests/snapshots/mapped_stream/keep_all_fields.jsonl
index 13ddce438..da476f6a5 100644
--- a/tests/snapshots/mapped_stream/keep_all_fields.jsonl
+++ b/tests/snapshots/mapped_stream/keep_all_fields.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}}, "type": ["object", "null"]}, "email_hash": {"type": ["string", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}}, "email_hash": "c160f8cc69a4f0bf2b0362752353d060"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}}, "email_hash": "4b9bb80620f03eb3719e0a061c14283d"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}}, "email_hash": "426b189df1e2f359efe6ee90f2d2030f"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}, "some_numbers": {"items": {"type": ["number"]}, "type": ["array", "null"]}}, "type": ["object", "null"]}, "email_hash": {"type": ["string", "null"]}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}, "some_numbers": [3.14, 2.718]}, "email_hash": "c160f8cc69a4f0bf2b0362752353d060"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}, "some_numbers": [10.32, 1.618]}, "email_hash": "4b9bb80620f03eb3719e0a061c14283d"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}, "some_numbers": [1.414, 1.732]}, "email_hash": "426b189df1e2f359efe6ee90f2d2030f"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/map_and_flatten.jsonl b/tests/snapshots/mapped_stream/map_and_flatten.jsonl
index bf2620184..a82a124f7 100644
--- a/tests/snapshots/mapped_stream/map_and_flatten.jsonl
+++ b/tests/snapshots/mapped_stream/map_and_flatten.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user__id": {"type": ["integer", "null"]}, "user__sub__num": {"type": ["integer", "null"]}, "email_hash": {"type": ["string", "null"]}}, "type": "object"}, "key_properties": ["email_hash"]}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user__id": 1, "user__sub__num": 1, "email_hash": "c160f8cc69a4f0bf2b0362752353d060"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user__id": 2, "user__sub__num": 2, "email_hash": "4b9bb80620f03eb3719e0a061c14283d"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user__id": 3, "user__sub__num": 3, "email_hash": "426b189df1e2f359efe6ee90f2d2030f"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user__id": {"type": ["integer", "null"]}, "user__sub__num": {"type": ["integer", "null"]}, "user__some_numbers": {"type": "string"}, "email_hash": {"type": ["string", "null"]}}, "type": "object"}, "key_properties": ["email_hash"]}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user__id": 1, "user__sub__num": 1, "user__some_numbers": "[3.14, 2.718]", "email_hash": "c160f8cc69a4f0bf2b0362752353d060"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user__id": 2, "user__sub__num": 2, "user__some_numbers": "[10.32, 1.618]", "email_hash": "4b9bb80620f03eb3719e0a061c14283d"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user__id": 3, "user__sub__num": 3, "user__some_numbers": "[1.414, 1.732]", "email_hash": "426b189df1e2f359efe6ee90f2d2030f"}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/no_map.jsonl b/tests/snapshots/mapped_stream/no_map.jsonl
index 019b1f9d9..7a8b54581 100644
--- a/tests/snapshots/mapped_stream/no_map.jsonl
+++ b/tests/snapshots/mapped_stream/no_map.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "mystream", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}, "some_numbers": {"items": {"type": ["number"]}, "type": ["array", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}, "some_numbers": [3.14, 2.718]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}, "some_numbers": [10.32, 1.618]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "mystream", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}, "some_numbers": [1.414, 1.732]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/sourced_stream_1.jsonl b/tests/snapshots/mapped_stream/sourced_stream_1.jsonl
index e63d03815..a68add19c 100644
--- a/tests/snapshots/mapped_stream/sourced_stream_1.jsonl
+++ b/tests/snapshots/mapped_stream/sourced_stream_1.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "sourced_stream_1", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "sourced_stream_1", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}, "some_numbers": {"items": {"type": ["number"]}, "type": ["array", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}, "some_numbers": [3.14, 2.718]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}, "some_numbers": [10.32, 1.618]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}, "some_numbers": [1.414, 1.732]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/sourced_stream_1_null_string.jsonl b/tests/snapshots/mapped_stream/sourced_stream_1_null_string.jsonl
index e63d03815..a68add19c 100644
--- a/tests/snapshots/mapped_stream/sourced_stream_1_null_string.jsonl
+++ b/tests/snapshots/mapped_stream/sourced_stream_1_null_string.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "sourced_stream_1", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "sourced_stream_1", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}, "some_numbers": {"items": {"type": ["number"]}, "type": ["array", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}, "some_numbers": [3.14, 2.718]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}, "some_numbers": [10.32, 1.618]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "sourced_stream_1", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}, "some_numbers": [1.414, 1.732]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}
diff --git a/tests/snapshots/mapped_stream/sourced_stream_2.jsonl b/tests/snapshots/mapped_stream/sourced_stream_2.jsonl
index 41cce23d7..234551006 100644
--- a/tests/snapshots/mapped_stream/sourced_stream_2.jsonl
+++ b/tests/snapshots/mapped_stream/sourced_stream_2.jsonl
@@ -1,6 +1,6 @@
 {"type": "STATE", "value": {}}
-{"type": "SCHEMA", "stream": "sourced_stream_2", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
-{"type": "RECORD", "stream": "sourced_stream_2", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "sourced_stream_2", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
-{"type": "RECORD", "stream": "sourced_stream_2", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "SCHEMA", "stream": "sourced_stream_2", "schema": {"properties": {"email": {"type": ["string", "null"]}, "count": {"type": ["integer", "null"]}, "user": {"properties": {"id": {"type": ["integer", "null"]}, "sub": {"properties": {"num": {"type": ["integer", "null"]}}, "type": ["object", "null"]}, "some_numbers": {"items": {"type": ["number"]}, "type": ["array", "null"]}}, "type": ["object", "null"]}}, "type": "object"}, "key_properties": []}
+{"type": "RECORD", "stream": "sourced_stream_2", "record": {"email": "alice@example.com", "count": 21, "user": {"id": 1, "sub": {"num": 1}, "some_numbers": [3.14, 2.718]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "sourced_stream_2", "record": {"email": "bob@example.com", "count": 13, "user": {"id": 2, "sub": {"num": 2}, "some_numbers": [10.32, 1.618]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
+{"type": "RECORD", "stream": "sourced_stream_2", "record": {"email": "charlie@example.com", "count": 19, "user": {"id": 3, "sub": {"num": 3}, "some_numbers": [1.414, 1.732]}}, "time_extracted": "2022-01-01T00:00:00+00:00"}
 {"type": "STATE", "value": {"bookmarks": {"mystream": {}}}}