[fix](doc) document json_extract no-auto-broadcast over arrays#3749
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morningman merged 2 commits intoMay 23, 2026
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Issue apache#3318: a user upgrading from Doris 2.0.2 to 2.1.11 noticed the same SQL returned different results: `json_extract('<array-of-objects>', '$.k')` returned `[v1, v2, ...]` on 2.0.2 but `NULL` on 2.1.11. The 2.1+ behavior is intentional and engine-correct, aligning with MySQL's `JSON_EXTRACT` semantics: `$.k` traverses only object members and does not auto-broadcast over array elements. Verified in `be/src/util/jsonb_document.h::findValue` (MEMBER_CODE returns nullptr when pval is not an object) on `branch-2.1`, `branch-3.0`, `branch-3.1`, `branch-4.0`, `branch-4.1`. Doc did not previously call this out. Add a line to each of the 8 maintained version json-extract pages (current/2.1/3.x/4.x, EN + zh) explaining: - `$.k` on an array returns NULL — no auto-broadcast - Use `$[i].k` for index access - Array-wildcard broadcasting via `$[*].k` was introduced in 4.0 (the wildcard `continue` on 2.1/3.x does not actually iterate elements — verified by reading `findValue` on each release branch) - For 2.1/3.x, suggest `LATERAL VIEW EXPLODE` patterns for per-element extraction Closes apache#3318
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Issue apache#3318 reports that json_extract returns NULL when $.k is applied over a JSON array, with no clear path to the broadcasted result the user wants. The existing description note explains $[*].k as the 4.0+ solution but provides no runnable example. Add example 11 to the current and 4.x docs (EN + zh) contrasting $.k (NULL) and $[*].k (broadcasted array). Outputs verified against a 4.x cluster. Not added to 2.1/3.x docs since $[*].k returns NULL there too — the description already notes "supported from Doris 4.0 onward". Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Fixes #3318. A user upgrading from Doris 2.0.2 to 2.1.11 reported that the same SQL changed result:
```sql
SELECT json_extract(product_specific, '$.categoryId')
FROM ods_product_goods_full;
-- product_specific is varchar holding e.g. [{"categoryId":1000},{"categoryId":1003},...]
-- 2.0.2 returned [1000,1003,1006,1012,2,1015]
-- 2.1.11 returns NULL
```
The 2.1+ behavior is intentional and engine-correct: `$.k` traverses only object members and does not auto-broadcast over array elements (aligning with MySQL's `JSON_EXTRACT` semantics). Verified in `be/src/util/jsonb_document.h::findValue` on `branch-2.1`, `branch-3.0`, `branch-3.1`, `branch-4.0`, `branch-4.1`: the `MEMBER_CODE` case returns `nullptr` when `pval` is not a `T_Object`.
The doc previously did not call this out. This PR adds a single line to the path-syntax section on each of the 8 maintained version pages (current/2.1/3.x/4.x EN+zh):
Scope
8 files, +12 lines:
No existing examples changed; no behavior change in the engine.
Test plan
Closes #3318