August 2009 - users-list

[MonetDB-users] Phrase searching with 'or'
by Roy Walter 13 Aug '09

13 Aug '09

Consider the following XQuery using two phrases: tijah:queryall("//p[about(., 'wind turbine') or about(., 'wind farm')]") It returns a restricted result set where only 'wind turbine' AND 'wind farm' are present. Substituting 'and' for 'or' in the query returns the same number of rows. Is this a bug? -- Roy

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[MonetDB-users] optimizer.exportChunk exception
by Alex Bo. 11 Aug '09

11 Aug '09

Hi, I got this error on running "Select * from tables": !TypeException:user.s6_2[154]:'optimizer.exportChunk' undefined in: _237:any := optimizer.exportChunk() !TypeException:user.s6_2[155]:'optimizer.affectedRows' undefined in: _241:any := optimizer.affectedRows() Consequent queries were successful. Seems like a bug. -- View this message in context: http://www.nabble.com/optimizer.exportChunk-exception-tp24915518p24915518.h… Sent from the monetdb-users mailing list archive at Nabble.com.

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[MonetDB-users] Query speed up
by Allen Zhang 10 Aug '09

10 Aug '09

Hi, All, I have a client program generates the following query against monetdb, can I create index on fact columns to speed thing up? What¹s the best approach to resolve this kind performance issue? SELECT DISTINCT t1.column1 FROM (fact t0 LEFT JOIN dimension1 t1 ON t0.header_id = t1.header_id) WHERE t0.column3 = 'xxxxxx' And t0.column5 IN ('item1¹, OEitem2¹, OEitem3¹, OEitem4¹); Thanks in advance. Allen

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[MonetDB-users] MonetDB/XQuery Scaleability
by listanand＠gmail.com 10 Aug '09

10 Aug '09

Dear all, I am new to MonetDB/XQuery and am considering using it for storing and processing a large number of webpages (~1million) in XML format. I am hoping to know if this is indeed the right tool, and how well it will scale to handle tasks of this magnitude. Thanks in advance

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[MonetDB-users] COPY...INTO from remote
by Matthew Jones 08 Aug '09

08 Aug '09

I noticed that COPY...INTO from a file, when executed from a remote MonetDB mclient instance tries to load the file from the system that the database is actually running on rather than the system running the remote client. Is this the expected behavior? Has anyone dealt with this or found another way to batch-load from a remote client? 73, Matthew W. Jones (KI4ZIB) http://matburt.net

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[MonetDB-users] MonetDB Scaleability
by Calum Miller 06 Aug '09

06 Aug '09

Hi, I've been doing performance tests on MondetDB to see how it scales. I've been running tests on Amazon EC2 (7GB of memory, 64-Bit, CentOS 5.2) The table I am using has 60 columns with most being just simple characters of length 2, here is the query: select CollectionDEPOTID as c0, CollectionCountryID as c1, sum(ParcelCount) as m0 from parcel_stage_short as parcel_stage_short group by c0, c1; Here are the load time in batches of 8,000,000 using the following command: COPY 8000000 RECORDS INTO parcel_stage_short FROM '/mnt/ parcel_stage_short.txt' USING DELIMITERS '\t','\n'; Rows Load Time Increase % Increase 8000000 240434.17 8000000 424937.54 184503.37 76.74% 8000000 599621.98 359187.81 149.39% 8000000 769276.70 528842.53 219.95% 8000000 889600.24 889600.24 209.35% msecs msecs As can be seen the load time increases by around 200,000 msec for each additional 8Million rows added. Any tips on how to reduce the load speed? Would it be faster to load the table in one go (tried loading in bigger batches but loader fails)? Here are the performance times for each additional batch of 8,000,000 rows: Rows 1st Query 1st Increase % 1st Increase 2nd Query 2nd Increase % Increase 08000000 1176.53 16000000 4838.52 3661.99 311.25% 2239.61 1168.30 109.05% 24000000 33947.84 32771.31 2785.43% 9323.29 8251.98 770.27% 32000000 837114.13 835937.61 71051.29% 5456.96 4385.65 409.37% 40000000 668380.26 667203.73 56709.60% 8538.02 7466.71 696.97% msecs msecs msecs msecs The performance of the 1st query is unsurprisingly poor just after the data has been copied in The performance of the same query a second time yields much faster results The performance of the monetDb with 1st/2nd query degrades as load increases. Are these results typical? Is there anything I can do to increase performance on the 1st or 2nd queries? Thanks in advance Calum

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[MonetDB-users] tijah exact matching
by Roy Walter 06 Aug '09

06 Aug '09

Is there a way to force a tijah query to return only exact matches? For example, if I search for "wind farm", as in: ("tijah:queryall[about(., wind farm)]") I get matches for "wind farm", "wind" and "farm" but say I only want matches for "wind farm"? I can of course loop through the result with contains(., "wind farm") to exclude unwanted results but that has performance implications. -- Roy

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[MonetDB-users] Get attribute value as text how?
by Roy Walter 06 Aug '09

06 Aug '09

The following XQuery fragment will add the speakername attribute as an attribute of the tag: {$res/../@speakername}: {$res} becomes: Some text... What I want is: Roy Walter: Some text... How does MonetDB/XQuery handle this? I tried: {xs:string($res/../@speakername)}: {$res} but it errors. -- Roy

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[MonetDB-users] how to read/write blob data ?
by 李坤 04 Aug '09

04 Aug '09

I want to store image files into monetdb sql server. I think there are two approaches to do it: the first one is to store the file's full path in a column with varchar type, the second one is to store the image data in a column with blob type. I don't want to see a lot of small image files in the directory, so I choose the second approach. After reading the monetdb manual, I find some examples like this: sql> insert into t1 values (1, blob '012'); I think this is not enough. I also try to use odbc api to store binary data into monetdb, but failed. So please help me to write the blob data into monetdb, as well as the read operation. Maybe there are other ways I don't know, please tell me, thanks!

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[MonetDB-users] problem in extract second
by fatar fatar 03 Aug '09

03 Aug '09

query: select extract(second from '2009-07-24 16:03:35.0000'); result : 0.00 could you please tell me why the result is zero??? and how can i get more spesific result??? Akses email lebih cepat. Yahoo! menyarankan Anda meng-upgrade browser ke Internet Explorer 8 baru yang dioptimalkan untuk Yahoo! Dapatkan di sini! http://downloads.yahoo.com/id/internetexplorer

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