I've made a painting to illustrate my desired result:
painting of the result
I have a max timestamp that i pass to my backend and i want to return the newest versions of the Entities that have a timestamp that is less than the passed one.
The passed timestamp in my example is 180. I've kept the numbers low so that it is easier to visualize.
This is a combination of a horizontal and a vertical Query and i'm not sure how i can achieve that.
Any help would be appreciated!
It can be achieved with the following:
public List<Book> getBooksByMaxTimestamp(Date date) {
String formattedDate = simpleDateFormat.format(date);
System.out.println("Less than " + formattedDate);
AuditQuery maxRevisionNumberQuery = auditReader.createQuery().forRevisionsOfEntity(Book.class, true, false);
maxRevisionNumberQuery.add(AuditEntity.revisionProperty("timestamp").le(date.getTime()));
maxRevisionNumberQuery.addProjection(AuditEntity.revisionNumber().max());
int maxRevisionNumber = (int) maxRevisionNumberQuery.getSingleResult();
AuditQuery auditQuery = auditReader.createQuery().forEntitiesAtRevision(Book.class, maxRevisionNumber);
return auditQuery.getResultList();
}
First we get the max revision number that is in that range and after that we use that number to get the entities that we want.
Related
I've got a controller that first selects all data with status = 'CREATED' transferType = 'SOME_TYPE' and DATE_TIME between x and y, and then put all the data in the List<TransferEntity>
then i am going through each element in the list and updating status to 'CHECKED'
if (listOfTransfers.isNotEmpty()){
for(element in listOfTransfers){
element.status = "CHECKED"
repos.transfers.save(element)
}
}
entity itself is pretty straight forward with no relations to other tables
#Entity
#Table( name = "TRANSFERS")
class TransferEntity(
#Id
#Column(name = "Identifier", nullable = false)
var Identifier: String? = null,
#Column(name = "TRANS_DATE_TIME")
var transDateTime: LocalDateTime? = null,
#Column(name = "TRANS_TYPE", nullable = true, length = 255)
var transType: String? = null,
#Column(name = "STATUS")
var status: String = ""
)
i tried to experiment with indexes (oracle)
`CREATE INDEX TRANS_INDEX_1 ON TRANSFERS(STATUS)`
`CREATE INDEX TRANS_INDEX_2 ON TRANSFERS(TRANS_DATE_TIME)`
`CREATE INDEX TRANS_INDEX_3 ON TRANSFERS(TRANS_TYPE)`
or created them as one index
CREATE INDEX TRANS_INDEX_4 ON TRANSFERS(STATUS,TRANS_DATE_TIME,TRANS_TYPE)
but it wasnt a big difference
UPDATE
witn TRANS_INDEX_1 2 and 3 - 3192 elements were updateind in 5 minutes 30 sec
with TRANS_INDEX_4 - 3192 elements were updated in 5 minutes 30 sec
maybe there are different approaches to mass update elements inside the list or perhaps indexes are completely wrong and i dont understand them as much as i want it to.
UPDATE 2
technically saveAll() method works much faster but still I think there should be a room for improvement
saveAll() - 3192 elements were saved under 3minutes 21seconds
save() 3192 elements were save under 5minutes 30 seconds
You call save() each time you update an element. 1000 elements will create 1000 query calls to the database, you repeat too many calls to your DB and that's why your function is slow.
Instead, you could use saveAll() after you updated all the elements
as suggested below, we also have to config the batch_size properly to really do the trick
Indexes won't help in this situation since they benefit the select operation more than update or insert
Since you set the same value to all the elements of your list, you can make a batch update query :
Query q = entityManager.createQuery("update TransferEntity t set t.status = :value where t in (:list)");
q.setParameter("value", "CHECKED");
q.setParamter("list", listOfTransfers);
q.execute();
If you use ORACLE as backend be aware that in clause is limited to 1000 elements. Therefore you might have to split your list in buckets of 1000 elements and loop on this query for each bucket.
I'm new to Java so if this has already been answered somewhere else then I either don't know enough to search for the correct things or I just couldn't understand the answers.
So the question being:
I have a bunch of objects in a list:
try(Stream<String> logs = Files.lines(Paths.get(args))) {
return logs.map(LogLine::parseLine).collect(Collectors.toList());
}
And this is how the properties are added:
LogLine line = new LogLine();
line.setUri(matcher.group("uri"));
line.setrequestDuration(matcher.group("requestDuration"));
....
How do I sort logs so that I end up with list where objects with same "uri" are displayed only once with average requestDuration.
Example:
object1.uri = 'uri1', object1.requestDuration = 20;
object2.uri = 'uri2', object2.requestDuration = 30;
object3.uri = 'uri1', object3.requestDuration = 50;
Result:
object1.uri = 'uri1', 35;
object2.uri = 'uri2', 30;
Thanks in advance!
Take a look at Collectors.groupingBy and Collectors.averagingDouble. In your case, you could use them as follows:
Map<String, Double> result = logLines.stream()
.collect(Collectors.groupingBy(
LogLine::getUri,
TreeMap::new,
Collectors.averagingDouble(LogLine::getRequestDuration)));
The Collectors.groupingBy method does what you want. It is overloaded, so that you can specify the function that returns the key to group elements by, the factory that creates the returned map (I'm using TreeMap here, because you want the entries ordered by key, in this case the URI), and a downstream collector, which collects the elements that match the key returned by the first parameter.
If you want an Integer instead of a Double value for the averages, consider using Collectors.averagingInt.
This assumes LogLine has getUri() and getRequestDuration() methods.
I am having trouble with the following piece of code. Before I paste it, Let me give a bit of history on what should happen.
I have a model containing 2 fields of interest at the moment, which is the name of the order the customer placed, and the date at which he/she placed it. A pre-calculated date will be used to query the dateplaced field (and should only query the dates , and not the time). The query counts the amount of duplicates that occur in the MondayOrder field, and groups them together. Now , when I exclude the where clause which should query the dates, the query runs great. However, The goal of this query is to count the amount of orders for the following week based on the date the order has been placed.
List<string> returnlist = new List<string>();
DateTime dt = getNextWeekMondaysDate().Date;
switch (day)
{
case DayOfWeek.Monday:
{
var CountOrders =
from x in Data.EntityDB.Orders
group x by x.MondayOrder into m
let count = m.Count()
select new
{
MondayOrderItem = m.Key, Amount = count
};
foreach (var item in CountOrders)
{
returnlist.Add(item.MondayOrderItem + " : " +
item.Amount);
}
}
break;
The getNextWeekMondaysDate() method has an overload which I can use, where if I supply it a date, it will get the following Monday's date from the parameter given. The problem is though, LINQ does not accept queries such as the following:
var CountOrders =
from x in Data.EntityDB.Orders
where getNextWeekMondaysDate(x.DatePlaced.Value).Date == dt
group x by x.MondayOrder into m
let count = m.Count()
select new { MondayOrderItem = m.Key, Amount = count };
This is exactly what I must achieve. Is there any workaround for this situation?
UPDATE
Here is the exception I get when I try the 2nd query.
LINQ to Entities does not recognize the method 'System.DateTime getNextWeekMondaysDate(System.DateTime)' method, and this method cannot be translated into a store expression.
You cannot do this directly, as user-defined method calls cannot be translated to SQL by the EF query provider. The provider recognizes a limited set of .NET methods that can be translated to SQL and also a number of canonical functions as well. Anything that cannot be expressed using these methods only is off-limits unless you write your own query provider (which is only theoretically an option).
As a practical workaround, you can calculate an appropriate range for x.DatePlaced.Value in code before the query and then use specific DateTime values on the where clause.
As an intellectual exercise, note that this method is recognized by the query provider and can be used as part of the expression. So this abomination should work too:
var CountOrders =
from x in Data.EntityDB.Orders
where EntityFunctions.AddDays(
x.DatePlaced.Date.Value,
(9 - DateAndTime.DatePart(DateInterval.WeekDay, x.DatePlaced.Value)) % 7)
.Date == dt
group x by x.MondayOrder into m
let count = m.Count()
select new { MondayOrderItem = m.Key, Amount = count };
Linq to Entities doesn't know how to convert arbitrary C# methods into SQL - it's not possible in general.
So, you have to work with the methods it does understand.
In this case, you could do something like this:
DateTime weekBegin = CalculateWeekBegin( dt );
DateTime weekEnd = CalculateWeekEnd( dt );
var CountOrders =
from x in Data.EntityDB.Orders
where x.DatePlaced.Value >= weekBegin && x.DatePlaced.Value < weekEnd
group x by x.MondayOrder into m
let count = m.Count()
select new { MondayOrderItem = m.Key, Amount = count });
I have a program with multiple int variables where individual counts are added to the specific variable each time a set fail condition is encountered. I want the user to be able to track how many failures of each category they have encountered by a button click. I want to display the range on a datagridview in order from highest value integer down to lowest. I also need to display in the adjacent column the name of the test step that relates to the value. My plan was to use Array.sort to order the integers but i then lose track of their names so cant assign the adjacent string column. I tried using a hashtable but if i use the string as a key it sorts alphabetically not numerically and if i use the integer as a key i get duplicate entries which dont get added to the hash table. here is some of the examples i tried but they have the aforementioned problems. essentially i want to end with two arrays where the order matches the naming and value convention. FYI the variables were declared before this section of code, variables ending in x are the string name for the (non x) value of the integer.
Hashtable sorter = new Hashtable();
sorter[download] = downloadx;
sorter[power] = powerx;
sorter[phase] = phasex;
sorter[eeprom] = eepromx;
sorter[upulse] = upulsex;
sorter[vpulse] = vpulsex;
sorter[wpulse] = wpulsex;
sorter[volts] = voltsx;
sorter[current] = currentx;
sorter[ad] = adx;
sorter[comms] = commsx;
sorter[ntc] = ntcx;
sorter[prt] = prtx;
string list = "";
string[] names = new string[13];
foreach (DictionaryEntry child in sorter)
{
list += child.Value.ToString() + "z";
}
int[] ordered = new int[] { download, power, phase, eeprom, upulse, vpulse, wpulse, volts, current, ad, comms, ntc, prt };
Array.Sort(ordered);
Array.Reverse(ordered);
for (int i = 0; i < sorter.Count; i++)
{
int pos = list.IndexOf("z");
names[i] = list.Substring(0, pos);
list = list.Substring(pos + 1);
}
First question here so hope its not too longwinded.
Thanks
Use a Dictionary. And you can order it by the value : myDico.OrderBy(x => x.Value).Reverse(), the sort will be numerical descending. You just have to enumerate the result.
I hope I understand your need. Otherwise ignore me.
You want to be using a
Dictionary <string, int>
to store your numbers.I'm not clear on how you're displaying results at the end - do you have a grid or a list control?
You ask about usings. Which ones do you already have?
EDIT for .NET 2.0
There might be a more elegant solution, but you could implement the logic by putting your rows in a DataTable. Then you can make a DataView of that table and sort by whichever column you like, ascending or descending.
See http://msdn.microsoft.com/en-us/library/system.data.dataview(v=VS.80).aspx for example.
EDIT for .NET 3.5 and higher
As far as sorting a Dictionary by its values:
var sortedEntries = myDictionary.OrderBy(pair => pair.Value);
If you need the results to be a Dictionary, you can call .ToDictionary() on that. For reverse order, use .OrderByDescending(pair => pair.Value).
I am attempting to get unique values in a list of similar value distinguished only by a one element in a pipe delimited string... I keep getting at least one object must implement Icomparable. I don't understand why I keep getting that. I am able to groupBy that value... Why can't I find the max... I guess it is looking for something to compare it with. If I get the integer version will it stop yelling at me? This is the last time I am going to try using LINQ...
var queryResults = PatientList.GroupBy(x => x.Value.Split('|')[1]).Select(x => x.Max());
I know I can get the unique values some other way. I am just having a hard time figuring it out. In that List I know that the string with the highest value amongst its similar brethren is the one that I want to add to the list. How can I do that? I am totally drawing a blank because I have been trying to get this to work in linq for the last few days with no luck...
foreach (XmlNode node in nodeList)
{
XmlDocument xDoc = new XmlDocument();
xDoc.LoadXml(node.OuterXml);
string popPatInfo = xDoc.SelectSingleNode("./template/elements/element[#name=\"FirstName\"]").Attributes["value"].Value + ", " + xDoc.SelectSingleNode("./template/elements/element[#name=\"LastName\"]").Attributes["value"].Value + " | " + DateTime.Parse(xDoc.SelectSingleNode("./template/elements/element[#name=\"DateOfBirth\"]").Attributes["value"].Value.Split('T')[0]).ToString("dd-MMM-yyyy");
string patientInfo = xDoc.SelectSingleNode("./template/elements/element[#name=\"PatientId\"]").Attributes["value"].Value + "|" + xDoc.SelectSingleNode("./template/elements/element[#name=\"PopulationPatientID\"]").Attributes["enc"].Value;// +"|" + xDoc.SelectSingleNode("./template/elements/element[#name=\"AdminDate\"]").Attributes["value"].Value;
int enc = Int32.Parse(patientInfo.Split('|')[1]);
if (enc > temp)
{
lastEncounter.Add(enc, patientInfo);
temp = enc;
}
//lastEncounter.Add(Int32.Parse(patientInfo.Split('|')[1]));
PatientList.Add( new SelectListItem { Text = popPatInfo, Value = patientInfo });
}
I was thinking about using some kind of temp variable to find out what is the highest value and then add that string to the List. I am totally drawing a blank however...
Here I get the IDs in an anonymous type to make it readable.
var patientEncounters= from patient in PatientList
let PatientID=Int32.Parse(patient.Value.Split('|')[0])
let EncounterID=Int32.Parse(patient.Value.Split('|')[1])
select new { PatientID, EncounterID };
Then we group by UserID and get the last encounter
var lastEncounterForEachUser=from pe in patientEncounters
group pe by pe.PatientID into grouped
select new
{
PatientID=grouped.Key,
LastEncounterID=grouped.Max(g=>g.EncounterID)
};
Linq doesn't know how to compare 2 Patient objects, so it can't determine which one is the "greatest". You need to make the Patient class implement IComparable<Patient>, to define how Patient objects are compared.
// Compare objets by Id value
public int CompareTo(Patient other)
{
return this.Id.CompareTo(other.Id);
}
Another option is to use the MaxBy extension method available in Jon Skeet's MoreLinq project:
var queryResults = PatientList.GroupBy(x => x.Value.Split('|')[1])
.Select(x => x.MaxBy(p => p.Id));
EDIT: I assumed there was a Patient class, but reading your code again, I realize it's not the case. PatientList is actually a collection of SelectListItem, so you need to implement IComparable in that class.