Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

SQL: Resolve attributes recursively for improved subquery support (#69765) #70322

Merged
merged 1 commit into from Mar 11, 2021

Conversation

palesz
Copy link
Contributor

@palesz palesz commented Mar 11, 2021

Previously we did not resolve the attributes recursively which meant that if a field or expression was re-aliased multiple times (through multiple levels of subqueries), the aliases were only resolved one level down. This led to failed query translation because ReferenceAttributes were pointing to non-existing attributes during query translation.

For example the query

SELECT i AS j FROM ( SELECT int AS i FROM test) ORDER BY j

failed during translation because the OrderBy resolved the j ReferenceAttribute to another i ReferenceAttribute that was later removed by an Optimization:

OrderBy[[Order[j{r}#4,ASC,LAST]]]                                             ! OrderBy[[Order[i{r}#2,ASC,LAST]]]
\_Project[[j]]                                                                = \_Project[[j]]
  \_Project[[i]]                                                              !   \_EsRelation[test][date{f}#6, some{f}#7, some.string{f}#8, some.string..]
    \_EsRelation[test][date{f}#6, some{f}#7, some.string{f}#8, some.string..] ! 

By resolving the Attributes recursively both j{r} and i{r} will resolve to test.int{f} above:

OrderBy[[Order[test.int{f}#22,ASC,LAST]]]                                     = OrderBy[[Order[test.int{f}#22,ASC,LAST]]]
\_Project[[j]]                                                                = \_Project[[j]]
  \_Project[[i]]                                                              !   \_EsRelation[test][date{f}#6, some{f}#7, some.string{f}#8, some.string..]
    \_EsRelation[test][date{f}#6, some{f}#7, some.string{f}#8, some.string..] ! 

The scope of recursive resolution depends on how the AttributeMap is constructed and populated.

Fixes #67237

…astic#69765)

Previously we did not resolve the attributes recursively which meant that if a field or expression was re-aliased multiple times (through multiple levels of subqueries), the aliases were only resolved one level down. This led to failed query translation because `ReferenceAttribute`s were pointing to non-existing attributes during query translation.

For example the query

```sql
SELECT i AS j FROM ( SELECT int AS i FROM test) ORDER BY j
```

failed during translation because the `OrderBy` resolved the `j` ReferenceAttribute to another `i` ReferenceAttribute that was later removed by an Optimization:

```
OrderBy[[Order[j{r}elastic#4,ASC,LAST]]]                                             ! OrderBy[[Order[i{r}elastic#2,ASC,LAST]]]
\_Project[[j]]                                                                = \_Project[[j]]
  \_Project[[i]]                                                              !   \_EsRelation[test][date{f}elastic#6, some{f}elastic#7, some.string{f}elastic#8, some.string..]
    \_EsRelation[test][date{f}elastic#6, some{f}elastic#7, some.string{f}elastic#8, some.string..] ! 
```

By resolving the `Attributes` recursively both `j{r}` and `i{r}` will resolve to `test.int{f}` above:

```
OrderBy[[Order[test.int{f}elastic#22,ASC,LAST]]]                                     = OrderBy[[Order[test.int{f}elastic#22,ASC,LAST]]]
\_Project[[j]]                                                                = \_Project[[j]]
  \_Project[[i]]                                                              !   \_EsRelation[test][date{f}elastic#6, some{f}elastic#7, some.string{f}elastic#8, some.string..]
    \_EsRelation[test][date{f}elastic#6, some{f}elastic#7, some.string{f}elastic#8, some.string..] ! 
 ```

The scope of recursive resolution depends on how the `AttributeMap` is constructed and populated.

Fixes elastic#67237
@palesz palesz added >bug :Analytics/SQL SQL querying backport Team:QL (Deprecated) Meta label for query languages team v7.13.0 labels Mar 11, 2021
@elasticmachine
Copy link
Collaborator

Pinging @elastic/es-ql (Team:QL)

@palesz palesz merged commit 8bc96fb into elastic:7.x Mar 11, 2021
@palesz palesz deleted the subquery-npe-fix-7.x branch March 11, 2021 21:58
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
:Analytics/SQL SQL querying backport >bug Team:QL (Deprecated) Meta label for query languages team v7.13.0
Projects
None yet
Development

Successfully merging this pull request may close these issues.

None yet

2 participants