Le sam. 15 juin 2019 à 20:29, Simon Slavin <slav...@bigfraud.org> a écrit :
> On 15 Jun 2019, at 2:42pm, Dan Kaminsky <dan.kamin...@medal.com> wrote: > > [about the 32676 hard limit on the number of columns in a table] > > > I spent quite a bit of time hacking large column support into a working > > Python pipeline, and I'd prefer never to run that in production. > > Converting this compile time variable into a runtime knob would be > > appreciated. > > Something you should know about SQLite is that if it needs to find the > 2001st column of a row it has to read the entire row from storage and walk > through all 2000 columns before the one it wants. So both storing and > recalling data in wide tables is very inefficient. > > To compensate for this problem, which occurs in many SQL engines, you can > turn your wide table into a thin table (key/value pairs) by adding the > column name to the key. SQLite is extremely good at handling tall thin > tables. > > If you think about what you're really doing with your data you're find > that although it's classically drawn out as a huge 2D grid, the data is > closer to an Entity–attribute–value model, and more suited to a tall table > with a long key. > Isn't this a use-case of LSM extension? Thanks, Amirouche _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
