I´m new to Neo4j, and want to implement a service that makes use of it.
I´ve read the docs and searched for it, however I still didn´t get an answer to this simple question:
How do I specify which database to query in a Neo4j query?
E.g. I connected to bolt://localhost:7687, and have three databases in there: system, neo4j, and mydb. The neo4j database is the standard.
When I open the Neo4j browser and do a query such as MATCH (n) RETURN n, it automatically assumes that I want to query the standard DB which is called neo4j. However, I want to query another one, mydb.
My output when I query aforementioned query says
{
"query": {
"text": "match (n) return n",
"parameters": {}
},
"queryType": "r",
"counters": {
"_stats": {
"nodesCreated": 0,
"nodesDeleted": 0,
"relationshipsCreated": 0,
"relationshipsDeleted": 0,
"propertiesSet": 0,
"labelsAdded": 0,
"labelsRemoved": 0,
"indexesAdded": 0,
"indexesRemoved": 0,
"constraintsAdded": 0,
"constraintsRemoved": 0
},
"_systemUpdates": 0
},
"updateStatistics": {
"_stats": {
"nodesCreated": 0,
"nodesDeleted": 0,
"relationshipsCreated": 0,
"relationshipsDeleted": 0,
"propertiesSet": 0,
"labelsAdded": 0,
"labelsRemoved": 0,
"indexesAdded": 0,
"indexesRemoved": 0,
"constraintsAdded": 0,
"constraintsRemoved": 0
},
"_systemUpdates": 0
},
"plan": false,
"profile": false,
"notifications": [],
"server": {
"address": "localhost:7687",
"version": "Neo4j/4.4.5",
"agent": "Neo4j/4.4.5",
"protocolVersion": 4.4
},
"resultConsumedAfter": {
"low": 2,
"high": 0
},
"resultAvailableAfter": {
"low": 8,
"high": 0
},
"database": {
"name": "neo4j"
}
}
In the last JSON value is the proof that the query was executed on database neo4j.
What do I have to add to my queries to instead query another database in the same DBMS?
You can change/specify the database using the following options.
From the Neo4j Browser, you can select the database in the sidebar.
In Cypher syntax, the use command lets you choose different databases.
:use mydb.
If you connect to Neo4j through an Application driver, you can specify the database while creating the session object.
For example, if you are using the Python driver:
from neo4j import GraphDatabase
driver = GraphDatabase.driver(uri, auth=(user, password))
session = driver.session(database="mydb")
Specify the default database in a system-wide manner by modifying the config_dbms.default_database value in the the neo4j.conf file.
I am using libmosquitto and the parson library in a C application running on my IoT device for doing stuff with MQTT and parsing JSON.
When I publish a message to my device using the mosquitto_pub command on a Linux terminal as follows :
mosquitto_pub -t "mytopic/test" -u "admin" -P "admin" -h 192.168.5.100 -m "{"value1": 1, "value2": 2, "value3": 3}"
I am succesfully receiving the message on the device as I am subscribed to it, however, I cannot parse the values at all using json_object_dotget_value
JSON_Value* root_value = json_parse_string(payload);
JSON_Object* root_object = json_value_get_object(root_value);
JSON_Value* value1 = json_object_dotget_value(root_object, "value1");
JSON_Value* value2 = json_object_dotget_value(root_object, "value2");
JSON_Value* value3 = json_object_dotget_value(root_object, "value3");
The values returned are NULL.
I know that i'm leaving out lots of code here. However, the problem is not on the receiving end, because when another application in Python publishes this message, the parsing works fine.
There is something wrong with my mosquitto_pub command, but I can't see it.
I'd appreciate any help. Thanks.
Per your comment, your program is fine.
In the invocation, you may have to escape the " in the argument to your sender program (or use single quotes)
With -m "{"value1": 1, "value2": 2, "value3": 3}", the args [as the program sees them] are:
-m
{value1: 1, value2: 2, value3: 3}
Notice that the " got stripped around (e.g.) value1 and json needs them.
So, change to -m '{"value1": 1, "value2": 2, "value3": 3}' and the args become:
-m
{"value1": 1, "value2": 2, "value3": 3}
I have a task in which I have to calculate the time taken by each step, for example if we are clicking on a link, how much time is taken to load the page and next step to be executed.
I want fail the test case if time taken is more then say 2 seconds.
I have tried using protractor-perf and it gives me the readings below and these don't help, or I am not able to read anything correctly.
{ Styles: 0,
Javascript: 0,
numAnimationFrames: 4625,
numFramesSentToScreen: 4625,
droppedFrameCount: 417,
meanFrameTime_raf: 18.242160830084256,
framesPerSec_raf: 54.81806729556069,
connectEnd: 1524251882749,
connectStart: 1524251882459,
domComplete: 1524251916054,
domContentLoadedEventEnd: 1524251916053,
domContentLoadedEventStart: 1524251916050,
domInteractive: 1524251916050,
domLoading: 1524251883038,
domainLookupEnd: 1524251882459,
domainLookupStart: 1524251882459,
fetchStart: 1524251882458,
firstPaint: 33600.99983215332,
loadEventEnd: 1524251916055,
loadEventStart: 1524251916054,
navigationStart: 1524251882456,
redirectEnd: 0,
redirectStart: 0,
requestStart: 1524251882749,
responseEnd: 1524251883592,
responseStart: 1524251883032,
secureConnectionStart: 0,
unloadEventEnd: 0,
unloadEventStart: 0,
loadTime: 33597,
domReadyTime: 4,
readyStart: 2,
redirectTime: 0,
appcacheTime: 1,
unloadEventTime: 0,
domainLookupTime: 0,
connectTime: 290,
requestTime: 843,
initDomTreeTime: 32458,
loadEventTime: 1 }
I have also tried using log-timestamp and I can print the timestamp to log but cannot get the difference to use it in a variable and fail the test case.
I get the output like this in the log:
[2018-04-20T19:19:13.325Z] Start
[2018-04-20T19:19:14.046Z] Step1
[2018-04-20T19:19:47.667Z] Step2
[2018-04-20T19:19:50.304Z] Step3
[2018-04-20T19:19:52.111Z] Step4
[2018-04-20T19:19:57.344Z] Step5
[2018-04-20T19:19:59.029Z] Step6
I would really appreciate your help guys, this has wasted a lot my time.
I am trying to use zeppelin to plot a realtime graph. I have doing a sentiment analysis on tweets on per minute . I am able to query statically and plot a graph. But i would like this to be done dynamically. I am new to zeppelin and do not have much knowledge about angularJS. What should be the correct approach to this problem?
val final_score=uni_join.map{case((year,month,day,hour,minutes),(tweet_count,sentiment))=>(year, month, day, hour, minutes(sentiment/tweet_count).ceil)}
final_score.saveToCassandra("twitter", "score",writeConf = WriteConf(ttl = TTLOption.constant(1000)))
final_score.foreachRDD(score => {
val rowRDD =score.map{case(year,month,day,hour,minutes,sentiment) =>(year,month,day,hour,minutes,sentiment) }
val tempDF = sqlContext.createDataFrame(rowRDD)
z.angularBindGlobal("stream", parsed) //to bind parsed to stream.
tempDF.registerTempTable("realTimeTable")
})
Doing a query on the above table , i am able to get the graph. But i would like to dynamically update the graph every minute in order to keep in sync with the sentiment score .
Thanks prior.
[update] the angular part for the zeppelin notebook are as follows:
%angular
<div id="graph" style="height: 100%; width: 100%">
<canvas id="myChart" width="400" height="400"></canvas>
<div id="legendDiv"></div>
</div>
<script>
function initMap() {
var colorList = ["#fde577", "#ff6c40", "#c72a40", "#520833", "#a88399"]
var el = angular.element($('#stream'));
console.log("El is "+el) //returns el as object
angular.element(el).ready(function() {
console.log('Hello')
window.locationWatcher =el.$scope.$watch('stream', function(new, old){
console.log('changed');}, true)})
</script>
But running this code keeps returning the following error.
vendor.js:29 jQuery.Deferred exception: Cannot read property '$watch' of undefined TypeError: Cannot read property '$watch' of undefined
The spark version that i am using is 1.6
And Zeppelin is 0.6
spark-highcharts since version 0.6.3 support Spark Structured Streaming.
For a structuredDataFrame after aggregation, with the following code in one Zeppelin paragraph. The OutputMode can be either append or complete depends how the structureDataFrame is aggregated.
import com.knockdata.spark.highcharts._
import com.knockdata.spark.highcharts.model._
val query = highcharts(
structuredDataFrame.seriesCol("country")
.series("x" -> "year", "y" -> "stockpile")
.orderBy(col("year")), z, "append")
And the following code in the next paragraph. The chart in this paragraph will be updated when there are new data coming to the structureDataFrame.
StreamingChart(z)
Run following code to stop update the chart.
query.stop()
Here is the example generate structureDataFrame.
spark.conf.set("spark.sql.streaming.checkpointLocation","/usr/zeppelin/checkpoint")
case class NuclearStockpile(country: String, stockpile: Int, year: Int)
val USA = Seq(0, 0, 0, 0, 0, 6, 11, 32, 110, 235, 369, 640,
1005, 1436, 2063, 3057, 4618, 6444, 9822, 15468, 20434, 24126,
27387, 29459, 31056, 31982, 32040, 31233, 29224, 27342, 26662,
26956, 27912, 28999, 28965, 27826, 25579, 25722, 24826, 24605,
24304, 23464, 23708, 24099, 24357, 24237, 24401, 24344, 23586,
22380, 21004, 17287, 14747, 13076, 12555, 12144, 11009, 10950,
10871, 10824, 10577, 10527, 10475, 10421, 10358, 10295, 10104).
zip(1940 to 2006).map(p => NuclearStockpile("USA", p._1, p._2))
val USSR = Seq(0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
5, 25, 50, 120, 150, 200, 426, 660, 869, 1060, 1605, 2471, 3322,
4238, 5221, 6129, 7089, 8339, 9399, 10538, 11643, 13092, 14478,
15915, 17385, 19055, 21205, 23044, 25393, 27935, 30062, 32049,
33952, 35804, 37431, 39197, 45000, 43000, 41000, 39000, 37000,
35000, 33000, 31000, 29000, 27000, 25000, 24000, 23000, 22000,
21000, 20000, 19000, 18000, 18000, 17000, 16000).
zip(1940 to 2006).map(p => NuclearStockpile("USSR/Russia", p._1, p._2))
input.addData(USA.take(30) ++ USSR.take(30))
val structureDataFrame = input.toDF
And the following code can be simulate to update the chart. The chart will be updated when the following code run.
input.addData(USA.drop(30) ++ USSR.drop(30))
NOTE: The example using Zeppelin 0.6.2 and Spark 2.0
NOTE: Please check the highcharts license for commercial usage
I'm retrieving multiple appointments via AppointmentCalendar.FindAppointmentsAsync. I'm evaluating the Recurrence.RecurrenceType and noticed an unexpected value of 1 for master appointments of a series. I expect the Recurrence.RecurrenceType to be 0 (Master) but instead it is 1 (Instance).
(Note: I added AppointmentProperties.Recurrence to FindAppointmentsOptions.FetchProperties that is passed to GetAppointmentsAsync, so the Recurrence data should be fetched propertly.)
To double check I retrieved the respective master appointment via GetAppointmentAsync (instead of FindAppointmentsAsync) using its LocalId - and here the RecurrenceType is correctly set to 0.
Here is demo output for a test appointment series:
Data gotten by FindAppointmentsAsync (Instance??):
"Recurrence": {
"Unit": 0,
"Occurrences": 16,
"Month": 1,
"Interval": 1,
"DaysOfWeek": 0,
"Day": 1,
"WeekOfMonth": 0,
"Until": "2016-09-29T02:00:00+02:00",
"TimeZone": "Europe/Budapest",
"RecurrenceType": 1,
"CalendarIdentifier": "GregorianCalendar"
},
"StartTime": "2016-09-14T19:00:00+02:00",
"OriginalStartTime": "2016-09-14T19:00:00+02:00",
Data gotten by GetAppointmentAsync for the same appointment (Master):
"Recurrence": {
"Unit": 0,
"Occurrences": 16,
"Month": 1,
"Interval": 1,
"DaysOfWeek": 0,
"Day": 1,
"WeekOfMonth": 0,
"Until": "2016-09-29T02:00:00+02:00",
"TimeZone": "Europe/Budapest",
"RecurrenceType": 0,
"CalendarIdentifier": "GregorianCalendar"
},
"StartTime": "2016-09-14T19:00:00+02:00",
"OriginalStartTime": null,
Notice the difference in RecurrenceType. Also note that OriginalStartTime is set to null for the master gotten by GetAppointmentAsync but has a value for the appointment gotten by FindAppointmentsAsync.
You can also see that the StartTime for the master appointment is the start time set for the alleged Instance (which in reality is the master).
Shouldn't FindAppointmentsAsync return a master as the first element of a series, instead of an instance?
(SDK: 10.0.14393.0, Anniversary)
Code to explicitly find such a master/instance situation for a given calendar:
var appointmentsCurrent = await calendar.FindAppointmentsAsync(DateTimeOffset.Now, TimeSpan.FromDays(365), findAppointmentOptions);
foreach(var a in appointmentsCurrent)
{
var a2 = await calendar.GetAppointmentAsync(a.LocalId);
if (a2.Recurrence?.RecurrenceType == RecurrenceType.Master &&
a2.StartTime == a.StartTime &&
a.Recurrence?.RecurrenceType == RecurrenceType.Instance &&
a.OriginalStartTime == a2.StartTime)
{
Debug.WriteLine("Gotcha!");
}
}
I tested above code on my side. If you get the count of the appointments which are got from FindAppontmentsAsync by the following code:var count=appointmentsCurrent.Count;, you will find it does return the count of the appointment instances, not the count of master appointments. So the FindAppontmentsAsync method got all instances of the appointments not master appointments. This is the reason why the RecurrenceType is instance.
It seems like we can get one master appointment by method GetAppointmentAsync as you mentioned above, so I suppose this may not block you.
If you think this is not a good design for this API or you require a API for finding all the master appointments in one calendar, you can submit your ideas to the windows 10 feedback tool or the user voice site.