March 2011 - users-list

[MonetDB-users] Get MAL from SQL
by Kusber, Michael 10 Mar '11

10 Mar '11

Hi, is there a possibility to see the MAL code generated from a specific SQL statement? Kind regards, Michael

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[MonetDB-users] Are these bugs？
by tangray 09 Mar '11

09 Mar '11

hi all when i use c++ pragrm to insert some data into a table,the program crashes,the message is below: so i use gdb to debug the bug, i find that these places may be bugs： 1. out of bounds access file mapi.c function: mapi_param_store 2356 strncpy(hdl->query + k, p, q - p); 2357 k += q - p; 2358 hdl->query[k] = 0; q-p is equal or bigger than lim - k ,the strncpy will hava a out of bounds access. this may be the reason to crash. 2. out of bounds access file:mapi.c function: mapi_param_store 2411 case MAPI_DOUBLE: 2412 checkSpace(20); 2413 sprintf(hdl->query + k, "%.17g", *(double *) src); 2414 break; sprintf(hdl->query + k, "%.17g", *(double *) src) , sprintf function with "%.17g" format may produces a string longer than 20,eg： double d = 0.000200000000000001; double d = 0.000200000000000001; printf("%.17g",d); the result is : 0.00020000000000000101 so i think, in some paticular condition ,this will hava a out of bounds access too. I'm working with MonetDB Server v5.22.3, based on kernel 1.40.3 over fedora 12.

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[MonetDB-users] lose some datas of a table's one field, how can this happen?
by tangray 08 Mar '11

08 Mar '11

Hi when execute sql : select * from td_ind_security_held where id = 1560000 in DbVisualizer 7.1.1,it appears "protocol violation: unexpected line in data block" td_ind_security_held has 30 columns(1 int,6 varchar, others decimal) and 7219618 rows. so i count field's records one by one , all fields's records are equal to 7219618 except the allgain's records, it is only 658337. it obviously lost some data. when program inserted the data into the table , the monet server carshed out some times, can this be the reson for the lose? I'm working with MonetDB Server v5.22.3, based on kernel 1.40.3 (downloaded msi from sourceforge) over Windows XP SP3.

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Re: [MonetDB-users] MonetDB/XQuery JDBC result issue
by Wouter Alink 04 Mar '11

04 Mar '11

Hello Rob, Yes, the good thing about the JDBC interface is that the result is streamed to the client, so that there is no large memory-consumption on the client-side. However, be aware that, due to the way MonetDB works internally, the whole result is first computed and kept in memory at the server, before it is shipped to the client. This will for most use-cases not be a problem, but if you are calculating huge result sets it might. If you only fetch the first 10 rows of a result at the client, you may want to wrap a "subsequence(<your-query>, 1, 10)" around your query. Kind regards, Wouter On Fri, Mar 4, 2011 at 3:42 PM, Rob Fynes <monetdbmail(a)gmail.com> wrote: > Hi Wouter, > > Thanks for the response. You were right about that, it's working fine now. > I was thrown slightly when I saw the MonetDB documentation that said "The > result comes back as a single-row single-column multi-line string result". I > figured that the 'entire' set of results would be stuffed into one row and > one column in the result set object. In retrospect, this wouldn't make much > sense, since you could end up with a *really* big string! > > Thanks, > -Rob > > > On Wed, Mar 2, 2011 at 1:46 PM, Wouter Alink <wouter.alink(a)gmail.com>wrote: > >> Dear Rob Fynes, >> >> You have already provided the answer in your email. XQuery specifies that >> a result is actually a sequence of items. The "XQueryResult"-node has only >> been added to convert the actual result sequence into a valid XML fragment. >> Using XQuery over JDBC works like SQL; you can iterate over the results. >> There is no artificial XQueryResult-node added. >> >> For example: >> >> ResultSet rs = conn.executeQuery("...."); >> while(rs.next()) { >> .. do something with the result .. >> } >> >> With kind regards, >> Wouter Alink >> >> >> >> On Tue, Mar 1, 2011 at 10:13 PM, Rob Fynes <monetdbmail(a)gmail.com>wrote: >> >>> Hello, >>> >>> I've been having an issue with MonetDB/XQuery using the JDBC driver. >>> Essentially, when I supply an *XPath* query such as the following: >>> >>> pf:collection("collection_name")//stations[date/year>=2010] >>> >>> ... using the mclient utility, there's no problem. The result is an >>> <XQueryResult> root node containing all the relevant 'stations' nodes as >>> requested by the query. >>> However, if I issue the same query to the server from a Java application >>> using the JDBC driver for MonetDB, the string result that is returned merely >>> contains one 'stations' node (the first one that gets processed, I think). >>> >>> My guess is that the resultset (of 'stations' nodes) is not being wrapped >>> in a root node, as is the case when querying using the mclient utility. >>> But I'm unsure if this due to a bug, or if there's something that I'm not >>> doing correctly. >>> >>> I'm also aware that this issue can be resolved by modifying the query >>> (when using JDBC) to something such as: >>> >>> <result> { >>> pf:collection("collection_name")//stations[date/year>=2010] >>> } </result> >>> >>> ... but I have reasons for not wanting to do this. >>> Any help is much appreciated. If anyone needs more information, just let >>> me know (and if it makes any difference, I'm running a local server >>> instance). >>> >>> Cheers, >>> -Rob >>> >>> >>> ------------------------------------------------------------------------------ >>> Free Software Download: Index, Search & Analyze Logs and other IT data in >>> Real-Time with Splunk. Collect, index and harness all the fast moving IT >>> data >>> generated by your applications, servers and devices whether physical, >>> virtual >>> or in the cloud. Deliver compliance at lower cost and gain new business >>> insights. http://p.sf.net/sfu/splunk-dev2dev >>> _______________________________________________ >>> MonetDB-users mailing list >>> MonetDB-users(a)lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/monetdb-users >>> >>> >> >

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[MonetDB-users] MonetDB/XQuery JDBC result issue
by Rob Fynes 02 Mar '11

02 Mar '11

Hello, I've been having an issue with MonetDB/XQuery using the JDBC driver. Essentially, when I supply an *XPath* query such as the following: pf:collection("collection_name")//stations[date/year>=2010] ... using the mclient utility, there's no problem. The result is an <XQueryResult> root node containing all the relevant 'stations' nodes as requested by the query. However, if I issue the same query to the server from a Java application using the JDBC driver for MonetDB, the string result that is returned merely contains one 'stations' node (the first one that gets processed, I think). My guess is that the resultset (of 'stations' nodes) is not being wrapped in a root node, as is the case when querying using the mclient utility. But I'm unsure if this due to a bug, or if there's something that I'm not doing correctly. I'm also aware that this issue can be resolved by modifying the query (when using JDBC) to something such as: <result> { pf:collection("collection_name")//stations[date/year>=2010] } </result> ... but I have reasons for not wanting to do this. Any help is much appreciated. If anyone needs more information, just let me know (and if it makes any difference, I'm running a local server instance). Cheers, -Rob

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[MonetDB-users] draft message
by Martin Kersten 01 Mar '11

01 Mar '11

Dear MonetDB users and developers, The preparations for the March 2011 release are on target. This release will feature a much simplified installation and compilation process using a unified bootstrap/configure/make/install. Ofcourse, installers and RPMs are also provided. Furthermore, the March 2011 release will be the freeze of the MonetDB XQuery source tree. It will remain downloadable from the website, but no active development or maintenance is foreseen. In April 2011 a MonetDB/SQL feature release will mark the split of the two code bases. From that point onward, we will primarily be concerned with SQL and its enhancements. Saying goodbye to the very old mserver4 code base, also triggered a major code renovation activity. The MonetDB/SQL code base will be cleaned from legacy code, 1-time experimental code, and all that is not strictly needed for the intended functionality. We expect that this cleanup will simplify maintenance in the future. The results of the renovation step will become visible in the fall of 2011. We plan for a smooth transition step for existing SQL environments. However, under the hood, we will change the MAL and kernel library interfaces significantly. To assess the consequences in the community we would like to learn about projects that directly address the MAL or GDK layer. Please send us an email at info(a)monetdb.org with the project highlights. regards, Martin Kersten

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