I'm using ExecuteStoreCommand to facilitate bulk deletes.
This Works
// ExecuteStoreCommand syntax via http://stackoverflow.com/a/13024320/740639
// Delete all of today's events
DateTime eventDate = DateTime.Now;
string sql = "DELETE FROM EventCalendar WHERE EventDate = {0}";
context.ObjectContext.ExecuteStoreCommand(sql, new object[] { eventDate });
I want to do this, but it does not work
I get an ArgumentException: "No mapping exists from object type System.DateTime[] to a known managed provider native type."
// Delete all of the events for the past 3 days
DateTime[] eventDates = new DateTime[] {
DateTime.Now.AddDay(-1),
DateTime.Now.AddDay(-2),
DateTime.Now.AddDay(-3)
};
string sql = "DELETE FROM EventCalendar WHERE EventDate IN ({0})";
context.ObjectContext.ExecuteStoreCommand(sql, new object[] { eventDates });
Proposed Solution
I could convert my DateTime[] into the string "'2013-06-24', '2013-06-23', '2013-06-22'" and pass that as the parameter, but that seems like a hack.
I know there are libraries that add bulk delete support to EF, but I don't want to go that route at this time.
Any suggestions?
If you manipulate the string, every time you change the dates you will get a slightly different SQL statement. It may look the same, but the string is different and will have a different hash. So this subverts caching of the execution plan and kills performance.
You can't really pass parameters in an IN clause the way you're thinking. There are some other ideas in this post that might work, but if you read the notes they all say they have lousy performance.
If you can be assured that you will have a fixed number of inputs, you could use the technique of passing them as separate parameters:
... WHERE EventDate IN (#dt1, #dt2, #dt3)
Otherwise, I would go with an approach like Tom suggested, pass them as a delimited string and parse it on the server.
Also - since you are doing an exact match, you probably want to snap to midnight using DateTime.Today rather than DateTime.Now, or use the .Date property of an existing DateTime.
Here's another suggestion, if you really are just trying to delete for the last three days, why not do this?
string sql = "DELETE FROM EventCalendar WHERE EventDate BETWEEN {0} AND {1}";
context.ObjectContext.ExecuteStoreCommand(sql,
new object[] { DateTime.Today.AddDays(-3), DateTime.Today.AddDays(-1) });
Or with a bit of thought, you could probably just use sql getdate() and similar functions instead of passing parameters at all.
You could combine the dates with a delimiter on the .net side, pass it through as a paramter, and then use a Table-Valued function to split a delimited string on the server side.
Pass in something like "2013-06-24|2013-06-23|2013-06-22"
http://ole.michelsen.dk/blog/split-string-to-table-using-transact-sql/
Related
I am doing bulk insert into a SQL table using Dapper plus. Here is the code
DapperPlusManager.Entity<HardwareComponentType>("WithInsertIfNotExists").Table("dbo.Components")
.UseBulkOptions(options => {
options.InsertIfNotExists = true;
}).Identity(x=>x.ComponentId).Map("Name", "Name").Map("Status", "Status").MapValue("getDate()", "ModifiedDateTime");
As you can see, for the column, "modifiedDateTime, I am trying to pass "getDate", but I am unable to do so. I am getting exception. Basically, it is taking that as a string.
How do I pass getDate() as parameter in this syntax, that is my question.
The Map method can take any value, such as:
.Map(x => DateTime.Now, "ModifiedDateTime")
That is important to use the x => part, as it means the DateTime.Now will be evaluated for every entity and every time this method is called.
The MapValue method should only be used if the ModifiedDateTime is a constant. For example, if you are creating a custom DapperContext only for this BulkInsert, so all entities will have the same value. But in your case, you look using the GlobalContextMapping, so the Map(x => method is the one you are looking for.
When you use NHibernate to "fetch" a mapped object, it outputs a SELECT query to the database. It outputs this using parameters; so if I query a list of cars based on tenant ID and name, I get:
select Name, Location from Car where tenantID=#p0 and Name=#p1
This has the nice benefit of our database creating (and caching) a query plan based on this query and the result, so when it is run again, the query is much faster as it can load the plan from the cache.
The problem with this is that we are a multi-tenant database, and almost all of our indexes are partition aligned. Our tenants have vastly different data sets; one tenant could have 5 cars, while another could have 50,000. And so because NHibernate does this, it has the net effect of our database creating and caching a plan for the FIRST tenant that runs it. This plan is likely not efficient for subsequent tenants who run the query.
What I WANT to do is force NHibernate NOT to parameterize certain parameters; namely, the tenant ID. So I'd want the query to read:
select Name, Location from Car where tenantID=55 and Name=#p0
I can't figure out how to do this in the HBM.XML mapping. How can I dictate to NHibernate how to use parameters? Or can I just turn parameters off altogether?
OK everyone, I figured it out.
The way I did it was overriding the SqlClientDriver with my own custom driver that looks like this:
public class CustomSqlClientDriver : SqlClientDriver
{
private static Regex _partitionKeyReplacer = new Regex(#".PartitionKey=(#p0)", RegexOptions.Compiled);
public override void AdjustCommand(IDbCommand command)
{
var m = _tenantIDReplacer.Match(command.CommandText);
if (!m.Success)
return;
// replace the first parameter with the actual partition key
var parameterName = m.Groups[1].Value;
// find the parameter value
var tenantID = (IDbDataParameter ) command.Parameters[parameterName];
var valueOfTenantID = tenantID.Value;
// now replace the string
command.CommandText = _tenantIDReplacer.Replace(command.CommandText, ".TenantID=" + valueOfTenantID);
}
} }
I override the AdjustCommand method and use a Regex to replace the tenantID. This works; not sure if there's a better way, but I really didn't want to have to open up NHibernate and start messing with core code.
You'll have to register this custom driver in the connection.driver_class property of the SessionFactory upon initialization.
Hope this helps somebody!
I have some images stored in the default cluster in my OrientDB database. I stored them by implementing the code given by the documentation in the case of the use of multiple ORecordByte (for large content): http://orientdb.com/docs/2.1/Binary-Data.html
So, I have two types of object in my default cluster. Binary datas and ODocument whose field 'data' lists to the different record of binary datas.
Some of the ODocument records' RID are used in some other classes. But, the other records are orphanized and I would like to be able to retrieve them.
My idea was to use
select from cluster:default where #rid not in (select myField from MyClass)
But the problem is that I retrieve the other binary datas and I just want the record with the field 'data'.
In addition, I prefer to have a prettier request because I don't think the "not in" clause is really something that should be encouraged. Is there something like a JOIN which return records that are not joined to anything?
Can you help me please?
To resolve my problem, I did like that. However, I don't know if it is the right way (the more optimized one) to do it:
I used the following SQL request:
SELECT rid FROM (FIND REFERENCES (SELECT FROM CLUSTER:default)) WHERE referredBy = []
In Java, I execute it with the use of the couple OCommandSQL/OCommandRequest and I retrieve an OrientDynaElementIterable. I just iterate on this last one to retrieve an OrientVertex, contained in another OrientVertex, from where I retrieve the RID of the orpan.
Now, here is some code if it can help someone, assuming that you have an OrientGraphNoTx or an OrientGraph for the 'graph' variable :)
String cmd = "SELECT rid FROM (FIND REFERENCES (SELECT FROM CLUSTER:default)) WHERE referredBy = []";
List<String> orphanedRid = new ArrayList<String>();
OCommandRequest request = graph.command(new OCommandSQL(cmd));
OrientDynaElementIterable objects = request.execute();
Iterator<Object> iterator = objects.iterator();
while (iterator.hasNext()) {
OrientVertex obj = (OrientVertex) iterator.next();
OrientVertex orphan = obj.getProperty("rid");
orphanedRid.add(orphan.getIdentity().toString());
}
I developing web application with play framework 2.3.8 and scala, with complex architecture on backend and front-end side. As backend we use MS SQL, with many stored procedures, and called it by anorm. And here one of the problems.
I need to update some fields in database. The front end calls play framework, and recive name of the field, and value. Then I parse, field name, and then I need to generate SQL Query for update field. I need assign null, for all parameters, except recived parameter. I try to do it like that:
def updateCensusPaperXX(name: String, value: String, user: User) = {
DB.withConnection { implicit c =>
try {
var sqlstring = "Execute [ScXX].[updateCensusPaperXX] {login}, {domain}"
val params = List(
"fieldName1",
"fieldName2",
...,
"fieldNameXX"
)
for (p <- params){
sqlstring += ", "
if (name.endsWith(p))
sqlstring += value
else
sqlstring += "null"
}
SQL(sqlstring)
.on(
"login" -> user.login,
"domain" -> user.domain,
).execute()
} catch {
case e: Throwable => Logger.error("update CensusPaper04 error", e)
}
}
}
But actually that doesn't work in all cases. For example, when I try to save string, it give's me an error like:
com.microsoft.sqlserver.jdbc.SQLServerException: Incorrect syntax near 'some phrase'
What is the best way to generate sql query using anorm with all nulls except one?
The reason this is happening is because when you write the string value directly into the SQL statement, it needs to be quoted. One way to solve this would be to determine which of the fields are strings and add conditional logic to determine whether to quote the value. This is probably not the best way to go about it. As a general rule, you should be using named parameters rather than building a string to with the parameter values. This has a few of benefits:
It will probably be easier for you to diagnose issues because you will get more sensible error messages back at runtime.
It protects against the possibility of SQL injection.
You get the usual performance benefit of reusing the prepared statement although this might not amount to much in the case of stored procedure invocation.
What this means is that you should treat your list of fields as named parameters as you do with user and domain. This can be accomplished with some minor changes to your code above. First, you can build your SQL statement as follows:
val params = List(
"fieldName1",
"fieldName2",
...,
"fieldNameXX"
)
val sqlString = "Execute [ScXX].[updateCensusPaperXX] {login}, {domain}," +
params.map("{" + _ + "}").mkString{","}
What is happening above is that you don't need to insert the values directly, so you can just build the string by adding the list of parameters to the end of your query string.
Then you can go ahead and start building your parameter list. Note, the parameters to the on method of SQL is a vararg list of NamedParameter. Basically, we need to create Seq of NamedParameters that covers "login", "domain" and the list of fields you are populating. Something like the following should work:
val userDomainParams: Seq[NamedParameter] = (("login",user.login),("domain",user.domain))
val additionalParams = params.map(p =>
if (name.endsWith(p))
NamedParameter(p, value)
else
NamedParameter(p, None)
).toSeq
val fullParams = userDomainParams ++ additionalParams
// At this point you can execute as follows
SQL(sqlString).on(fullParams:_*).execute()
What is happening here is that you building the list of parameters and then using the splat operator :_* to expand the sequence into the varargs needed as arguments for the on method. Note that the None used in the NamedParameter above is converted into a jdbc NULL by Anorm.
This takes care of the issue related to strings because you are no longer writing the string directly into the query and it has the added benefit eliminating other issues related with writing the SQL string rather than using parameters.
from f in CUSTOMERS
where depts.Contains(f.DEPT_ID)
select f.NAME
depts is a list (IEnumerable<int>) of department ids
This query works fine until you pass a large list (say around 3000 dept ids) .. then I get this error:
The incoming tabular data stream (TDS) remote procedure call (RPC) protocol stream is incorrect. Too many parameters were provided in this RPC request. The maximum is 2100.
I changed my query to:
var dept_ids = string.Join(" ", depts.ToStringArray());
from f in CUSTOMERS
where dept_ids.IndexOf(Convert.ToString(f.DEPT_id)) != -1
select f.NAME
using IndexOf() fixed the error but made the query slow. Is there any other way to solve this? thanks so much.
My solution (Guids is a list of ids you would like to filter by):
List<MyTestEntity> result = new List<MyTestEntity>();
for(int i = 0; i < Math.Ceiling((double)Guids.Count / 2000); i++)
{
var nextGuids = Guids.Skip(i * 2000).Take(2000);
result.AddRange(db.Tests.Where(x => nextGuids.Contains(x.Id)));
}
this.DataContext = result;
Why not write the query in sql and attach your entity?
It's been awhile since I worked in Linq, but here goes:
IQuery q = Session.CreateQuery(#"
select *
from customerTable f
where f.DEPT_id in (" + string.Join(",", depts.ToStringArray()) + ")");
q.AttachEntity(CUSTOMER);
Of course, you will need to protect against injection, but that shouldn't be too hard.
You will want to check out the LINQKit project since within there somewhere is a technique for batching up such statements to solve this issue. I believe the idea is to use the PredicateBuilder to break the local collection into smaller chuncks but I haven't reviewed the solution in detail because I've instead been looking for a more natural way to handle this.
Unfortunately it appears from Microsoft's response to my suggestion to fix this behavior that there are no plans set to have this addressed for .NET Framework 4.0 or even subsequent service packs.
https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=475984
UPDATE:
I've opened up some discussion regarding whether this was going to be fixed for LINQ to SQL or the ADO.NET Entity Framework on the MSDN forums. Please see these posts for more information regarding these topics and to see the temporary workaround that I've come up with using XML and a SQL UDF.
I had similar problem, and I got two ways to fix it.
Intersect method
join on IDs
To get values that are NOT in list, I used Except method OR left join.
Update
EntityFramework 6.2 runs the following query successfully:
var employeeIDs = Enumerable.Range(3, 5000);
var orders =
from order in Orders
where employeeIDs.Contains((int)order.EmployeeID)
select order;
Your post was from a while ago, but perhaps someone will benefit from this. Entity Framework does a lot of query caching, every time you send in a different parameter count, that gets added to the cache. Using a "Contains" call will cause SQL to generate a clause like "WHERE x IN (#p1, #p2.... #pn)", and bloat the EF cache.
Recently I looked for a new way to handle this, and I found that you can create an entire table of data as a parameter. Here's how to do it:
First, you'll need to create a custom table type, so run this in SQL Server (in my case I called the custom type "TableId"):
CREATE TYPE [dbo].[TableId] AS TABLE(
Id[int] PRIMARY KEY
)
Then, in C#, you can create a DataTable and load it into a structured parameter that matches the type. You can add as many data rows as you want:
DataTable dt = new DataTable();
dt.Columns.Add("id", typeof(int));
This is an arbitrary list of IDs to search on. You can make the list as large as you want:
dt.Rows.Add(24262);
dt.Rows.Add(24267);
dt.Rows.Add(24264);
Create an SqlParameter using the custom table type and your data table:
SqlParameter tableParameter = new SqlParameter("#id", SqlDbType.Structured);
tableParameter.TypeName = "dbo.TableId";
tableParameter.Value = dt;
Then you can call a bit of SQL from your context that joins your existing table to the values from your table parameter. This will give you all records that match your ID list:
var items = context.Dailies.FromSqlRaw<Dailies>("SELECT * FROM dbo.Dailies d INNER JOIN #id id ON d.Daily_ID = id.id", tableParameter).AsNoTracking().ToList();
You could always partition your list of depts into smaller sets before you pass them as parameters to the IN statement generated by Linq. See here:
Divide a large IEnumerable into smaller IEnumerable of a fix amount of item