Subclauses CIP #200

Mats-SX · Mar 6, 2017

This CIP is in response to #194

CIP

petraselmer · Mar 6, 2017

petraselmer requested changes Mar 6, 2017

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Nice one! Just a few comments

petraselmer · Mar 6, 2017

cip/1.accepted/CIP2017-03-01-SKIP-and-LIMIT.adoc

+
+== Background
+
+This CIP is a proposal in answer to link:https://github.com/opencypher/openCypher/issues/194[CIR-2017-194].


"answer" -> "response"

petraselmer · Mar 6, 2017

cip/1.accepted/CIP2017-03-01-SKIP-and-LIMIT.adoc

+=== Semantics
+
+The `LIMIT` subclause prevents records passing through its parent clause after the specified amount of rows, as determined by the limit expression, has been processed.
+For these semantics to be well defined, the limit expression must be constant over the query lifetime, such as parameters or literals.


Can this be expanded on a bit more? It's not 100% clear what is being said. If need be, an example could be provided.

Expanded and gave two examples.

petraselmer · Mar 6, 2017

cip/1.accepted/CIP2017-03-01-SKIP-and-LIMIT.adoc

+
+==== Updating queries
+
+The use of `LIMIT` opens the possibility for certain performance optimisations.


"opens the possibility" -> "opens up the possibility"

petraselmer · Mar 6, 2017

cip/1.accepted/CIP2017-03-01-SKIP-and-LIMIT.adoc

+
+=== Semantics
+
+The `LIMIT` subclause prevents records passing through its parent clause after the specified amount of rows, as determined by the limit expression, has been processed.


"limit expression" -> hmmm... it reads a bit awkwardly at present. Maybe something such as "expression provided to the LIMIT clause" or something. Maybe even formatting would help, such as all in italics, or LIMIT expression?

How about

the expression used as argument to LIMIT

?

That works - just include "the argument"

petraselmer · Mar 6, 2017

cip/1.accepted/CIP2017-03-01-SKIP-and-LIMIT.adoc

+==== Updating queries
+
+The use of `LIMIT` opens the possibility for certain performance optimisations.
+Clauses that come early in the query do not have to be evaluated over the full dataset, just enough to reach the subsequent limit.


"that come early" -> "appearing earlier"

"do not have to be evaluated over the full dataset, just enough to reach the subsequent limit."
->
"only need to be evaluated until the limit is reached, as opposed to evaluating the entire dataset."

petraselmer · Mar 6, 2017

cip/1.accepted/CIP2017-03-01-SKIP-and-LIMIT.adoc

+Clauses that come early in the query do not have to be evaluated over the full dataset, just enough to reach the subsequent limit.
+These optimisations are however not always applicable in combination with updating clauses.
+Semantics between clauses is defined such that _all_ of a previous clause is processed (logically) before _any_ of a subsequent clause is processed.
+This means that _all_ side effects must happen before a `LIMIT` is allowed to halt the processing of records in preceding clauses.


"halt" -> "terminate"

petraselmer · Mar 6, 2017

cip/1.accepted/CIP2017-03-01-SKIP-and-LIMIT.adoc

+Semantics between clauses is defined such that _all_ of a previous clause is processed (logically) before _any_ of a subsequent clause is processed.
+This means that _all_ side effects must happen before a `LIMIT` is allowed to halt the processing of records in preceding clauses.
+
+Consider the below query:


"below query"
->
"following query"

petraselmer · Mar 6, 2017

cip/1.accepted/CIP2017-03-01-SKIP-and-LIMIT.adoc

+
+Consider the below query:
+
+.Create a producer for each item, return first 100 product ids.


Format "producer"

"item, return first 100 product ids"
->
"item, returning the first 100 product ids"

I don't think producer needs formatting here. The example talks about items and producers as concepts, and I think it's clear that these are then represented by nodes with matching labels.

petraselmer · Mar 6, 2017

cip/1.accepted/CIP2017-03-01-SKIP-and-LIMIT.adoc

+
+If the user intention is to only do a partial update of the graph, the query must be rewritten:
+
+.Create a producer for the 100 first items, return their product ids.


"100 first items, return their product ids"
->
"top 100 items, and return their product ids"

Format "producer"

petraselmer · Mar 8, 2017

petraselmer approved these changes Mar 8, 2017

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thobe · Mar 30, 2017

thobe requested changes Mar 30, 2017

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This should be extended to also include ORDER BY, and SKIP.

In fact all of the following sub-clauses should always go together:

WHERE
ORDER BY
SKIP
LIMIT

Mats-SX · Mar 31, 2017

@thobe Extended!

Mats-SX added the CIP label Mar 6, 2017

Add the LIMIT CIP
Fixes #194

2967f79

Add example for how only constant expressions are allowed
- Rename file to correct name for the CIP - Improve language

3a3f198

Mats-SX added some commits Mar 31, 2017

Change title to `Subclauses`

aa6a008

Add SKIP, WHERE and ORDER BY

2343256

Mats-SX changed the title from Add the LIMIT CIP to Add the Subclauses CIP Mar 31, 2017

Reorder subclauses to be consistent with grammar order

5339768

Mats-SX changed the title from Add the Subclauses CIP to Subclauses CIP May 5, 2017

Reformatted title

3369038

opencypher/openCypher

Subclauses CIP #200

Mats-SX commented Mar 6, 2017 •

edited

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Mats-SX changed the title from Add the LIMIT CIP to Add the Subclauses CIP Mar 31, 2017

Mats-SX changed the title from Add the Subclauses CIP to Subclauses CIP May 5, 2017

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Mats-SX commented Mar 6, 2017 • edited

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petraselmer approved these changes Mar 8, 2017 View changes

thobe requested changes Mar 30, 2017 View changes

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Mats-SX commented Mar 31, 2017

Mats-SX changed the title from Add the LIMIT CIP to Add the Subclauses CIP Mar 31, 2017

Mats-SX changed the title from Add the Subclauses CIP to Subclauses CIP May 5, 2017

Mats-SX commented Mar 6, 2017 •

edited

petraselmer requested changes Mar 6, 2017

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petraselmer approved these changes Mar 8, 2017

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thobe requested changes Mar 30, 2017

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