[GitHub] [age] AadilBashir489 commented on issue #113: How to work with dynamic property
AadilBashir489 commented on issue #113:
URL: https://github.com/apache/age/issues/113#issuecomment-1597173727
I also the got exact same issue. I posted it on stackoverflow and got the
answer.
Answer:
You can later use the SET clause to insert the properties. Assuming that
{name: 'John Doe'} is the JSON provided by the user, the following code
demonstrates its usage:
`SELECT * FROM cypher('test', $$
CREATE (:Person)
$$) AS (res agtype);
res
-
(0 rows)
SELECT * FROM cypher('test', $$
MATCH (n:Person)
SET n = {name: 'John Doe'}
RETURN n
$$) AS (res agtype);
res
-
{"id": 1407374883553281, "label": "Person", "properties": {"name": "John
Doe"}}::vertex
(1 row)`
If you intend to incorporate user input, you'll need to use one of the
drivers available for AGE, such as the Python driver.
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[GitHub] [age] WendelLana commented on issue #981: Analyse MATCH clause performance (basic node finding)
WendelLana commented on issue #981:
URL: https://github.com/apache/age/issues/981#issuecomment-1597409977
### **Basic node finding**
Logic: each vertex and edge will have a unique identifier using the UUID
type of Postgres. UUIDs provide a stronger guarantee of uniqueness compared to
sequence generators. This eliminates the need for a separate table to store IDs
that have been deleted and simplifies the process of transferring data between
graphs and databases.
**Creating vertices and edges:**
Postgres provides a function called gen_random_uuid(), which we can utilize
to generate our unique identifiers. We will replace the existing logic with
this method.
Query:
```
CREATE ()-[]->()
```
Pseudo-code:
```
UUID previous_vertex, next_vertex;
FOR EACH node IN path
IF node.type == VERTEX AND previous_vertex != next_vertex THEN
previous_vertex = create_vertex() //generates UUID calling
gen_random_uuid() and creates vertex
ELSE IF node.type == EDGE
next_vertex = create_vertex()
create_edge(previous_vertex, next_vertex) //generates UUID and
creates edge
previous_vertex = next_vertex
ENDIF
NEXT node
```
- The loop iterates `n` times
- Inside the loop, the operations `create_vertex()` and `create_edge()` have
a constant time complexity
- Therefore, the overall time complexity of this pseudo code is O(n)
**Get all nodes**
```
MATCH (n)
RETURN n
```
This query will sequentially scan all vertices.
**Get all nodes with a label**
```
MATCH (movie:Movie)
RETURN movie.title
```
This query will use an index to efficiently scan vertices with the label
"movie".
**Related nodes**
```
MATCH (director {name: 'Oliver Stone'})--(movie)
RETURN movie.title
```
This query will sequentially scan all vertices, looking for nodes with the
property `name` equal to 'Oliver Stone'. It will then scan all edges to find
matches where the `start_id` or `end_id` correspond to the previously found
nodes.
**Match with labels**
```
MATCH (:Person {name: 'Oliver Stone'})--(movie:Movie)
RETURN movie.title
```
This query will use the index for "Person" to efficiently find nodes with
the name 'Oliver Stone'. Then, it will scan the edges to find connections
between those nodes and other vertices. The query ensures that the connected
vertices have the label "Movie" by utilizing an index for the "Movie" label.
Note: I have prioritized filtering properties such as name when creating the
query plan, but it is also possible to explore alternative search approaches.
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Re: Offset and out of bounds
You are looking at why it is called, right? In gdb you can use the *up *command
to look up the call stack to see what called something.
That function, btw, will get called by anything that needs to deserialize
agtype to agtype_value, even multiple times within a single agtype, due to
nested structures.
john
On Mon, Jun 12, 2023 at 12:08 PM Panagiotis Foliadis
wrote:
> Yes of course.
>
> When we run the basic select * from cypher
> ('test', $$ create (u) return u) as (u agtype), fill_agtype_value() is
> being called multiple times.
> There are times when its called with the base_addr having the value
> "idlabelproperties" and the offset
> helps breaking down this string to fill correctly the json object that
> will be return to the client. But there
> are cases that when the fill_agtype_value() is called, for example when
> the node we are creating has
> no label, that the offset is 32, which is larger than the length of the
> base_addr. Running gdb with
> fill_agtype_value() as a breaking point would make it easier to understand
> what im trying to say.
>
>
> Από: John Gemignani
> Στάλθηκε: Δευτέρα, 12 Ιουνίου 2023 10:03 μμ
> Προς: dev@age.apache.org
> Θέμα: Re: Offset and out of bounds
>
> Could you give some example cases?
>
> john
>
> On Mon, Jun 12, 2023 at 11:12 AM Panagiotis Foliadis <
> pfolia...@hotmail.com>
> wrote:
>
> > Hey all,
> >
> > I'm having a hard time understanding the offset functionality in
> > fill_agtype_value().
> > There are many times when this function is called that the offset is
> > greater than the
> > length of the base_addr resulting in fetching a value from out of
> bounds.
> > How do the
> > out-of-bounds values get initialized and what are we trying to achieve by
> > having the offset
> > reach for the out-of-bounds values?
> >
>
Απ: Offset and out of bounds
Ive figured out everything that I needed thank you for your response!
Από: John Gemignani
Στάλθηκε: Δευτέρα, 19 Ιουνίου 2023 9:25 μμ
Προς: dev@age.apache.org
Θέμα: Re: Offset and out of bounds
You are looking at why it is called, right? In gdb you can use the *up *command
to look up the call stack to see what called something.
That function, btw, will get called by anything that needs to deserialize
agtype to agtype_value, even multiple times within a single agtype, due to
nested structures.
john
On Mon, Jun 12, 2023 at 12:08 PM Panagiotis Foliadis
wrote:
> Yes of course.
>
> When we run the basic select * from cypher
> ('test', $$ create (u) return u) as (u agtype), fill_agtype_value() is
> being called multiple times.
> There are times when its called with the base_addr having the value
> "idlabelproperties" and the offset
> helps breaking down this string to fill correctly the json object that
> will be return to the client. But there
> are cases that when the fill_agtype_value() is called, for example when
> the node we are creating has
> no label, that the offset is 32, which is larger than the length of the
> base_addr. Running gdb with
> fill_agtype_value() as a breaking point would make it easier to understand
> what im trying to say.
>
>
> Από: John Gemignani
> Στάλθηκε: Δευτέρα, 12 Ιουνίου 2023 10:03 μμ
> Προς: dev@age.apache.org
> Θέμα: Re: Offset and out of bounds
>
> Could you give some example cases?
>
> john
>
> On Mon, Jun 12, 2023 at 11:12 AM Panagiotis Foliadis <
> pfolia...@hotmail.com>
> wrote:
>
> > Hey all,
> >
> > I'm having a hard time understanding the offset functionality in
> > fill_agtype_value().
> > There are many times when this function is called that the offset is
> > greater than the
> > length of the base_addr resulting in fetching a value from out of
> bounds.
> > How do the
> > out-of-bounds values get initialized and what are we trying to achieve by
> > having the offset
> > reach for the out-of-bounds values?
> >
>
