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Posted to notifications@superset.apache.org by "JhonMcLovin (via GitHub)" <gi...@apache.org> on 2026/08/06 11:50:17 UTC
[I] SQL lab returns NULL values when there is data with complex maps. [superset]
JhonMcLovin opened a new issue, #42840:
URL: https://github.com/apache/superset/issues/42840
### Bug description
When using SQLLab for querying map<string,string> returns NULL when there is more than just a string in key.
Example query:
```
SELECT *
FROM (
VALUES (
MAP(
ARRAY['key'],
ARRAY['{"key2":[string]}']
)
)
) AS t(payload);
```
When running this through Athena the result is {key={"key2":[string]}}
However in SQLLab it returns NULL
Similar issue was recently closed:
https://github.com/apache/superset/issues/37363
This is still an issue in Superset 6.1.0
### Screenshots/recordings
_No response_
### Superset version
6.1.0
### Python version
3.12
### Node version
I don't know
### Browser
Not applicable
### Additional context
_No response_
### Checklist
- [x] I have searched Superset docs and Slack and didn't find a solution to my problem.
- [x] I have searched the GitHub issue tracker and didn't find a similar bug report.
- [x] I have checked Superset's logs for errors and if I found a relevant Python stacktrace, I included it here as text in the "additional context" section.
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Re: [I] SQL lab returns NULL values when there is data with complex maps. [superset]
Posted by "bikash-barnwal (via GitHub)" <gi...@apache.org>.
bikash-barnwal commented on issue #42840:
URL: https://github.com/apache/superset/issues/42840#issuecomment-5300749628
This reproduces offline, without an Athena instance, and the data is lost inside `pyathena` before Superset sees it — so the `validation:required` label can be satisfied from a plain Python shell.
Superset's Athena spec supplies no type converter, so pyathena falls back to `DefaultTypeConverter` (`pyathena/result_set.py:594`), which maps `map`/`array`/`row` to its native-format parsers (`pyathena/converter.py:390-412`). Those parsers bail out to `None` on any bracket or parenthesis in the rendered text:
```python
# pyathena/converter.py:181
if any(char in inner for char in "()[]"):
# Contains complex structures (arrays, structs), skip parsing
return None
```
`_to_array` has the same bail at `converter.py:128-130`. Run against pyathena 3.35.4 — the version Superset's own pin resolves to (`pyproject.toml:134`, `pyathena[pandas]>=3.35.2,<4`):
```
'{key={"key2":[string]}}' -> None
'{a=[1, 2]}' -> None
'{a=(1,2)}' -> None
'{note=call me (asap)}' -> None <- plain string, just has parentheses
'{key=hello world}' -> {'key': 'hello world'} (control, parses fine)
```
Note the fourth case: the guard is meant to skip genuinely nested structures, but it fires on ordinary prose that happens to contain a parenthesis. `cursor.fetchall()` hands Superset a literal `None`; there is no value left to serialize.
**Superset's own handling is correct.** The suggestion earlier in the thread that `stringify_values()` fails on bracket-containing values does not hold — #38172 and #41099 are already in `master` (`superset/result_set.py:62-97`). Feeding it the values in question:
```
{'key': {'key2': ['string']}} -> '{"key": {"key2": ["string"]}}'
{'note': 'call me (asap)'} -> '{"note": "call me (asap)"}'
[[1, 2], [3]] -> '[[1, 2], [3]]'
```
All correct.
**Workaround for the reporter:** `CAST(col AS JSON)` routes through `_to_json` (plain `json.loads`) and bypasses the native-format parser entirely.
I did not send a Superset-side patch. One is possible — injecting a custom converter through `AthenaEngineSpec.adjust_engine_params` that falls back to the raw varchar instead of `None` — but it would mean importing pyathena into the engine spec to subclass its converter, papering over a third-party bug that affects every pyathena consumer, and @rusackas said above he is taking this upstream. Worth raising Superset's floor pin once the pyathena fix ships.
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Re: [I] SQL lab returns NULL values when there is data with complex maps. [superset]
Posted by "dosubot[bot] (via GitHub)" <gi...@apache.org>.
dosubot[bot] commented on issue #42840:
URL: https://github.com/apache/superset/issues/42840#issuecomment-5204304825
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<!-- Answer -->
This is the same underlying issue as #37363 — Superset's result serialization pipeline force-stringifies all nested types (MAP, ARRAY, ROW) via `stringify_values()`, which can silently fail and produce NULL when the map values contain special characters like brackets [[1]](https://github.com/apache/superset/blob/829e4d92d91ceae4b43b1ed3b063ffe45377799c/superset/result_set.py#L154-L161). Athena is particularly affected because its engine spec has no custom complex type handling and relies entirely on the default serialization path [[2]](https://github.com/apache/superset/blob/829e4d92d91ceae4b43b1ed3b063ffe45377799c/superset/db_engine_specs/athena.py).
Several PRs have been merged that improve this area:
- [PR #38172](https://github.com/apache/superset/pull/38172) — tracks nested columns before stringification and restores them as Python dict/list objects, which directly addresses this class of bug.
- [PR #41099](https://github.com/apache/superset/pull/41099) — `stringify_values()` now uses JSON encoding instead of Python's `str()` for dict/list values.
**Workaround:** Cast the map column to JSON in your query:
```sql
SELECT CAST(payload AS JSON) FROM ...
```
This avoids the problematic stringification path and was confirmed working in the prior issue [[3]](https://github.com/apache/superset/issues/37363#issuecomment-5124517892).
It would be worth checking whether this is fixed on `master` given the merged PRs above — if it still reproduces there, a failing test case or PR would help the maintainers triage this.
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Re: [I] SQL lab returns NULL values when there is data with complex maps. [superset]
Posted by "rusackas (via GitHub)" <gi...@apache.org>.
rusackas commented on issue #42840:
URL: https://github.com/apache/superset/issues/42840#issuecomment-5768589163
Upstream fixed this in PyAthena 3.36.0 (laughingman7743/PyAthena#763, thanks @seunggabi), so `_to_map` keeps the raw string instead of returning None, and #44195 bumped our floor pin to match. Closing this out. Holler if it still reproduces on 3.36.0+ and I'll reopen.
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Re: [I] SQL lab returns NULL values when there is data with complex maps. [superset]
Posted by "rusackas (via GitHub)" <gi...@apache.org>.
rusackas commented on issue #42840:
URL: https://github.com/apache/superset/issues/42840#issuecomment-5246461449
Dug into this. It's not actually a Superset bug — Superset's own dict/JSON stringification (`stringify_values` in `result_set.py`) already handles values like this correctly, verified against the existing test suite. The value is already `None` by the time it reaches Superset, because `pyathena` converts it internally inside `cursor.fetchall()`.
Traced it to `pyathena/converter.py`'s `_to_map()`. It has a safety check meant to skip genuinely complex/nested map values, but it's too broad: it bails to `None` if the map's *value* contains any of `()[]`, even when those are just plain characters inside a string rather than real Athena map/array syntax. Confirmed directly:
```python
_to_map('{key={"key2":[string]}}') # -> None
_to_map('{key=hello world}') # -> {'key': 'hello world'} (control, works)
```
Workaround in the meantime (same one that worked for #37363): `CAST(payload AS JSON)` in the query, which sidesteps pyathena's native-format parser entirely.
Going to see if there's a reasonable upstream fix and open a PR against pyathena directly, since that's where this actually needs to be fixed. Will link it here.
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Re: [I] SQL lab returns NULL values when there is data with complex maps. [superset]
Posted by "rusackas (via GitHub)" <gi...@apache.org>.
rusackas closed issue #42840: SQL lab returns NULL values when there is data with complex maps.
URL: https://github.com/apache/superset/issues/42840
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