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new 54389b5dc0d [fix](doc) corr-welford.md: add ORDER BY for deterministic
rows; mirror en/zh examples (#3794)
54389b5dc0d is described below
commit 54389b5dc0db4c0ce19ef6735d24eb56d63bede9
Author: boluor <[email protected]>
AuthorDate: Wed May 27 19:17:07 2026 -0700
[fix](doc) corr-welford.md: add ORDER BY for deterministic rows; mirror
en/zh examples (#3794)
## Summary
Doc page (4.x): \`aggregate-functions/corr-welford.md\` (EN + ZH).
Two problems on this page; this PR fixes both for both sides.
**1. Non-deterministic result tables.** The shared examples on both
sides used hash-partitioned tables without ORDER BY:
\`\`\`sql
select * from test_corr;
select id, corr_welford(k1,k2) from test_corr group by id;
\`\`\`
The documented row orders did not match what the cluster actually
produces on a single-node Apache Doris 4.1.1 cluster (EN's documented
\`select *\` order was \`(1,20,22),(1,10,20)\` but the cluster returns
\`(1,10,20),(1,20,22)\`; the \`group by\` was even more divergent — EN
had \`2,4,3,1\`, ZH had \`1,2,3,4\`, cluster gave \`3,1,2,4\`). Added
\`ORDER BY\` to both queries so users running the snippet see the same
rows as the doc.
**2. Each side was missing one example the other already had.**
- EN gained ZH's \"no valid data → NULL\" example (\`where id = 999\`)
and the matching \"If the group has no valid data, returns NULL\"
return-value bullet.
- ZH gained EN's \`select * from test_corr\` data-sample step.
After this change both pages have the same 4-example structure: setup →
show data → group-by → no-data.
## Verification
Every SQL example was run against a single-node Apache Doris 4.1.1
cluster — the result blocks in this PR are the verbatim mysql client
output.
## Test plan
- [x] Run the full setup + 4 examples on the cluster — all match.
- [x] Compare EN and ZH structurally — same 4 examples in the same
order.
- [x] No prose changes beyond the one-line intro added to the no-data
example.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>
---
.../aggregate-functions/corr-welford.md | 52 +++++++++++++++-------
.../aggregate-functions/corr-welford.md | 43 ++++++++++++------
2 files changed, 65 insertions(+), 30 deletions(-)
diff --git
a/i18n/zh-CN/docusaurus-plugin-content-docs/version-4.x/sql-manual/sql-functions/aggregate-functions/corr-welford.md
b/i18n/zh-CN/docusaurus-plugin-content-docs/version-4.x/sql-manual/sql-functions/aggregate-functions/corr-welford.md
index 1cad2eb765a..bb394239aae 100644
---
a/i18n/zh-CN/docusaurus-plugin-content-docs/version-4.x/sql-manual/sql-functions/aggregate-functions/corr-welford.md
+++
b/i18n/zh-CN/docusaurus-plugin-content-docs/version-4.x/sql-manual/sql-functions/aggregate-functions/corr-welford.md
@@ -55,30 +55,50 @@ insert into test_corr values
```
```sql
-select id,corr_welford(k1,k2) from test_corr group by id;
+select * from test_corr order by id, k1, k2;
```
```text
-+------+---------------------+
-| id | corr_welford(k1,k2) |
-+------+---------------------+
-| 1 | 1 |
-| 2 | 0.4539206495016017 |
-| 3 | NULL |
-| 4 | 0 |
-+------+---------------------+
++------+------+------+
+| id | k1 | k2 |
++------+------+------+
+| 1 | 10 | 20 |
+| 1 | 20 | 22 |
+| 2 | 25 | 20 |
+| 2 | 30 | 22 |
+| 2 | 36 | 21 |
+| 3 | 25 | NULL |
+| 4 | 25 | 20 |
+| 4 | 25 | 21 |
+| 4 | 25 | 22 |
++------+------+------+
```
```sql
-select corr_welford(k1,k2) from test_corr where id=999;
+select id, corr_welford(k1, k2) from test_corr group by id order by id;
```
-组内没有有效数据。
+```text
++------+----------------------+
+| id | corr_welford(k1, k2) |
++------+----------------------+
+| 1 | 1 |
+| 2 | 0.4539206495016017 |
+| 3 | NULL |
+| 4 | 0 |
++------+----------------------+
+```
+
+当分组内没有有效的 `(k1, k2)` 数据对时（此处 `id = 999` 没有匹配行），聚合返回 NULL。
+
+```sql
+select corr_welford(k1, k2) from test_corr where id = 999;
+```
```text
-+---------------------+
-| corr_welford(k1,k2) |
-+---------------------+
-| NULL |
-+---------------------+
++----------------------+
+| corr_welford(k1, k2) |
++----------------------+
+| NULL |
++----------------------+
```
\ No newline at end of file
diff --git
a/versioned_docs/version-4.x/sql-manual/sql-functions/aggregate-functions/corr-welford.md
b/versioned_docs/version-4.x/sql-manual/sql-functions/aggregate-functions/corr-welford.md
index 98055a6a635..ee9f5c588d2 100755
---
a/versioned_docs/version-4.x/sql-manual/sql-functions/aggregate-functions/corr-welford.md
+++
b/versioned_docs/version-4.x/sql-manual/sql-functions/aggregate-functions/corr-welford.md
@@ -29,6 +29,7 @@ Returns a DOUBLE type value, which is the covariance of expr1
and expr2 divided
- If the standard deviation of expr1 or expr2 is 0, returns 0.
- If expr1 or expr2 contains NULL values, those rows are excluded from the
final result.
+- If the group has no valid data, returns NULL.
## Example
@@ -54,36 +55,50 @@ insert into test_corr values
```
```sql
-select * from test_corr;
+select * from test_corr order by id, k1, k2;
```
```text
+------+------+------+
| id | k1 | k2 |
+------+------+------+
-| 1 | 20 | 22 |
| 1 | 10 | 20 |
-| 2 | 36 | 21 |
-| 2 | 30 | 22 |
+| 1 | 20 | 22 |
| 2 | 25 | 20 |
+| 2 | 30 | 22 |
+| 2 | 36 | 21 |
| 3 | 25 | NULL |
+| 4 | 25 | 20 |
| 4 | 25 | 21 |
| 4 | 25 | 22 |
-| 4 | 25 | 20 |
+------+------+------+
```
```sql
-select id,corr_welford(k1,k2) from test_corr group by id;
+select id, corr_welford(k1, k2) from test_corr group by id order by id;
+```
+
+```text
++------+----------------------+
+| id | corr_welford(k1, k2) |
++------+----------------------+
+| 1 | 1 |
+| 2 | 0.4539206495016017 |
+| 3 | NULL |
+| 4 | 0 |
++------+----------------------+
+```
+
+When the group contains no valid `(k1, k2)` pairs (here, no rows match `id =
999`), the aggregate returns NULL.
+
+```sql
+select corr_welford(k1, k2) from test_corr where id = 999;
```
```text
-+------+---------------------+
-| id | corr_welford(k1,k2) |
-+------+---------------------+
-| 2 | 0.4539206495016017 |
-| 4 | 0 |
-| 3 | NULL |
-| 1 | 1 |
-+------+---------------------+
++----------------------+
+| corr_welford(k1, k2) |
++----------------------+
+| NULL |
++----------------------+
```
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