[Feature](func) Support table function json_each, json_each_text#60910
[Feature](func) Support table function json_each, json_each_text#60910linrrzqqq wants to merge 2 commits intoapache:masterfrom
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run buildall |
TPC-H: Total hot run time: 28775 ms |
TPC-DS: Total hot run time: 184699 ms |
BE UT Coverage ReportIncrement line coverage Increment coverage report
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BE Regression && UT Coverage ReportIncrement line coverage Increment coverage report
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run buildall |
TPC-H: Total hot run time: 28938 ms |
TPC-DS: Total hot run time: 184511 ms |
FE UT Coverage ReportIncrement line coverage |
BE UT Coverage ReportIncrement line coverage Increment coverage report
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BE Regression && UT Coverage ReportIncrement line coverage Increment coverage report
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/review |
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/review |
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Code Review Summary: [Feature](func) Support table function json_each, json_each_text
Overall this is a well-structured addition of two new table-generating functions (json_each and json_each_text) that expand JSON objects into key/value rows. The implementation follows existing patterns in the codebase (similar to explode_json_object). The C++ implementation is correct, the FE Java classes follow the established TableGeneratingFunction pattern, and the tests are comprehensive.
Issues Found
1. [Indentation] BuiltinTableGeneratingFunctions.java — json_each_text line has inconsistent indentation
The json_each_text entry has 20 spaces of indentation vs 12 spaces for every other entry in the list. Minor formatting issue.
2. [Missing outer variants] json_each and json_each_text lack _outer variants
Every other table-generating function in Doris (explode, explode_map, explode_json_object, explode_split, explode_numbers, posexplode, etc.) has a corresponding _outer variant that provides LEFT JOIN-like semantics (emitting a NULL row when the input is NULL or empty). json_each/json_each_text are the only table functions without outer variants.
- The BE side (
table_function_factory.cpp) already supports outer semantics automatically (it strips the_outersuffix, looks up the base function, and callsset_outer()). No BE changes are needed. - However, on the FE side: (a)
function_fake.cppusesregister_functioninstead ofregister_table_function_expand_outer, sojson_each_outer/json_each_text_outerare not registered in the BE function factory. (b) NoJsonEachOuter.java/JsonEachTextOuter.javaFE classes exist. (c) No registration inBuiltinTableGeneratingFunctions.javafor the outer variants. - This means
LATERAL VIEW OUTER json_each(...)will not work. - Consider whether this is intentional or an oversight. If intentional, a comment explaining why would be helpful.
3. [Performance] Const column optimization is incomplete
When _is_const = true, the process_row method still re-parses the JSON and rebuilds _kv_pairs on every row. The vexplode_numbers function demonstrates the pattern of pre-computing results in process_init and returning early in process_row when const. This is functionally correct but sub-optimal for queries with const JSON columns and many rows. Not a blocker, but worth noting as a follow-up optimization.
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Nit: Indentation inconsistency. This line has 20 spaces of indentation (5 levels), but every other entry in this list uses 12 spaces (3 levels). Should be aligned with the line above:
tableGenerating(JsonEachText.class, "json_each_text"),
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Code Review Summary: Feature Support table function json_each, json_each_text
Overall this is a clean, well-structured PR that follows existing patterns for adding table generating functions. The code is functionally correct, has good test coverage (unit tests + regression tests), and handles edge cases (NULL input, empty objects, non-object JSON, unicode, nested values) properly.
Issues Found
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[Style] Indentation inconsistency in BuiltinTableGeneratingFunctions.java — The
JsonEachTextregistration line has extra indentation (double-indented) compared to all surrounding entries. Minor style nit. -
[Suggestion] Missing
_outervariants — Unlike most otherexplode_*table functions,json_eachandjson_each_textdo not provide_outervariants (json_each_outer,json_each_text_outer). In the BE,register_functionis used instead ofregister_table_function_expand_outer, and noJsonEachOuter/JsonEachTextOuterFE classes exist. This meansLATERAL VIEW json_each_outer(...)will fail. While there is precedent (e.g.,ExplodeVariantArray,Unnest), this is a usability gap that users may expect to work, especially those coming from PostgreSQL. Consider adding outer variants, or explicitly documenting why they are omitted. -
[Suggestion]
_is_constoptimization not fully utilized —process_initcorrectly detects const columns viaunpack_if_constand sets_is_const, butprocess_rowstill unconditionally re-parses JSON and rebuilds_kv_pairson every call. Since the base classTableFunction::process_rowpreserves_cur_sizewhen_is_constis true, the derived class could skip re-parsing after the first row for const inputs. This matches the existing pattern invexplode_json_object(which also doesn't optimize), but is a missed opportunity for performance improvement with literal/const JSON inputs.
Positive Observations
- Clean template design using
TEXT_MODEbool to share code betweenjson_eachandjson_each_text - Good handling of nullable columns, null JSON values, and edge cases
- Comprehensive regression tests covering: basic types, nulls, empty objects, non-objects, unicode, negative numbers, booleans, nested values, and inline literals
- Unit tests cover both
get_valueandget_same_many_valuespaths - Follows the established visitor pattern and function signature conventions correctly
fe/fe-core/src/main/java/org/apache/doris/catalog/BuiltinTableGeneratingFunctions.java
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/review |
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Code Review Summary: json_each / json_each_text Table Functions
Overall this is a well-structured implementation following existing patterns (particularly explode_json_object). The FE and BE implementations are consistent, the template approach (TEXT_MODE) is clean, and test coverage is reasonable. Below are findings organized by the critical review checkpoints.
Critical Checkpoint Conclusions
1. Goal & Correctness: The PR adds two table functions json_each and json_each_text that expand top-level JSON objects into key/value pairs (JSONB vs text value columns respectively). The implementation accomplishes this goal. Regression tests and unit tests prove the basic functionality.
2. Modification size/focus: The PR is focused and minimal for a new feature. 11 files changed, all related to the feature.
3. Concurrency: No concurrency concerns — table functions execute in a single-threaded pipeline context.
4. Lifecycle management: No special lifecycle concerns. Column pointers are properly nulled in process_close().
5. Configuration items: None added — N/A.
6. Incompatible changes: No incompatible changes — this is purely additive.
7. Parallel code paths (Missing _outer variants): explode_* table function has a corresponding _outer variant (e.g., explode_json_object / explode_json_object_outer). The _outer variant preserves the input row with NULL values when the generator produces zero rows (left-join semantics). json_each and json_each_text are missing their _outer variants. This is a functional gap — users have no way to get outer join behavior with these functions. See inline comments.
8. BE fake function registration: json_each / json_each_text are registered with register_function instead of register_table_function_expand_outer, which is consistent with not having outer variants, but inconsistent with how explode_json_object is registered. If outer variants are added, this needs to change.
9. DCHECK usage in function_fake.cpp: The new FunctionJsonEach and FunctionJsonEachText use DCHECK_EQ for argument type validation. Per coding standards, DCHECK disappears in RELEASE builds, leaving no protection. This should use a proper error return or DORIS_CHECK for invariant assertions. Note: this matches the existing pattern in FunctionExplodeJsonObject, so it's a pre-existing issue, but new code should not perpetuate it.
10. Test coverage: Good breadth — covers basic strings, numbers, booleans, null values, empty objects, SQL NULL input, non-object inputs (arrays, strings), unicode, negative numbers, inline literals, and multi-row scenarios. The BE unit test also covers get_same_many_values. Missing: FE unit tests (pattern exists in ExplodeTest.java), and the id=9 nested object/array test case only runs sql (no qt_ assertion).
11. Observability: N/A for a simple table function.
12. Transaction/persistence: N/A.
13. FE-BE variable passing: The function signatures are correctly matched between FE (JsonType input, Struct(String, JsonType/String) return) and BE (FunctionJsonEach/FunctionJsonEachText fake functions).
14. Formatting: Minor indentation issue in BuiltinTableGeneratingFunctions.java.
Issues Found (by severity)
| # | Severity | File | Issue |
|---|---|---|---|
| 1 | Medium | Multiple | Missing json_each_outer / json_each_text_outer variants |
| 2 | Low | function_fake.cpp |
DCHECK_EQ should be DORIS_CHECK (disappears in RELEASE) |
| 3 | Nit | BuiltinTableGeneratingFunctions.java |
Extra indentation on json_each_text line |
| 4 | Nit | vjson_each.cpp |
compile_check_end.h placed after closing brace of namespace — inconsistent with header |
fe/fe-core/src/main/java/org/apache/doris/catalog/BuiltinTableGeneratingFunctions.java
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run buildall |
TPC-H: Total hot run time: 28705 ms |
TPC-DS: Total hot run time: 183134 ms |
FE UT Coverage ReportIncrement line coverage |
BE UT Coverage ReportIncrement line coverage Increment coverage report
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run buildall |
TPC-H: Total hot run time: 28800 ms |
TPC-DS: Total hot run time: 184829 ms |
BE UT Coverage ReportIncrement line coverage Increment coverage report
|
FE UT Coverage ReportIncrement line coverage |
BE Regression && UT Coverage ReportIncrement line coverage Increment coverage report
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FE Regression Coverage ReportIncrement line coverage |
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/review |
BE Regression && UT Coverage ReportIncrement line coverage Increment coverage report
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FE Regression Coverage ReportIncrement line coverage |
BE Regression && UT Coverage ReportIncrement line coverage Increment coverage report
|
FE Regression Coverage ReportIncrement line coverage |
5 participants
What problem does this PR solve?
Issue Number: close #xxx
Related PR: #xxx
Problem Summary:
Release note
doc: apache/doris-website#3422
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