I have dataabase of 2.5 million records. One column in database is empty. Now i want to fill that column by inserting in Bulk, because a simple update query takes a lot of time. But the problem is that bulkinsert starts inserting record at the end, not from the start. Here is my code:
using (SqlBulkCopy s = new SqlBulkCopy(dbConnection))
{
for (int j = 0; j < rows.Length; j++)
{
DataRow dailyProductSalesRow = prodSalesData.NewRow();
string[] temp = ((string)rows[j]["Area"]).Split(new string[] { " ", "A","a" }, StringSplitOptions.None);
if (Int32.TryParse(temp[0], out number))
{
int num1 = Int32.Parse(temp[0]);
dailyProductSalesRow["Area1"] = 1;
}
else
{
dailyProductSalesRow["Area1"] = 0;
Console.WriteLine("Invalid "+temp[0]);
}
prodSalesData.Rows.Add(dailyProductSalesRow);
}
s.DestinationTableName = prodSalesData.TableName;
foreach (var column in prodSalesData.Columns)
{
s.ColumnMappings.Add(column.ToString(), column.ToString());
}
try
{
s.WriteToServer(prodSalesData);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
If you need to update, use an UPDATE stamenet
BULK INSERT is designed to help make inserting many records faster as INSERT can be very slow and difficult to use when trying to get a large amount of data into a database.
UPDATE is already the fastest way of updating records in a database. In your case I'd guess you want a statement a bit like this based on what your BULK INSERT is apparently trying to do.
UPDATE SalesData
SET Area1 = CONVERT(INT, SUBSTRING(Area, 0, CHARINDEX('A', Area)))
If you want to try and make it faster then try looking at Optimizing Bulk Import Performance. Some of the advice there (e.g. the recovery model used by the database) may also be applicable to UPDATE performance when updating many records.
Related
I'm writing an upgrade program for moving Access 2.0 .mdb files to Access 2003 .mdb. We are staying with the mdb file structure for a couple of reasons as this is code that is in several customers locations, and the mdb allows us to utilize existing code.
The main problem:
I go through JET to read in the tables from the file.mdb and read each table into a C# datatable. I then do several checks and duplicate the table in the 2003 mdb db. I use the DataTable.PrimaryKey function to gather the columns that are primary key columns, but I don't get reliable results.
Access 2.0 shows the PrimaryKey in several tables (single column) where DataTable does not, but not always.
I have verified that I do get the PrimaryKey(s) on some tables, just not all.
DataColumn[] dcPrimaryKeyCols = OrgTbl.PrimaryKey;
//Read the Ordinal so we can order the columns correctly
for (int m = 0; m < NumCols; m++)
{
ColumnOrder[m] = OrgTbl.Columns[m].Ordinal;
if (ColumnOrder[m] != m)
MessageBox.Show("In table " + nm+ "out of order ordinal on column: " + OrgTbl.Columns[m].ColumnName);
}
lblStatus.Text = "Creating Table";
pbTableProgress.Value = 0;
pbTableProgress.Maximum = NumCols;
for (int col = 0; col < NumCols;col++ )
{
pbTableProgress.Value = col;
Application.DoEvents();
sColNm=OrgTbl.Columns[col].ColumnName.Trim();
bPrimaryKey = false;
//determine if this column is part of a primary key group
for (int k = 0; k < dcPrimaryKeyCols.Length;k++ )
{
if (dcPrimaryKeyCols[k].ColumnName.Trim().Equals(sColNm))
{
bPrimaryKey = true;
break;
}
}
I have set a breakpoint in the bPrimaryKey = true line, and it gets there sometimes, but not on all the tables where a primarykey is defined.
One thing I noted, in Access Ver 2.0, the column information for the some of the primary keys show: required = no, unique = no. I don't know if this causes JET or the C# datatable to unmark a primarykey column or if other things are at work here. But the end results is that I am not able to correctly detect ALL primarykey columns.
I am using SQL Bulk copy to read data form Excel to SQL DB. In the Database, I have two tables into which I need to insert this data from Excel. Table A and Table B which uses the ID(primary Key IDENTITY) from Table A to insert corresponding row records into Table B.
I am able to insert into one table (Table A) using the following Code.
using (SqlConnection connection = new SqlConnection(strConnection)) {
connection.Open();
using (SqlBulkCopy bulkCopy = new SqlBulkCopy(connection)) {
bulkCopy.DestinationTableName = "dbo.[EMPLOYEEINFO]";
try {
// Write from the source to the destination.
SqlBulkCopyColumnMapping NameMap = new SqlBulkCopyColumnMapping(data.Columns[0].ColumnName, "EmployeeName");
SqlBulkCopyColumnMapping GMap = new SqlBulkCopyColumnMapping(data.Columns[1].ColumnName, "Gender");
SqlBulkCopyColumnMapping CMap = new SqlBulkCopyColumnMapping(data.Columns[2].ColumnName, "City");
SqlBulkCopyColumnMapping AMap = new SqlBulkCopyColumnMapping(data.Columns[3].ColumnName, "HomeAddress");
bulkCopy.ColumnMappings.Add(NameMap);
bulkCopy.ColumnMappings.Add(GMap);
bulkCopy.ColumnMappings.Add(CMap);
bulkCopy.ColumnMappings.Add(AMap);
bulkCopy.WriteToServer(data);
}
catch (Exception ex) {
Console.WriteLine(ex.Message);
}
}
}
But then I am not sure how to extend it for two tables which are bound by Foreign Key relationship.Especially, Table B uses the Identity value from Table A Any example would be great. I googled it and none of the threads on SO couldn't give a Working example.
AFAIK bulk copy can only be used to upload into a single table. In order to achieve a bulk upload into two tables, you will therefore need two bulk uploads. Your problem comes from using a foreign key which is an identity. You can work around this, however. I am pretty sure that bulk copy uploads sequentially, which means that if you upload 1,000 records and the last record gets an ID of 10,197, then the ID of the first record is 9,198! So my recommendation would be to upload your first table, check the max id after the upload, deduct the number of records and work from there!
Of course in a high use database, someone might insert after you, so you would need to get the top id by selecting the record which matches your last one by other details (assuming a combination of (upto) all fields would be guaranteed to be unique). Only you know if this is likely to be a problem.
The alternative is not to use an identity column in the first place, but I presume you have no control over the design? In my younger days, I made the mistake of using identities, I never do now. They always find a way of coming back to bite!
For example to add the second data:
DataTable secondTable = new DataTable("SecondTable");
secondTable.Columns.Add("ForeignKey", typeof(int));
secondTable.Columns.Add("DataField", typeof(yourDataType));
...
Add data to secondTable.
(Depends on format of second data)
int cnt = 0;
foreach (var d in mySecondData)
{
DataRow newRow = secondTable.NewRow();
newRow["ForeignKey"] = cnt;
newRow["DataField"] = d.YourData;
secondTable.Rows.Add(newRow);
}
Then after you found out the starting identity (int startID).
for (int i = 0; i < secondTable.Rows.Count; i++)
{
secondTable["ForeignKey"] = secondTable["ForeignKey"] + startID;
}
Finally:
bulkCopy.DestinationTableName = "YourSecondTable";
bulkCopy.WriteToServer(secondTable);
I want to insert around 1 million records into a database using Linq in ASP.NET MVC. But when I try the following code it didn't work. It's throwing an OutOfMemoryException. And also it took 3 days in the loop. Can anyone please help me on this???
db.Database.ExecuteSqlCommand("DELETE From [HotelServices]");
DataTable tblRepeatService = new DataTable();
tblRepeatService.Columns.Add("HotelCode",typeof(System.String));
tblRepeatService.Columns.Add("Service",typeof(System.String));
tblRepeatService.Columns.Add("Category",typeof(System.String));
foreach (DataRow row in xmltable.Rows)
{
string[] servicesarr = Regex.Split(row["PAmenities"].ToString(), ";");
for (int a = 0; a < servicesarr.Length; a++)
{
tblRepeatService.Rows.Add(row["HotelCode"].ToString(), servicesarr[a], "PA");
}
String[] servicesarrA = Regex.Split(row["RAmenities"].ToString(), ";");
for (int b = 0; b < servicesarrA.Length; b++)
{
tblRepeatService.Rows.Add(row["hotelcode"].ToString(), servicesarrA[b], "RA");
}
}
HotelAmenties _hotelamenties;
foreach (DataRow hadr in tblRepeatService.Rows)
{
_hotelamenties = new HotelAmenties();
_hotelamenties.Id = Guid.NewGuid();
_hotelamenties.ServiceName = hadr["Service"].ToString();
_hotelamenties.HotelCode = hadr["HotelCode"].ToString();
db.HotelAmenties.Add(_hotelamenties);
}
db.SaveChanges();
tblRepeatService table has around 1 million rows.
Bulk inserts like this are highly inefficient in LINQtoSQL. Every insert creates at least three objects (the DataRow, the HotelAmenities object and the tracking record for it), chewing up memory on objects you don't need.
Given that you already have a DataTable, you can use System.Data.SqlClient.SqlBulkCopy to push the content of the table to a temporary table on the SQL server, then use a single insert statement to load the data into its final destination. This is the fastest way I have found so far to move many thousands of records from memory to SQL.
If performance doesn't matter and this is a 1 shot job you can stick to the way you're using. Your problem is you're only saving at the end, so entity Framework has to store and generate the SQL for 1 million operations at once, modify your code so that you save every 1000 or so inserts instead of only at the end and it should work just fine.
int i = 0;
foreach (DataRow hadr in tblRepeatService.Rows)
{
_hotelamenties = new HotelAmenties();
_hotelamenties.Id = Guid.NewGuid();
_hotelamenties.ServiceName = hadr["Service"].ToString();
_hotelamenties.HotelCode = hadr["HotelCode"].ToString();
db.HotelAmenties.Add(_hotelamenties);
if((i%1000)==0){
db.SaveChanges();
}
i++;
}
db.SaveChanges();
I'm currently building an application that needs a feature to import a user-supplied CSV file as data into a database. Each "cell" in the CSV will be stored in its own row.
Initially I was using parameterized queries to insert each row one-by-one, but the speed of the operation (520,000 inserts in one example file!) meant I'm having to reconsider that. I'm now parsing the CSV file into an IEnumerable<Answer> and handing it over to the following code to be inserted into the database in batches:
public void AddAnswers(IEnumerable<Answer> answers)
{
const int batchSize = 1000;
var values = new StringBuilder();
var i = 0;
foreach (var answer in answers)
{
if (i++ > 0)
{
values.Append(",");
}
values.AppendFormat("({0},{1},'{2}')", answer.AnswerSetId, answer.QuestionId, answer.Value.Replace("'", "''"));
if (i == batchSize)
{
// We've reached the batch size limit - send what we have so far
SendAnswerBatch(values.ToString());
values.Clear();
i = 0;
}
}
if (i > 0)
{
// Ensure any leftovers that didn't reach the maximum batch size are sent over
SendAnswerBatch(values.ToString());
}
}
private void SendAnswerBatch(string values)
{
var query = String.Format("INSERT INTO Answers (AnswerSetId,QuestionId,Value) VALUES {0}", values);
Context.Database.ExecuteSqlCommand(query);
}
This changed a large set of data from taking over 5 minutes to less than 5 seconds to insert, however I realise that basic replacing of ' with '' is not safe.
Obviously the safest way to insert a single row would be to use a parameterized query but is there a way to make such a thing work with a batch insert like this?
If at all possible, I also need it to be non-database specific - I had already considered SqlBulkCopy but the application needs to support multiple database engines.
i would suggest you use sqlBulkCopy, when inserting a lot of values, this provided to be really usefull to me
place your items into a datatable and let SqlBulkCopy do the rest.
http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlbulkcopy.aspx
I'm working on an import from a CSV file to my ASP.NET MVC3/C#/Entity Framework Application.
Currently this is my code, but I'm looking to optimise:
var excel = new ExcelQueryFactory(file);
var data = from c in excel.Worksheet(0)
select c;
var dataList = data.ToList();
List<FullImportExcel> importList = new List<FullImportExcel>();
foreach (var s in dataList.ToArray())
{
if ((s[0].ToString().Trim().Length < 6) && (s[1].ToString().Trim().Length < 7))
{
FullImportExcel item = new FullImportExcel();
item.Carrier = s[0].ToString().Trim();
item.FlightNo = s[1].ToString().Trim();
item.CodeFlag = s[2].ToString().Trim();
//etc etc (50 more columns here)
importList.Add(item);
}
}
PlannerEntities context = null;
context = new PlannerEntities();
context.Configuration.AutoDetectChangesEnabled = false;
int count = 0;
foreach (var item in importList)
{
++count;
context = AddToFullImportContext(context, item, count, 100, true);
}
private PlannerEntities AddToFullImportContext(PlannerEntities context, FullImportExcel entity, int count, int commitCount, bool recreateContext)
{
context.Set<FullImportExcel>().Add(entity);
if (count % commitCount == 0)
{
context.SaveChanges();
if (recreateContext)
{
context.Dispose();
context = new PlannerEntities();
context.Configuration.AutoDetectChangesEnabled = false;
}
}
return context;
}
This works fine, but isn't as quick as it could be, and the import that I'm going to need to do will be a minimum of 2 million lines every month. Are there any better methods out there for bulk imports?
Am I better avoiding EF altogether and using SQLConnection and inserting that way?
Thanks
I do like how you're only committing records every X number of records (100 in your case.)
I've recently written a system that once a month, needed to update the status of upwards of 50,000 records in one go - this is updating each record and inserting an audit record for each updated record.
Originally I wrote this with the entity framework, and it took 5-6 minutes to do this part of the task. SQL Profiler showed me it was doing 100,000 SQL queries - one UPDATE and one INSERT per record (as expected I guess.)
I changed this to a stored procedure which takes a comma-separated list of record IDs, the status and user ID as parameters, which does a mass-update followed by a mass-insert. This now takes 5 seconds.
In your case, for this number of records, I'd recommend creating a BULK IMPORT file and passing that over to SQL to import.
http://msdn.microsoft.com/en-us/library/ms188365.aspx
For large number of inserts in SQL Server Bulk Copy is the fastest way. You can use the SqlBulkCopy class for accessing Bulk Copy from code. You have to create an IDataReader for your List or you can use this IDataReader for inserting generic Lists I have written.
Thanks to Andy for the heads up - this was the code used in SQL, with a little help from the ever helpful, Pinal Dave - http://blog.sqlauthority.com/2008/02/06/sql-server-import-csv-file-into-sql-server-using-bulk-insert-load-comma-delimited-file-into-sql-server/ :)
DECLARE #bulkinsert NVARCHAR(2000)
DECLARE #filepath NVARCHAR(100)
set #filepath = 'C:\Users\Admin\Desktop\FullImport.csv'
SET #bulkinsert =
N'BULK INSERT FullImportExcel2s FROM ''' +
#filepath +
N''' WITH (FIRSTROW = 2, FIELDTERMINATOR = '','', ROWTERMINATOR = ''\n'')'
EXEC sp_executesql #bulkinsert
Still got a bit of work to do to work it into the code, but we're down to 25 seconds for 50000 rows instead of an hour, so a huge improvement!