Group indices description can be found here [1]. Please, check if you read docs for your ignite version, as configuration for ignite 1.x and 2.0 can differs. Group indices in Ignite a similar to composite or multi-column indixes in databases.
Yes, it is work that way. Group index for (groupFiled, timestampField) should be helpful. You can try to use EXPLAIN comand to check if correct index is in use. [1] https://apacheignite.readme.io/docs/indexes#section-group-indexes On Fri, May 5, 2017 at 8:17 PM, Guillermo Ortiz <konstt2...@gmail.com> wrote: > > > If I have two single indices to query: > > select * table a,b where a=1 and b=2 > > it doesn't work pretty good and I have to create a group index, how is > that possible? how does group indices work? > > Similar to this: > > select max(timestampField) > from myTable > group by groupField > > I have a index by groupField what it means that it should be really fast > to make the group and later make a partial map to find in each node the max > of the subset of data to merge the final submax and get the final result in > a "reduce" task after sending data through network. Is it how does it work? > This query it's really slow, I don't know if I created an index by > timestampField I would get better performance, but it doesn't too much > sense to create a index with a timestampField where there aren't too row > with the same value in a table with 250M rows.... > Any advice about this query? > -- Best regards, Andrey V. Mashenkov
