I do not know if the heading is correct - so editing is allowed to make it proper.
Problem - using Vb.net code, when I read an excel file of 100,000 records, using connection string and sql query, it takes 3 minutes ( too long to me - I want a solution, please) to complete.
But, when I submit another excel file of 300,000 records ( my requirement is to read 50 Million records) - the time taken was more than 30 minutes ( I could not tolerate and killed the program)
Please help me understand this disparity and why it takes so long to read.
(I did not give any code samples because thousands of such sample codes are available on the net on how to establish a connection to a excel file ( Office 2010) and how to run a query to read a record )
Thanks in advance for your help and time. As a solution, I thought of chopping the 300,000 record file into files of 10,000 records each - but, how do I do that without wasting opening and reading time ?
Sabya
P.S - using core 2 duo with 8 GB RAM with Windows Server 2008 and Windows 7
So, i don't work with vb.net but if you familiar with java i can advice you Apache POI library. POI load all data in memory and for my cases it works perfect, after that you can store it to mysql or anything else i read a hundred of files with poi and it helps me great.
Here i find a question which looks like similar to yours.
And here you can find POI performance discussion.
And another solution can be to export excel file to csv and read it after that, i think it'll also fast.
You could temporarily disable the Macro run as soon as Excel loads.
Memory limitation is another reason, as excel could use very large amount of memory. I would exhaust out the memory banks to 16GB if I am running this large spreadsheet (100K) cells).
Make sure the excel file and the hard drive is defragmented (you can see a real impact).
If never shutdown the PC, try shutdown and restart. This can liberate processes to unload unused dlls.
Increase the pagefile.sys size to at least 2.5 times RAM so that data transaction occurs smoothly.
Ishikawa asked, if vb.net is essential - my answer is yes, because, it is a part of an application written in VB.Net Framework 4.0. He also talked about exporting the excel to csv and try - but, I am afraid, if opening and reading is taking so many hours, ( it took 9 hours !!) - converting will not help. User will be killing the process - I am sure.
Soandos asked for the query - it is - "Select top 1* from excel-file" - I am reading one by one. I think, the problem is not this query because this same query reads 100,000 records quite well.
KronoS supported Soandos and I have answered above. To his/her 2nd point, the answer is - I have to have excel as - this is whatthe user provides. I can not change it.
I do not see who answered this - but the idea of disabling Macros - is a very good point. Should I not disable all macro, all filters and unhide all - to read all data in simple way ? I will try that.
The total size of the 300,000 record excel file is 61 MB - it is not very large !! to create a memory problem ?
I found that the speed of simply reading records in excel is not linear. It reads 10,000 records in 4 sec but, reads 50,000 in 27 sec and 100,000 in 60 sec etc..I wish - if anyone can tell me how to index an excel file to read large files. I do not know what will be the problem size, when I get an excel file of 50 Million rows ?
I had similar problems with updating large excel file. my solution - update part of it, close, kill excel process, reopen, update again
oexcel.DisplayAlerts = False
obook.SaveAs(fnExcNew, 1)
obook.Close()
obook = Nothing
KillExcel()
oexcel = CreateObject("Excel.Application")
oexcel.Workbooks.Open(fnExcNew)
obook = oexcel.ActiveWorkbook
osheet = oexcel.Worksheets(1)
Private Sub KillExcel()
' Kill all excel processes
Dim pList() As Process
Dim pExcelProcess As System.Diagnostics.Process
pList = pExcelProcess.GetProcesses
For Each pExcelProcess In pList
If pExcelProcess.ProcessName.ToUpper = "EXCEL" Then
pExcelProcess.Kill()
End If
Next
End Sub
Related
I am currently working on NASDAQ data parsing and insertion into the influx database. I have taken care of all the data insertion rules (escaping special characters and organizing the according to the format : <measurement>[,<tag-key>=<tag-value>...] <field-key>=<field-value>[,<field2-key>=<field2-value>...] [unix-nano-timestamp]).
Below is a sample of my data:
apatel17#*****:~/output$ head S051018-v50-U.csv
# DDL
CREATE DATABASE NASDAQData
# DML
# CONTEXT-DATABASE:NASDAQData
U,StockLoc=6445,OrigOrderRef=22159,NewOrderRef=46667 TrackingNum=0,Shares=200,Price=73.7000 1525942800343419608
U,StockLoc=6445,OrigOrderRef=20491,NewOrderRef=46671 TrackingNum=0,Shares=200,Price=73.7800 1525942800344047668
U,StockLoc=952,OrigOrderRef=65253,NewOrderRef=75009 TrackingNum=0,Shares=400,Price=45.8200 1525942800792553625
U,StockLoc=7092,OrigOrderRef=51344,NewOrderRef=80292 TrackingNum=0,Shares=100,Price=38.2500 1525942803130310652
U,StockLoc=7092,OrigOrderRef=80292,NewOrderRef=80300 TrackingNum=0,Shares=100,Price=38.1600 1525942803130395217
U,StockLoc=7092,OrigOrderRef=82000,NewOrderRef=82004 TrackingNum=0,Shares=300,Price=37.1900 1525942803232492698
I have also created the database: NASDAQData inside influx.
The problem I am facing is this:
The file has approximately 13 million rows (12,861,906 to be exact). I am trying to insert this data using the CLI import command as below:
influx -import -path=S051118-v50-U.csv -precision=ns -database=NASDAQData
I usually get upto 5,000,000 lines before I start getting the error for insertion. I have run this code multiple times and sometimes I get the error at 3,000,000 lines as well. To figure out this error, I am running the same code on a part of the file. I divide the data into 500,000 lines each and the code successfully ran for all the smaller files. (all 26 files of 500,000 rows)
Has this happened to somebody else or does somebody know a fix for this problem wherein a huge file shows errors during data insert but if broken down and worked with smaller data size, the import works perfectly.
Any help is appreciated. Thanks
As recommended by influx documentation, it may be necessary to split your data file into several smaller ones as the http request used for issuing your writes can timeout after 5 seconds.
If your data file has more than 5,000 points, it may be necessary to
split that file into several files in order to write your data in
batches to InfluxDB. We recommend writing points in batches of 5,000
to 10,000 points. Smaller batches, and more HTTP requests, will result
in sub-optimal performance. By default, the HTTP request times out
after five seconds. InfluxDB will still attempt to write the points
after that time out but there will be no confirmation that they were
successfully written.
Alternatively you can set a limit on how much points to write per second using the pps option. This should relief some stress off your influxdb.
See:
https://docs.influxdata.com/influxdb/v1.7/tools/shell/#import-data-from-a-file-with-import
Before admins start to eating me alive, I would like to say to my defense that I cannot comment in the original publications, because I do not have the power, therefore, I have to ask about this again.
I have issues running a job in talend (Open Studio for BIG DATA!). I have an archive of 3 gb. I do not consider that this is too much since I have a computer that has 32 GB in RAM.
While trying to run my job, first I got an error related to heap memory issue, then it changed for a garbage collector error, and now It doesn't even give me an error. (just do nothing and then stops)
I found this SOLUTIONS and:
a) Talend performance
#Kailash commented that parallel is only on the condition that I have to be subscribed to one of the Talend Platform solutions. My comment/question: So there is no other similar option to parallelize a job with a 3Gb archive size?
b) Talend 10 GB input and lookup out of memory error
#54l3d mentioned that its an option to split the lookup file into manageable chunks (may be 500M), then perform the join in many stages for each chunk. My comment/cry for help/question: how can I do that, I do not know how to split the look up, can someone explain this to me a little bit more graphical
c) How to push a big file data in talend?
just to mention that I also went through the "c" but I don't have any comment about it.
The job I am performing (thanks to #iMezouar) looks like this:
1) I have an inputFile MySQLInput coming from a DB in MySQL (3GB)
2) I used the tFirstRows to make it easier for the process (not working)
3) I used the tSplitRow to transform the data form many simmilar columns to only one column.
4) MySQLOutput
enter image description here
Thanks again for reading me and double thanks for answering.
From what I understand, your query returns a lot of data (3GB), and that is causing an error in your job. I suggest the following :
1. Filter data on the database side : replace tSampleRow by a WHERE clause in your tMysqlInput component in order to retrieve fewer rows in Talend.
2. MySQL jdbc driver by default retrieves all data into memory, so you need to use the stream option in tMysqlInput's advanced settings in order to stream rows.
In the past I had to work with big files, somewhere about in the 0.1-3GB range. Not all the 'columns' were needed so it was ok to fit the remaining data in RAM.
Now I have to work with files in 1-20GB range, and they will probably grow as the time will pass. That is totally different because you cannot fit the data in RAM anymore.
My file contains several millions of 'entries' (I have found one with 30 mil entries). On entry consists in about 10 'columns': one string (50-1000 unicode chars) and several numbers. I have to sort the data by 'column' and show it. For the user only the top entries (1-30%) are relevant, the rest is low quality data.
So, I need some suggestions about in which direction to head out. I definitively don't want to put data in a DB because they are hard to install and configure for non computer savvy persons. I like to deliver a monolithic program.
Showing the data is not difficult at all. But sorting... without loading the data in RAM, on regular PCs (2-6GB RAM)... will kill some good hours.
I was looking a bit into MMF (memory mapped files) but this article from Danny Thorpe shows that it may not be suitable: http://dannythorpe.com/2004/03/19/the-hidden-costs-of-memory-mapped-files/
So, I was thinking about loading only the data from the column that has to be sorted in ram AND a pointer to the address (into the disk file) of the 'entry'. I sort the 'column' then I use the pointer to find the entry corresponding to each column cell and restore the entry. The 'restoration' will be written directly to disk so no additional RAM will be required.
PS: I am looking for a solution that will work both on Lazarus and Delphi because Lazarus (actually FPC) has 64 bit support for Mac. 64 bit means more RAM available = faster sorting.
I think a way to go is Mergesort, it's a great algorithm for sorting a
large amount of fixed records with limited memory.
General idea:
read N lines from the input file (a value that allows you to keep the lines in memory)
sort these lines and write the sorted lines to file 1
repeat with the next N lines to obtain file 2
...
you reach the end of the input file and you now have M files (each of which is sorted)
merge these files into a single file (you'll have to do this in steps as well)
You could also consider a solution based on an embedded database, e.g. Firebird embedded: it works well with Delphi/Windows and you only have to add some DLL in your program folder (I'm not sure about Lazarus/OSX).
If you only need a fraction of the whole data, scan the file sequentially and keep only the entries needed for display. F.I. lets say you need only 300 entries from 1 million. Scan the first first 300 entries in the file and sort them in memory. Then for each remaining entry check if it is lower than the lowest in memory and skip it. If it is higher as the lowest entry in memory, insert it into the correct place inside the 300 and throw away the lowest. This will make the second lowest the lowest. Repeat until end of file.
Really, there are no sorting algorithms that can make moving 30gb of randomly sorted data fast.
If you need to sort in multiple ways, the trick is not to move the data itself at all, but instead to create an index for each column that you need to sort.
I do it like that with files that are also tens of gigabytes long, and users can sort, scroll and search the data without noticing that it's a huge dataset they're working with.
Please finde here a class which sorts a file using a slightly optimized merge sort. I wrote that a couple of years ago for fun. It uses a skip list for sorting files in-memory.
Edit: The forum is german and you have to register (for free). It's safe but requires a bit of german knowledge.
If you cannot fit the data into main memory then you are into the realms of external sorting. Typically this involves external merge sort. Sort smaller chunks of the data in memory, one by one, and write back to disk. And then merge these chunks.
I had an pre-interview task, which I have completed and the solution works, however I was marked down and did not get an interview due to having used a TADODataset. I basically imported a CSV file which populated the dataset, the data had to be processed in a specific way, so I used Filtering and Sorting of the dataset to make sure that the data was ordered in the way I wanted it and then I did the logic processing in a while loop. The feedback that was received said that this was bad as it would be very slow for large files.
My main question here is if using an in memory dataset is slow for processing large files, what would have been better way to access the information from the csv file. Should I have used String Lists or something like that?
It really depends on how "big" and the available resources(in this case RAM) for the task.
"The feedback that was received said that this was bad as it would be very slow for large files."
CSV files are usually used for moving data around(in most cases that I've encountered files are ~1MB+ up to ~10MB, but that's not to say that others would not dump more data in CSV format) without worrying too much(if at all) about import/export since it is extremely simplistic.
Suppose you have a 80MB CSV file, now that's a file you want to process in chunks, otherwise(depending on your processing) you can eat hundreds of MB of RAM, in this case what I would do is:
while dataToProcess do begin
// step1
read <X> lines from file, where <X> is the max number of lines
you read in one go, if there are less lines(i.e. you're down to 50 lines and X is 100)
to process, then you read those
// step2
process information
// step3
generate output, database inserts, etc.
end;
In the above case, you're not loading 80MB of data into RAM, but only a few hundred KB, and the rest you use for processing, i.e. linked lists, dynamic insert queries(batch insert), etc.
"...however I was marked down and did not get an interview due to having used a TADODataset."
I'm not surprised, they were probably looking to see if you're capable of creating algorithm(s) and provide simple solutions on the spot, but without using "ready-made" solutions.
They were probably thinking of seeing you use dynamic arrays and creating one(or more) sorting algorithm(s).
"Should I have used String Lists or something like that?"
The response might have been the same, again, I think they wanted to see how you "work".
The interviewer was quite right.
The correct, scalable and fastest solution on any medium file upwards is to use an 'external sort'.
An 'External Sort' is a 2 stage process, the first stage being to split each file into manageable and sorted smaller files. The second stage is to merge these files back into a single sorted file which can then be processed line by line.
It is extremely efficient on any CSV file with over say 200,000 lines. The amount of memory the process runs in can be controlled and thus dangers of running out of memory can be eliminated.
I have implemented many such sort processes and in Delphi would recommend a combination of TStringList, TList and TQueue classes.
Good Luck
I am trying to index about 3 million text documents in solr. About 1/3 of these files are emails that have about 1-5 paragraphs of text in them. The remaining 2/3 files only have a few words to sentences each.
It takes Lucid/Solr nearly 1 hour to fully index the entire dataset I'm working with. I'm trying to find ways to optimize this. I have setup Lucid/Solr to only commit every 100,000 files, and it indexes the files in batches of 50,000 files at once. Memory isn't an issue anymore, as it consistently stays around 1GB of memory because of the batching.
The entire dataset has to be indexed initially. It's like a legacy system that has to be loaded to a new system, so the data has to be indexed and it needs to be as fast as possible, but I'm not sure what areas to look into to optimize this time.
I'm thinking that maybe there's a lot of little words like "the, a, because, should, if, ..." that are causing a lot of overhead and are just "noise" words. I am curious if I cut them out if it would drastically speed up the indexing time. I have been looking at the Lucid docs for a while, but I can't seem to find a way to specify what words not to index. I came across the term "stop list" but didn't see much more than a reference to it in passing.
Are there other ways to make this indexing go faster or am I just stuck with a 1 hour indexing time?
We met similar problem recently. We can't use solrj as the request and response have to go through some applications, so we take the following steps:
Creating Custom Solr Type to Stream Large Text Field!
Use GZipOutput/InputStream and Bse64Output/InputStream to compress the large text. This can reduce size of text about 85%, this can reduce the time to transfer the request/response.
To reduce memory usage at client side:
2.1 We use stream api(GSon stream or XML Stax) to read doc one by one.
2.2 Define a custom Solr Field Type: FileTextField which accepts FileHolder as value. FileTextField will eventually pass a reader to Lucene. Lucene will use the reader to read content and add to index.
2.3 When the text field is too big, first uncompress it to a temp file, create a FileHolder instance, then set the FileHolder instance as field value.
It seems from your query that Indexing time is really important for your application. Solr is a great search engine however if you need super fast indexing time and if that is a very important criteria for you, than you should go with Sphinx Search Engine. It wont take much of time for you to quickly setup and benchmark your results using Sphinx.
There can be ways (like the one you have mentioned, stopwords etc.) to optimize however whatever you do with respect to indexing time Solr won't be able to beat Sphinx. I have done benchmarking myself.
I too love Solr a lot because of its ease of use, its out of box great features like N-Gram Indexing, Faceting, Multi-core, Spelling Correctors and its integration with other apache products etc.. but when it comes to Optimized Algorithms (be it Index size, Index time etc.) Sphinx rocks!!
Sphinx too is open source. Try that out.