December 2013 - users-list

[MonetDB-users] Proofreading your professional documents
by Richard Hounslow 24 Feb '24

24 Feb '24

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Fwd: Bulk-loading in monetdb with primary key constraint
by Vasilis Efthymiou 23 Dec '13

23 Dec '13

I am trying to bulk-load a list of objects into a one-column (primary key) db. The only reason is to remove duplicates. I can't load the list in memory, because the file size is way greater than my memory size. I use monetdb's COPY-INTO<http://www.monetdb.org/Documentation/Manuals/SQLreference/CopyInto>command, but I don't want it to fail when there is a duplicate. I want it to add everything that is not a duplicate and skip the duplicates. Is there any way to do that with monetdb? Any other way? Thank you in advance!

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varchar split function
by imad hajj chahine 17 Dec '13

17 Dec '13

Hi, I am trying to implement a function that split a varchar and returns a table with the splitted values. this is what i have so far but i dont know how to complete the implementation. CREATE FUNCTION EV_SPLIT(stringtosplit varchar(255), chartospliton char) RETURNS TABLE (id int, val varchar(255), hashval BIGINT) BEGIN --if(EV_TABLEEXISTS('tmp_evsplitres') = 0) --then -- create local temporary table tmp_evsplitres (id int, val varchar(255), hashval BIGINT); --end if; declare idx int, tmpVal varchar(255); set idx = 0; --start transaction; while (position(chartospliton in str)>0) do set tmpVal = substring(str, 0, position(',' in str)-1); insert into tmp_evsplitres values(idx, tmpVal, hash(tmpVal)); set str = substring(str, position(',' in str), length(str)); set idx = idx + 1; end while; insert into tmp_evsplitres values(idx, str, hash(str)); RETURN TABLE ( select * from tmp_evsplitres ); --commit; END;

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Inline function much faster than UDF in C?
by Alastair McKinley 13 Dec '13

13 Dec '13

Hi everyone, I have only been using MonetDB for a few weeks now and I have come across a very unexpected result when using User Defined Functions in C. I have a query which does essentially this: TABLE small_table ( int col1; float p; ); TABLE big_table ( int col1; int col2; float p; ); SELECT col1,1+SUM(MY_FUNCTION(big.p,small.p)) FROM small_table small inner join big_table big on big.col2 == small.col1 group by big.col1; My function is f(x,y) = 0.7213*(x*ln(x/x+y) + y*ln(y/x+y)) I wrote an optimised version of this function using sse intrinsics in C and compiled it into MonetDB. To my surprise, I discovered that writing this function inline in the query like so: 1+SUM(0.7213475*(big.p*LOG(big.p/(big.p+small.p))+small.p*LOG(small.p/(big.p+small.p)))) is a lot faster! The query takes approx 2 seconds with the C version and less than 0.5 seconds with the inline version in SQL! Can anyone explain this strange result? Best regards, Alastair

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BUG 3259 should be re-opened
by Roberto Cornacchia 12 Dec '13

12 Dec '13

Hello, I cannot re-open bug 3259, but I believe t should be. After the bug had been fixed by Niels, it seems to have been re-introduced. The changeset below (after the fix) approves a MAL plan that in fact is the wrong one the original report refers to: the join has again been replaced by a CROSS-PRODUCT followed by inequality selections. Changeset d0b65a3e8eb6<http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=d0b65a3e8eb6>, made by Stefan Manegold <Stefan.Manegold(a)cwi.nl> in the MonetDB repo, refers to this bug. For complete details, see http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=d0b65a3e8eb6 Changeset description: between.Bug-3259: approved new MAL plan after changeset 79e66f677113 <http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=79e66f677113>

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create a database
by Gaetano Mele 12 Dec '13

12 Dec '13

Hello can you tell me how do i create a new database with monetdb? Thanks

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Dump database with user != monetdb
by Klaus Kruse 10 Dec '13

10 Dec '13

Hello, I posted my issues with dumping a database from MonetDB a while ago. The issue is still ongoing. It reduces to the fact, that no other user than the default monetdb-user has enough rights to dump a database. I played around with the various tables regarding users and schemas (sys.auths , sys.user_role ) but it's still failing on 'sys.db_user_info' : msqldump -u dump test password: -- msqldump dump database Tue Dec 10 17:19:43 2013 -- MonetDB v11.15.7 (Feb2013-SP2), 'mapi:monetdb://dev01.picalike.corpex-kunden.de:50000/test' START TRANSACTION; MAPI = (dump) /tmp/.s.monetdb.50000 QUERY = SELECT "name" FROM "sys"."auths" WHERE "name" NOT IN (SELECT "name" FROM "sys"."db_user_info") AND "grantor" <> 0 ORDER BY "name" ERROR = !SELECT: access denied for dump to table 'sys.db_user_info' So, my question to all subscribers: Does anybody managed to create another user with full rights to dump the database and when so, how? Any advice is greatly apprecitated. Best regards Klaus Kruse -- Corpex Internet GmbH * Schauenburgerstrasse 6 * D-20095 Hamburg Tel: +49 40 822268-0 * Fax: +49 40 822268-100 * http://www.corpex.de/ HRB 78752, Amtsgericht Hamburg, Sitz: Hamburg, USt.-Id: DE 213001412 Geschäftsführer: Daniel Hanelt

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Multi-column update based on joined table
by Lee Hachadoorian 10 Dec '13

10 Dec '13

I need to update multiple columns (~250) from one table to another based on a two-column key. In Postgres I would write this using the FROM clause, but since MonetDB doesn't support the FROM clause, I've successfully updated one column with: UPDATE census.acs2010_5yr SET b07401001 = ( SELECT CAST(b07401001 AS int) FROM acs2010_5yr.tmp_seq0001 WHERE acs2010_5yr.stusab = tmp_seq0001.stusab AND acs2010_5yr.logrecno = tmp_seq0001.logrecno ); My question is whether there is any benefit to writing a multiple column update into a single UPDATE statement: UPDATE target_table SET column1 = (SELECT column1 FROM source_table WHERE target_table.key = source_table.key), column2 = (SELECT column2 FROM source_table WHERE target_table.key = source_table.key), ..., columnN = (SELECT columnN FROM source_table WHERE target_table.key = source_table.key); On Postgres I believe the multi-column update using a table join would only have to do the sequential scan of each table once, but with the necessity of sub-selects in MonetDB, what is the backend doing? Is it already doing an index scan once for each row in the single column case, then doing it once for each row * column in the multi-column case? Best, --Lee -- Lee Hachadoorian Asst Professor of Geography, Dartmouth College http://freecity.commons.gc.cuny.edu/

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Moving monetdb data to another directory
by Rémi Charpentier 09 Dec '13

09 Dec '13

I am trying to change the default data directory of MonetDB. I installed monetdb using the ubuntu package, by default the data is stored in: /var/lib/monetdb I am running out of space, and I like to migrate the data to another folder. Does anyone know how to do that? I would welcome a solution that doesn't involve compiling monetdb from sources... Thanks in advance Remi

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Listing database objects in schema
by Lee Hachadoorian 06 Dec '13

06 Dec '13

Is there a way to list tables in a particular schema or even in all schemas? \d and \dt seem to only return user tables in the sys schema. Also, what does \ds return? I have \dS system tables \dt user tables \dv views \ds ????? \df functions \dn schemas Best, --Lee -- Lee Hachadoorian Asst Professor of Geography, Dartmouth College http://geospatial.commons.gc.cuny.edu/<http://freecity.commons.gc.cuny.edu/>

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