September 2020 - users-list

Default username and password: documented?
by Stefan Manegold 14 Sep '20

14 Sep '20

Hi, I just realize that, while the default (system-/admin-)username and password for a newly generated database in MonetDB are well known in the experienced MonetDB community, where do novice users find this information? I cannot find any explicit (or at least implicit?) documentation of this information, but maybe it's just that I fail to search properly? Any help is highly appreciated! Thanks! Best, Stefan -- | Stefan.Manegold(a)CWI.nl | DB Architectures (DA) | | www.CWI.nl/~manegold/ | Science Park 123 (L321) | | +31 (0)20 592-4212 | 1098 XG Amsterdam (NL) |

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Why MonetDB uses Materialization
by Amit Pandey 11 Sep '20

11 Sep '20

Hey All, Thanks for the great open source project. So while going through some materials in a CMU DB course I saw it mentioned that MonetDB uses full materialization, and this is a bit weird since in c-store potentially scanning a billion columns a full materialization may take a lot of time and the classic volcano model might be better. Can you guys please explain the rationale ? These are the slides :- https://15445.courses.cs.cmu.edu/fall2019/slides/12-queryexecution1.pdfMone… is mentioned in Slide 11. Thanks and Regards

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Bad query performance after lots of updates
by Daniel Glöckner 01 Sep '20

01 Sep '20

Hi, select count(*) from table where field = 'some value'; --> a few ms update table set field = 'value'; --> update 2 million rows out of 1 billion rows select count(*) from table where field = 'some value'; --> almost a minute :( Analyze did not help and sys.vacuum could not be used as the table has indexes (foreign key). Re-starting the DB helped ;) What's the recommended way to make MonetDB perform well after lots of updates? Kind regards, Daniel

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compilers
by Roberto Cornacchia 01 Sep '20

01 Sep '20

Hi, I was wondering whether anyone has run any benchmarks with MonetDB for testing the effect of compilation options. For example, any combination of * gcc vs clang * -O1 vs -O2 vs -O3 * -march and -mtune I am actually planning to do this myself, but knowing about any previous evidence (even anecdotal) would be helpful. Cheers, Roberto

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