I currently can use the following promise notation as in wiki..
alasql.promise('SELECT * FROM XLS("mydata.xls") WHERE lastname LIKE "A%" and city = "London" GROUP BY name ')
.then(function(res){
console.log(res); // output depends on mydata.xls
}).catch(function(err){
console.log('Does the file exists? there was an error:', err);
});
What I need to do is run two queries and then merge the result data using custom js..
I could initialise two arrays before running the query and inside then block copy the query result to the array but is this the right way to handle such a situation.
Any help is sincerely appreciated.
Related
I've a query that uses difference function and I can't understand why it returns no data.
The query is:
SELECT
difference(FIRST(grid_power_counter)) as grid_power_consumed
FROM homesolar.origin.main GROUP BY time(15m)
If I remove the difference function it returns data:
SELECT
FIRST(grid_power_counter) as grid_power_consumed
FROM homesolar.origin.main GROUP BY time(15m)
Also, I can get results if I add a where time > now()-24h to the select with difference function.
I really can't understand that behavior. Can someone help me?
Q: My query would only work if I add the where filter to it. Why is that so?
Quoted from influxdb's Groupby time doc:
Basic GROUP BY time() queries require an InfluxQL function in the
SELECT clause and a time range in the WHERE clause.
I suspect your first DIFFERENCE query didn't work because it was missing the mandatory WHERE filter for the Groupby time(...) function.
The Group by time() clause could be returning no rows and hence not.
This could potentially be a github issue for the influx team as I think their query parser should be complaining to you about the missing where filter for Group by time.
References:
https://docs.influxdata.com/influxdb/v1.5/query_language/data_exploration/#the-group-by-clause
Following the question I asked: Build a dynamic query using neo4j client
I got an answer about how can I return value dynamically using string only.
When I'm trying to use the syntax to return multi values from the query it failed,
I tried the following query:
var resQuery2 = WebApiConfig.GraphClient.Cypher
.Match("(movie:Movie {title:{title}})")
.OptionalMatch("(movie)<-[r]-(person:Person)")
.WithParam("title", title)
.Return(() => Return.As<string>("movie, collect([person.name, head(split(lower(type(r)), '_')), r.roles])"));
I'm getting the following error:
The deserializer is running in single column mode, but the response
included multiple columns which indicates a projection instead. If
using the fluent Cypher interface, use the overload of Return that
takes a lambda or object instead of single string. (The overload with
a single string is for an identity, not raw query text: we can't map
the columns back out if you just supply raw query text.)
Is it possible to return multiple nodes using only strings?
We can't get an output like in the question you asked previously - this is due to the fact that you are asking for a Node (the movie) and a Collection of strings (the collect) and they have no common properties, or even styles of property.
Firstly, let's look at the painful way to do this:
var q = gc.Cypher
.Match("(movie:Movie)")
.OptionalMatch("(movie)<-[r]-(person:Person)")
.Return(() => Return.As<string>("{movie:movie, roles:collect([person.name, head(split(lower(type(r)), '_')), r.roles])}"));
var results = q.Results;
Here we take the query items (movie, r, person) and create a type with them the {} around the results, and cast that to a string.
This will give you a horrible string with the Node data around the movie and then a collection of the roles:
foreach (var m in results)
{
//This is going to be painful to navigate/use
dynamic d = JsonConvert.DeserializeObject<dynamic>(m);
Console.WriteLine(d.movie);
Console.WriteLine(d.roles);
}
You'd be a lot better off doing something like:
var q = gc.Cypher
.Match("(movie:Movie)")
.OptionalMatch("(movie)<-[r]-(person:Person)")
.Return(() => new
{
Movie = Return.As<Node<string>>("movie"),
Roles = Return.As<IEnumerable<string>>("collect([person.name, head(split(lower(type(r)), '_')), r.roles])")
});
var res = q.Results;
You could either JsonConvert.DeserializeObject<dynamic>() the Movie node, at your leisure, or write a strongly typed class.
In terms of a 'dynamic' object, I don't know how you were wanting to interact with the collect part of the return statement, if this doesn't help, you might need to update the question to show a usage expectation.
I'd like to make a cypher query that generates a specific json output. Part of this output includes an object with a dynamic amount of keys relative to the children of a parent node:
{
...
"parent_keystring" : {
child_node_one.name : child_node_one.foo
child_node_two.name : child_node_two.foo
child_node_three.name : child_node_three.foo
child_node_four.name : child_node_four.foo
child_node_five.name : child_node_five.foo
}
}
I've tried to create a cypher query but I do not believe I am close to achieving the desired output mentioned above:
MATCH (n)-[relone:SPECIFIC_RELATIONSHIP]->(child_node)
WHERE n.id='839930493049039430'
RETURN n.id AS id,
n.name AS name,
labels(n)[0] AS type,
{
COLLECT({
child.name : children.foo
}) AS rel_two_representation
} AS parent_keystring
I had planned for children.foo to be a count of how many occurrences of each particular relationship/child of the parent. Is there a way to make use of the reduce function? Where a report would generate based on analyzing the array proposed below? ie report would be a json object where each key is a distinct RELATIONSHIP and the property value would be the amount of times that relationship stems from the parent node?
Thank you greatly in advance for guidance you can offer.
I'm not sure that Cypher will let you use a variable to determine an object's key. Would using an Array work for you?
COLLECT([child.name, children.foo]) AS rel_two_representation
I think, Neo4j Server API output by itself should be considered as any database output (like MySQL). Even if it is possible to achieve, with default functionality, desired output - it is not natural way for database.
Probably you should look into creating your own server plugin. This allows you to implement any custom logic, with desired output.
I am parsing bitcoin blockchain, the whole idea is to build a node graph that looks like this (address)-[redeemed]->(tx)-[sent]->(address) so I can see how bitcoin addresses are related to each other. The problem is the execution time, sometimes it takes a few minutes to import just one transaction. Besides, some of these queries are too long, like few thousands of lines, and won't execute at all. I have read a few articles on how to optimize match queries, but found almost nothing about create and merge. I saw a few guys here recommending to use UNWIND and send as much data as possible as parameters, to make queries shorter, but I have no idea how to implement this in my query.
Here is example of my query: http://pastebin.com/9S0kLNey
You can try using the following simple query, passing the string parameters "hash", "time", "block", and "confs"; and a collection parameter named "data":
CREATE (tx:Tx {hash: {hash}, time: {time}, block: {block}, confirmations: {confs}})
FOREACH(x IN {data} |
MERGE (addr:Address {address: x.a})
CREATE (addr)-[:REDEEMED {value: x.v}]->(tx)
);
The values to use for the string parameters should be obvious.
Each "data" element would be a map containing an address ("a") and a value ("v"). For example, here is a snippet of the "data" collection that would correspond to the data in your sample query:
[
{a: "18oBAMgFaeFcZ5bziaYpUpsNCJ7G8EgH8g", v: "240"},
{a: "192W3HUVDyrp6ewvisHSijcx9f5ZoarrwX", v: "410"},
{a: "18tnEFy4usZvpMZLnjBFPjbmLKEzqPz958", v: "16.88"},
...
]
This query should run faster than your original sample, but I don't know how much faster.
i'm using riak to store json documents right now, and i want to sort them based on some attribute, let's say there's a key, i.e
{
"someAttribute": "whatever",
"order": 1
}
so i want to sort the documents based on the "order".
I am currently retrieving the documents in riak with the erlang interface. i can retrieve the document back as a string, but i dont' really know what to do after that. i'm thinking the map function just reduces the json document itself, and in the reduce function, i'd make a check to see whether the item i'm looking at has a higher "order" than the head of the rest of the list, and if so append to beginning, and then return a lists:reverse.
despite my ideas above i've had zero results after almost an entire day, i'm so confused with the erlang interface in riak. can someone provide insight on how to write this map/reduce function, or just how to parse the json document?
As far as I know, You do not have access to Input list in Map. You emit from Map a document as 1 element list.
Inputs (all the docs to handle as {Bucket, Key}) -> Map (handle single doc) -> Reduce (whole list emitted from Map).
Maps are executed per each doc on many nodes whereas Reduce is done once on so called coordinator node (the one where query was called).
Solution:
Define Inputs (as a list or bucket)
Retrieve Value in Map and emit whole doc or {Id, Val_to_sort_by)
Sort in Reduce (using regular list:keysort)
This is not a map reduce solution but you should check out Riak Search.
so i "solved" the problem using javascript, still can't do it using erlang.
here is my query
{"inputs":"test",
"query":[{"map":{"language":"javascript",
"source":"function(value, keyData, arg){ var data = Riak.mapValuesJson(value)[0]; var obj = {}; obj[data.order] = data; return [ obj ];}"}},
{"reduce":{"language":"javascript",
"source":"function(values, arg){ return [ values.reduce(function(acc, item){ for(var order in item){ acc[order] = item[order]; } return acc; }) ];}",
"keep":true}}
]
}
so in the map phase, all i do is create a new array, obj, with the key as the order, and the value as the data itself. so visually, the obj is like this
{"1":{"firstName":"John","order":1}
in the reduce phase, i'm just putting it in the accumulator, so basically that's the sort if you think about it, because when you're done, everything will be put in order for you. so i put 2 json documents for testing, one is above, the ohter is just firstName: Billie, order 2. and here is my result for the query above
[{"1":{"firstName":"John","order":1},"2":{"firstName":"Billie","order":2}}]
so it works! . but i still need to do this in ERLANG, any insights?