Re: Big Slowdown (15-20X ) on import functions in Monetdb October 2014 Release

Thanks For Looking in to this! As of now we are using MonetDB 5 server v11.17.17 "Jan2014-SP2” build, ( after rolling back from October 2014 feature build). With same client code from our side both versions have huge difference in loading performance, we saw that from 30 minutes it was taking 12 hours to upload same files to newer monetdb. We were using local storage in these tests with SSD drives so I will not expect it to take 12 hours in uploading the files. We also used some of these test results for combining files and then loading them in to database to keep memory footprint under tab :) with older version of monetdb(Jan2014-SP2) as it used to crash when memory spikes, on crash/segfaults experience was good with October release. Hopefully some patch on October build will resolve this problem and we will be able to take benefit of it stability! Thanks again for looking in to this and I will be happy to provide any additional help / information which can enable your team to make product better!! Regards, Ashish -----Original Message----- From: Dimitar Nedev Date: Wednesday, 26 November 2014 7:08 pm To: Ashish Singh Cc: "users-list@monetdb.org" Subject: Re: Big Slowdown (15-20X ) on import functions in Monetdb October 2014 Release

Hi Ashish,

We tested your data on a virtualized instance with comparable specs to the one you mentioned. I can confirm on the latest MonetDB Oct2014-SP1 release, loading the individual files takes longer than the single large one. This is only natural, since mclient runs in auto-commit modeby default, meaning at each SQL statement is a separate transaction. As a result, for each COPY INTO, and thus for each file loaded, a new transaction is created. Transactions are written to disk by the transaction logger, before being persisted in primary storage. This is of course a lot of extra I/O operations, compared to loading the data in a single SQL statement.

There is a solution. You can turn the auto-commit off, marking the beginning of the transaction with "START TRANSACTION". After all files are loaded, terminate it with "COMMIT". With bundling the data loading in a single transaction, I can confirm that the loading time for the set of individual files was about 4 minutes. You can fine more info useful info on the Loading Bulk Data page: https://www.monetdb.org/Documentation/Cookbooks/SQLrecipes/LoadingBulkData

We have not tested yet if there's significant difference when loading multiple small files with older versions of MonetDB. Which version of the database did you use before? Also, is the storage for your VM mounted locally or over the network?

I hope this helps.

Best regards, Dimitar

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On 2014-Nov-21, at 18:54 , Ashish Kumar Singh wrote:

Hey guys,

Just double checking with you guys if there are any plans to see if reported behaviour is an issue, and how can i help?

Regards, Ashish

Sent from my iPad

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On 18-Nov-2014, at 10:42 pm, Ashish Kumar Singh wrote:

Sure, take your time! We have older release of monetdb.

Whenever you guys plan to have a look do let me know i can help in terms providing a test environment, machine etc.. For couple days if that helps.

Sent from my iPad

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On 18-Nov-2014, at 10:27 pm, Stefan Manegold wrote:

Hi Ashish,

please bear with us!

We highly appreciate your feedback and will have a closer look at the reported problem as soon as our time and other obligations allow so.

Please be aware that the members of this mailing-list provide free-of-charge voluntary spare-time best-effort services.

For commercial support, please also consider https://www.monetdbsolutions.com/

Thanks! Stefan

----- Original Message -----

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Hi all,

Are you guys able to reproduce this issue? Any help required from my side do let me know.

Regards, Ashish

Sent from my iPad

On 17-Nov-2014, at 5:24 pm, Ashish Kumar Singh < ashishkumar.singh@altair.com

...

wrote:

Hi,

Below are the steps.

Unzip archive in to /opt/monetdb_test/ directroy to minimise changes in the script datbase can live anywhere in the file system.

Single Big File Import:

1. First create a database using Monetdb October2014 build called pbsworks 2. Create data base schema using schema provided in file schema.sql.

Cat all files present inside testdata directory in to on single file by using following command:

cat * > ../merged_data

Load this merged file in to database using script single_import.sql from mclient

Note down the timing, usually 3-5 minutes on 4 core 17 GB machine on amazon.

Multiple small File Import: 1. First create a database using Monetdb October2014 build called pbsworks 2. Create data base schema using schema provided in file schema.sql. 3. Load files in to database using multiple_import.sql using mclient

Regards,

Ashish

From: Anthony Damico < ajdamico@gmail.com > Reply-To: " users-list@monetdb.org " < users-list@monetdb.org > Date: Monday, 17 November 2014 3:51 pm To: " users-list@monetdb.org " < users-list@monetdb.org > Cc: " developers-list@monetdb.org " < developers-list@monetdb.org > Subject: Re: Big Slowdown (15-20X ) on import functions in Monetdb October 2014 Release

please provide a list of every command that you executed to reproduce the problem. you need to make the list of commands as short as possible, so people trying to help you are not wasting time on irrelevant code.. thanks!!

On Mon, Nov 17, 2014 at 4:22 AM, Ashish Kumar Singh < ashishkumar.singh@altair.com > wrote:

Thanks for looking in to it,

I have uploaded required test files to you at below link:

https://ftin.india.altair.com:8443/message/eJCZlisrascBO00ffEVsQu

Regards, Ashish

From: Anthony Damico < ajdamico@gmail.com > Reply-To: " users-list@monetdb.org " < users-list@monetdb.org > Date: Saturday, 15 November 2014 2:40 pm To: " users-list@monetdb.org " < users-list@monetdb.org > Cc: " developers-list@monetdb.org " < developers-list@monetdb.org >

Subject: Re: Big Slowdown (15-20X ) on import functions in Monetdb October 2014 Release

could you provide a minimal reproducible example? the less code that re-creates the problem, the better. thanks

http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-repro ducible-example

On Sat, Nov 15, 2014 at 1:45 AM, Ashish Kumar Singh < ashishkumar.singh@altair.com > wrote:

Additional information here,

If I merge all these files in to one file and then import to monetdb then time taken is 3-5 minutes as compared to 10-15 hours with October 2014 branch.

Hopefully some one from moentdb team will look in to this. I am glad to see that inspite of this slowness ( due to which this build is unusable) the segfaults are gone!

Regards, Ashish

From: Ashish Singh < ashishkumar.singh@altair.com > Date: Friday, 14 November 2014 7:41 pm To: " developers-list@monetdb.org " < developers-list@monetdb.org > Cc: " users-list@monetdb.org " < users-list@monetdb.org > Subject: Re: Big Slowdown (15-20X ) on import functions in Monetdb October 2014 Release

Is any body else seeing this problem with October,2014 release?

I wish developer team can provide some insights in this area.

Regards, Ashish

From: Ashish Singh < ashishkumar.singh@altair.com > Date: Thursday, 13 November 2014 11:22 pm To: " developers-list@monetdb.org " < developers-list@monetdb.org > Cc: " users-list@monetdb.org " < users-list@monetdb.org > Subject: Big Slowdown (15-20X ) on import functions in Monetdb October 2014 Release

All,

With October,2014 release we are stucked in to very strange performance issue while importing data on virtualised environments.

On Virtual machines in our local VMware servers and amazon machine we are seeing import performance has downgraded to close to 15 to 20 while importing ~ 2000 files as compared to 1 hour time being taken with old release. This we are seeing consistently with CentOS, SLES vm and configuration is 4 Core 33 GB machine. We tried on quite a few amazon vm just to make sure its not an issue with a particular instance setup.

On a physical machine of 4 core 24 GB we are able to match speed of import with old monetdb. We are issuing copy into command through JDBC connection.

Can you guys help me with pointers on this issue, I will be happy to share any debug info.

Regards, Ashish Kumar Singh Mobile: +91-9972045095 Skype: toashishk@gmail.com

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