CIP2017-04-20: Query Combinators for set operations#227
Open
boggle wants to merge 9 commits intoopencypher:masterfrom
Open
CIP2017-04-20: Query Combinators for set operations#227boggle wants to merge 9 commits intoopencypher:masterfrom
boggle wants to merge 9 commits intoopencypher:masterfrom
Conversation
Mats-SX
suggested changes
Apr 24, 2017
| * `CROSS` | ||
| * `THEN` | ||
|
|
||
| Multi-arm query combinators can only appear within a query using the syntax `<query> [<combinator> <query>]+`. |
There was a problem hiding this comment.
I would prefer if the syntax was expressed in EBNF, similar to how other CIPs do that.
query = singleQuery | combinedQuery ;
combinedQuery = singleQuery, queryCombinator, singleQuery ;
queryCombinator = union | intersect | except | otherwise | cross | then ;
union = "UNION", ["MAX" | "ALL"] ;
...
|
|
||
| This does not consider aliasing of subqueries; henceforth set operations over the same argument queries need to repeat the argument subqueries. | ||
|
|
||
| This could be addressed in a future CIP. |
There was a problem hiding this comment.
I'd suggest merging this with the previous paragraph.
| This is due to its syntactic status as a query combinator. | ||
|
|
||
| In contrast to the other query combinators, the standard rules regarding returned record fields do not apply to `THEN`. | ||
| Instead, the set of returned record fields of both arms of `THEN` must be non-overlapping. |
There was a problem hiding this comment.
Why is this required? Isn't this query perfectly reasonable:
RETURN 1 AS one, 2 AS two
THEN
RETURN one + 5 AS one, one + two AS three
And the full statement would return the fields one and three?
Mats-SX
approved these changes
May 4, 2017
technige
reviewed
May 16, 2017
|
|
||
| `OTHERWISE` is not provided by SQL and could be omitted. | ||
|
|
||
| SQL allows `MINUS` as an alias for `EXCEPT`. |
There was a problem hiding this comment.
Acknowledging a potential Pythonic bias, I have a strong preference for MINUS over EXCEPT here. EXCEPT draws to mind exceptions and feels too general as a term. Conversely, MINUS leads to mathematical difference, which is entirely appropriate.
boggle
force-pushed
the
CIP-query-combinators
branch
from
c917667 to
d361d44
Compare
boggle
changed the title
boggle
force-pushed
the
CIP-query-combinators
branch
from
d361d44 to
bdf4be1
Compare
jmarton
added a commit
to jmarton/slizaa-opencypher-xtext
that referenced
this pull request
Dec 29, 2017
This also pushes `union` and `singleQuery` properties down from the RegularQuery
to the new CombinedQuery interface.
This way, SingleQuery is cleaned from those unused properties.
When 3 or more SingleQueries built up a union query, it used to be modeled
as a tree where each union node added one more SingleQuery like
```
S1
UNION
S2
UNION
S3
```
was modeled as
```
RegularQuery
+-singleQuery: RegularQuery
| +-singleQuery: SingleQuery S1
| +-union:
| +-[list entry]: Union
| +-singleQuery: SingleQuery S2
+-union:
+-list entry: Union
+-singleQuery: SingleQuery S3
```
From now, the representation is as follows, where RegularQuery has 2 subclasses:
- SingleQuery used for sole queries not having any UNION clauses
- CombinedQuery used for queries that have at least one query combinator
(UNION in current openCypher, but other set combinators like INTERSECT
are about to come, see opencypher/openCypher#227)
```
CombinedQuery
+-singleQuery: SingleQuery S1
+-union:
+-[list entry]: Union
+-singleQuery: SingleQuery S2
+-[list entry]: Union
+-singleQuery: SingleQuery S3
```
jmarton
added a commit
to jmarton/slizaa-opencypher-xtext
that referenced
this pull request
Dec 30, 2017
This also pushes `union` and `singleQuery` properties down from the RegularQuery
to the new CombinedQuery interface.
This way, SingleQuery is cleaned from those unused properties.
When 3 or more SingleQueries built up a union query, it used to be modeled
as a tree where each union node added one more SingleQuery like
```
S1
UNION
S2
UNION
S3
```
was modeled as
```
RegularQuery
+-singleQuery: RegularQuery
| +-singleQuery: SingleQuery S1
| +-union:
| +-[list entry]: Union
| +-singleQuery: SingleQuery S2
+-union:
+-list entry: Union
+-singleQuery: SingleQuery S3
```
From now, the representation is as follows, where RegularQuery has 2 subclasses:
- SingleQuery used for sole queries not having any UNION clauses
- CombinedQuery used for queries that have at least one query combinator
(UNION in current openCypher, but other set combinators like INTERSECT
are about to come, see opencypher/openCypher#227)
```
CombinedQuery
+-singleQuery: SingleQuery S1
+-union:
+-[list entry]: Union
+-singleQuery: SingleQuery S2
+-[list entry]: Union
+-singleQuery: SingleQuery S3
```
Author
|
This needs to be reflected here. |
jievince
approved these changes
Dec 26, 2022
11 tasks
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
5 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
This addresses #180.
View latest