I am trying to use a DynamoDB table to store this data:
DartsPlayerInsultTable
CustomerId String
PlayerId String
PlayerInsult String
Using the method (concept, not code) described here:
https://java.awsblog.com/post/Tx3GYZEVGO924K4/The-DynamoDBMapper-Local-Secondary-Indexes-and-You
here:
http://mobile.awsblog.com/post/TxTCW7KW8BGZAF/Amazon-DynamoDB-on-Mobile-Part-4-Local-Secondary-Indexes
and here:
http://labs.journwe.com/2013/12/15/dynamodb-secondary-indexes/comment-page-1/#comment-116
I want to have multiple insult records per customer-player.
CustomerId is my Hash Key
PlayerId is my Range Key
and I a trying to use PlayerInsult in a key so that
a second PlayerInsult value inserts a second record
rather than replacing the existing one.
Have tried both Global and Secondary indexes for this,
but if I try to add a row with a new insult, it still
replaces the insult with the same customer-player key
rather than adding a new one.
Any suggestions on the best approach to use for this is
DynanoDB? Do I need to create a hybrid column for a range-key?
Trying to keep this simple...
class func createDartsPlayerInsultTable() -> BFTask {
let dynamoDB = AWSDynamoDB.defaultDynamoDB()
let hashKeyAttributeDefinition = AWSDynamoDBAttributeDefinition()
hashKeyAttributeDefinition.attributeName = "CustomerId"
hashKeyAttributeDefinition.attributeType = AWSDynamoDBScalarAttributeType.S
let hashKeySchemaElement = AWSDynamoDBKeySchemaElement()
hashKeySchemaElement.attributeName = "CustomerId"
hashKeySchemaElement.keyType = AWSDynamoDBKeyType.Hash
let rangeKeyAttributeDefinition = AWSDynamoDBAttributeDefinition()
rangeKeyAttributeDefinition.attributeName = "PlayerId"
rangeKeyAttributeDefinition.attributeType = AWSDynamoDBScalarAttributeType.S
let rangeKeySchemaElement = AWSDynamoDBKeySchemaElement()
rangeKeySchemaElement.attributeName = "PlayerId"
rangeKeySchemaElement.keyType = AWSDynamoDBKeyType.Range
/*
let indexRangeKeyAttributeDefinition = AWSDynamoDBAttributeDefinition()
indexRangeKeyAttributeDefinition.attributeName = "PlayerInsult"
indexRangeKeyAttributeDefinition.attributeType = AWSDynamoDBScalarAttributeType.S
let rangeKeySchemaElement = AWSDynamoDBKeySchemaElement()
rangeKeySchemaElement.attributeName = "PlayerId"
rangeKeySchemaElement.keyType = AWSDynamoDBKeyType.Range
let indexRangeKeyElement = AWSDynamoDBKeySchemaElement()
indexRangeKeyElement.attributeName = "PlayerInsult"
indexRangeKeyElement.keyType = AWSDynamoDBIndexRangeKeyType.
*/
//Add non-key attributes
let playerInsultAttrDef = AWSDynamoDBAttributeDefinition()
playerInsultAttrDef.attributeName = "PlayerInsult"
playerInsultAttrDef.attributeType = AWSDynamoDBScalarAttributeType.S
let provisionedThroughput = AWSDynamoDBProvisionedThroughput()
provisionedThroughput.readCapacityUnits = 5
provisionedThroughput.writeCapacityUnits = 5
// CREATE GLOBAL SECONDARY INDEX
/*
let gsi = AWSDynamoDBGlobalSecondaryIndex()
let gsiArray = NSMutableArray()
let gsiHashKeySchema = AWSDynamoDBKeySchemaElement()
gsiHashKeySchema.attributeName = "PlayerId"
gsiHashKeySchema.keyType = AWSDynamoDBKeyType.Hash
let gsiRangeKeySchema = AWSDynamoDBKeySchemaElement()
gsiRangeKeySchema.attributeName = "PlayerInsult"
gsiRangeKeySchema.keyType = AWSDynamoDBKeyType.Range
let gsiProjection = AWSDynamoDBProjection()
gsiProjection.projectionType = AWSDynamoDBProjectionType.All;
gsi.keySchema = [gsiHashKeySchema,gsiRangeKeySchema];
gsi.indexName = "PlayerInsult";
gsi.projection = gsiProjection;
gsi.provisionedThroughput = provisionedThroughput;
gsiArray .addObject(gsi)
*/
// CREATE LOCAL SECONDARY INDEX
let lsi = AWSDynamoDBLocalSecondaryIndex()
let lsiArray = NSMutableArray()
let lsiHashKeySchema = AWSDynamoDBKeySchemaElement()
lsiHashKeySchema.attributeName = "CustomerId"
lsiHashKeySchema.keyType = AWSDynamoDBKeyType.Hash
let lsiRangeKeySchema = AWSDynamoDBKeySchemaElement()
lsiRangeKeySchema.attributeName = "PlayerInsult"
lsiRangeKeySchema.keyType = AWSDynamoDBKeyType.Range
let lsiProjection = AWSDynamoDBProjection()
lsiProjection.projectionType = AWSDynamoDBProjectionType.All;
lsi.keySchema = [lsiHashKeySchema,lsiRangeKeySchema];
lsi.indexName = "PlayerInsult";
lsi.projection = lsiProjection;
//lsi.provisionedThroughput = provisionedThroughput;
lsiArray .addObject(lsi)
//Create TableInput
let createTableInput = AWSDynamoDBCreateTableInput()
createTableInput.tableName = DartsPlayerInsultTableName;
createTableInput.attributeDefinitions = [hashKeyAttributeDefinition, rangeKeyAttributeDefinition, playerInsultAttrDef]
//createTableInput.attributeDefinitions = [hashKeyAttributeDefinition, rangeKeyAttributeDefinition]
createTableInput.keySchema = [hashKeySchemaElement, rangeKeySchemaElement]
createTableInput.provisionedThroughput = provisionedThroughput
//createTableInput.globalSecondaryIndexes = gsiArray as [AnyObject]
createTableInput.localSecondaryIndexes = lsiArray as [AnyObject]
return dynamoDB.createTable(createTableInput).continueWithSuccessBlock({ (var task:BFTask!) -> AnyObject! in
if ((task.result) != nil) {
// Wait for up to 4 minutes until the table becomes ACTIVE.
let describeTableInput = AWSDynamoDBDescribeTableInput()
describeTableInput.tableName = DartsPlayerInsultTableName;
task = dynamoDB.describeTable(describeTableInput)
for var i = 0; i < 16; i++ {
task = task.continueWithSuccessBlock({ (task:BFTask!) -> AnyObject! in
let describeTableOutput:AWSDynamoDBDescribeTableOutput = task.result as! AWSDynamoDBDescribeTableOutput
let tableStatus = describeTableOutput.table.tableStatus
if tableStatus == AWSDynamoDBTableStatus.Active {
return task
}
sleep(15)
return dynamoDB .describeTable(describeTableInput)
})
}
}
return task
})
}
Putting this as an answer and not another comment in case it gets long...
It sounds like the average user's insults might fit into a single record. With the disclaimer that I know absolutely nothing about swift, this might at least be something relatively simple. Keep your customer and player keys. Before you persist the insults, turn the whole list into one big string using whatever version of join("|") swift has. When you fetch the record, do a split("|") to get your list back. (Just be a little judicious with your choice of separators, I'm only using "|" as an example, you don't want to choose something that might appear in an insult...)
There's going to be that one user with enough insults to take you over the 400kb object limit. Set a max list size constant in your code -- when you turn your lists into strings to persist them to dynamo, check the player's list length against that limit. If you exceed it, break your list into chunks of that size and use hash and range keys like ("foo", "bar"), ("foo", "bar1"), ("foo", "bar2"), etc. Yes, the first one does not have a bucket number at the end...
When you query for the data, just do a straight query first and assume you'll be in the good case (just "foo" and "bar", no other buckets). When you unpack that first list, check its length. If it's equal to your max list size constant, you know that you got a "bad" user and need to do a range query. That second one can use the hash key "foo" and the range "bar" to "bar9999". You will fetch back all those buckets with that range query. Unpack and concatenate all the lists.
This is a little gory, but it should also ultimately be straight ahead to code up. Hopefully it's still simple enough to hook into the patterns you mentioned.
What I decided to do was make a conventional dynamodb table with just one hash key, but the new hash key is a combined string of:
CustomerId + "|" + PlayerId
It is not too hard to maintain synchrony between players and insults tables because once a player is inserted into the player table, modifying the player name results in a new row being inserted. Thus, insults do not need to be modified if the player name changes. You only need to cleanup insults if a player is deleted.
This update behavior is just the way dynamodb works if you make Player name a hash key, which I did to insure they were unique.
Related
I am working on a simple database procedure in Kotlin using Room, and I can't explain why the process is so slow, mostly on the Android Studio emulator.
The table I am working on is this:
#Entity(tableName = "folders_items_table", indices = arrayOf(Index(value = ["folder_name"]), Index(value = ["item_id"])))
data class FoldersItems(
#PrimaryKey(autoGenerate = true)
var uid: Long = 0L,
#ColumnInfo(name = "folder_name")
var folder_name: String = "",
#ColumnInfo(name = "item_id")
var item_id: String = ""
)
And what I am just trying to do is this: checking if a combination folder/item is already present, insert a new record. If not, ignore it. on the emulator, it takes up to 7-8 seconds to insert 100 records. On a real device, it is much faster, but still, it takes around 3-4 seconds which is not acceptable for just 100 records. It looks like the "insert" query is particularly slow.
Here is the procedure that makes what I have just described (inside a coroutine):
val vsmFoldersItems = FoldersItems()
items.forEach{
val itmCk = database.checkFolderItem(item.folder_name, it)
if (itmCk == 0L) {
val newFolderItemHere = vsmFoldersItems.copy(
folder_name = item.folder_name,
item_id = it
)
database.insertFolderItems(newFolderItemHere)
}
}
the variable "items" is an array of Strings.
Here is the DAO definitions of the above-called functions:
#Query("SELECT uid FROM folders_items_table WHERE folder_name = :folder AND item_id = :item")
fun checkFolderItem(folder: String, item: String): Long
#Insert
suspend fun insertFolderItems(item: FoldersItems)
Placing the loop inside a single transaction should significantly reduce the time taken.
The reason is that each transaction (by default each SQL statement that makes a change to the database) will result in a disk write. So that's 100 disk writes for your loop.
If you begin a transaction before the loop and then set the transaction successful when the loop is completed and then end the transaction a single disk write is required.
What I am unsure of is exactly how to do this when using a suspended function (not that familiar with Kotlin).
As such I'd suggest either dropping the suspend or having another Dao for use within loops.
Then have something like :-
val vsmFoldersItems = FoldersItems()
your_RoomDatabase.beginTransaction()
items.forEach{
val itmCk = database.checkFolderItem(item.folder_name, it)
if (itmCk == 0L) {
val newFolderItemHere = vsmFoldersItems.copy(
folder_name = item.folder_name,
item_id = it
)
database.insertFolderItems(newFolderItemHere)
}
}
your_RoomDatabase.setTransactionSuccessful() //<<<<<<< IF NOT set then ALL updates will be rolled back
your_RoomDatabase.endTransaction()
You may wish to refer to:-
https://developer.android.com/reference/androidx/room/RoomDatabase
You may wish to especially refer to runInTransaction
Is there a better way of doing this seems mundan to be retyping every var I think though automaper is to much for such a record however.
It works fine but I cant help but think could be neater I want to copy people cache also into the poi record
public POI FindPersonOrVessel(POI poiRecord ,int CaseId)
{
//each person that will be saved here will have a urn unique record number
var findPersoninCache = _context.PeopleCache.Where(w => w.PersonUrn == poiRecord.Id);
{
PeopleCache peopleCache = new PeopleCache();
peopleCache.FirstName = poiRecord.FirstName;
peopleCache.LastName = poiRecord.LastName;
peopleCache.DOB = poiRecord.DOB;
peopleCache.Age = poiRecord.Age;
peopleCache.Alias = peopleCache.Alias;
peopleCache.MISObjectId = CaseId;
peopleCache.FacialFeatures = poiRecord.FacialFeatures;
peopleCache.PersonUrn = poiRecord.Id;
_context.PeopleCache.Add(peopleCache);
_context.SaveChanges();
_toast.AddSuccessToastMessage("Saved Poi to Cache");
}
}
You could place the copy function into it's own method (passing into it whatever objects u need), then call that method in findpersonorvessel. On the surface its neat, the "messy details" are encapsulated.
I want to create multiple records at the same time using client script. This is what I'm doing:
var ceateDatasource = app.datasources.Reservation.modes.create;
var newItem = ceateDatasource.item;
newItem.User = user; //'eric'
newItem.Description = description; //'000'
newItem.Location_Lab_fk = lab.value.Id; //'T'
newItem.Area_fk = area.value.Id; //'L'
newItem.Equipment_fk = equipment.value.Id; //'S'
for(var i = 0 ; i < 3; i ++) {
newItem.Start_Date = startDate;
newItem.Start_Hours = '03';
newItem.Start_Minutes = '00';
newItem.End_Date = startDate;
newItem.End_Hours = '23';
newItem.End_Minutes = '30';
// Create the new item
ceateDatasource.createItem();
}
But the result I'm getting is this one:
The three records are created but the only the first one has data. The other two records have empty values on their fields. How can I achieve this?
Thanks.
Update(2019-3-27):
I was able to make it work by putting everything inside the for loop block. However, I have another question.
Is there any method like the below sample code?
var recordData = [Data1, Data2, Data3]
var ceateDatasource;
var newItem = new Array(recordData.length) ;
for(var i = 0 ; i < recordData.length; i ++) {
ceateDatasource = app.datasources.Reservation.modes.create;
newItem[i] = ceateDatasource.item;
newItem[i].User = recordData[i].user;
newItem[i].Description = recordData[i].Description;
newItem[i].Location_Lab_fk = recordData[i].Location_Lab_fk;
newItem[i].Area_fk = recordData[i].Area_fk;
newItem[i].Equipment_fk = recordData[i].Equipment_fk;
newItem[i].Start_Date = recordData[i].Start_Date;
newItem[i].Start_Hours = recordData[i].Start_Hours;
newItem[i].Start_Minutes = recordData[i].Start_Minutes;
newItem[i].End_Date = recordData[i].End_Date;
newItem[i].End_Hours = recordData[i].End_Hours;
newItem[i].End_Minutes = recordData[i].End_Minutes;
}
// Create the new item
ceateDatasource.createItem();
First, it prepares an array 'newItem' and only calls 'ceateDatasource.createItem()' one time to save all new records(or items).
I try to use this method, but it only saves the last record 'newItem[3]'.
I need to write a callback function in 'ceateDatasource.createItem()' but Google App Maker always show a warning "Don't make functions within a loop". So, are there any methods to call 'createItem()' one time to save several records? Or are there some functions like 'array.push' which can be used?
Thanks.
As per AppMaker's official documentation:
A create datasource is a datasource used to create items in a particular data source. Its item property is always populated by a draft item which can be bound to or set programmatically.
What you are trying to do is create three items off the same draft item. That why you see the result you get. If you want to create multiple items, you need to create a draft item for each one, hence all you need to do is put all your code inside the for loop.
for(var i = 0 ; i < 3; i ++) {
var ceateDatasource = app.datasources.Reservation.modes.create;
var newItem = ceateDatasource.item;
newItem.User = user; //'eric'
newItem.Description = description; //'000'
newItem.Location_Lab_fk = lab.value.Id; //'T'
newItem.Area_fk = area.value.Id; //'L'
newItem.Equipment_fk = equipment.value.Id; //'S'
newItem.Start_Date = startDate;
newItem.Start_Hours = '03';
newItem.Start_Minutes = '00';
newItem.End_Date = startDate;
newItem.End_Hours = '23';
newItem.End_Minutes = '30';
// Create the new item
ceateDatasource.createItem();
}
If you want to save several records at the same time using client script, then what you are looking for is the Manual Save Mode. So all you have to do is go to your model's datasource and click on the checkbox "Manual Save Mode".
Then use the same code as above. The only difference is that in order to persist the changes to the server, you need to explicitly save changes. So all you have to do is add the following after the for loop block:
app.datasources.Reservation.saveChanges(function(){
//TODO: Callback handler
});
I have strings and determine the ranges of indexes. I will need later for instance .last .count for these ranges. How should I initialise the range for string to be able to get functionality .last .count for these ranges (that is obvious in swift2 but not in swift3) ?
For example, I am often using the .count for range of string in my code in swift2, like this
var str = "Hello, playground"
let myRange = str.rangeOfString("Hello")
let myCountOfRange = myRange.count
Now it is not possible to do this in swift3
var str = "Hello, playground"
let myRange = str.range(of: "Hello")
let myCountOfRange = myRange.count // type index does not conform to protocol strideable
In Swift3, to find the size of a range you can do:
var str = "Hello, playground"
let myRange = str.range(of: "Hello")
let myCountOfRange = str[myRange!].characters.count
I don't know if this is the best way, but it works.
Alternatively:
let myCountOfRange = str.distance(from: myRange!.lowerBound, to: myRange!.upperBound)
Both require access to the original collection (ie. string), and that apparently is a limitation of Swift 3. The new model for collections and indices is discussed here.
If you want to store the ranges in an array and call .count and .last on them, you can convert the Range<Index> to a CountableRange<Int> while you still have access to the collection:
var str = "Hello, playground"
let myRange = str.range(of: "Hello")!
let lb = str.distance(from: str.startIndex, to: myRange.lowerBound) as Int
let ub = str.distance(from: str.startIndex, to: myRange.upperBound) as Int
let newRange = lb..<ub
newRange.count // 5
newRange.last // 4
hi guys i am stuck converting below sql to LINQ query.
all i want is to have maximum number from list of (FA-00001 ,FA-00059)
SELECT MAX(CAST(SUBSTRING(ReferenceId, PATINDEX('%-%', ReferenceId) + 1, LEN(ReferenceId) - PATINDEX('%-%', ReferenceId)) AS int)) AS MaxReferenceId FROM [ClientRC].[dbo].[EHO_Action]
is this possible to convert to LINQ? thanks
An alternative approach using anonymous projection:
var y = (from record in
(from record in db.ClientRC
select new
{
Group = "x",
ReferenceNumber = Convert.ToInt32(record.ReferenceId.Split('-')[1])
})
group record by new { record.Group } into g
select new
{
MaxReferenceId = g.Max(p => p.ReferenceNumber)
});
http://msdn.microsoft.com/en-us/library/bb386972.aspx
var myvar = (from v in db.object where v!=null select v.id).Max();
MSDN has lots of examples for stuff like this.
Or, you can execute queries directly against a datacontext if you're using entity framework. Just make sure if you're doing anything with parameters you're parameterizing the query and not taking user input directly into it.
http://msdn.microsoft.com/en-us/library/ee358769.aspx
Try this..
var list = DBContext.EHO_Action
.Where(x => x.YourListColumn != null)
.Select(x => x.YourListColumn).ToList(); // Take the list (FA-00001 ,FA-00059) from db to a list
var maxNo = list.Max(x => Convert.ToInt32(x.Split('-')[1]));
Please change the context and column names according to your Linq context.
If you want to use sql you can do it this way..
var list = DBContext.ExecuteQuery<string>("select yourreqrdcolumn from [ClientRC].[dbo].[EHO_Action]");