Hi, Do you read all rows? Maybe creating an index, and using "order by" would help.
Regards, Thomas On Tuesday, November 24, 2015, Michaël Michaud <[email protected]> wrote: > Hello, > > Is there a way to avoid OutOfMemory with large "group by" queries. > I have a large table and want to group rows according to id column. > Here is a simple test case to reproduce the problem (I use H2GIS 1.2.3 > based on H2 1.4.188 because original query is a spatial query) > > jvm : -Xmx512M > > CREATE TABLE A(id integer); > @loop 20000000 INSERT INTO A VALUES (?/*rnd*/ / 10); > SELECT id, count(*) FROM A GROUP BY id LIMIT 1000; > -> OOM > > In my initial query, query is more complex, rows are more complex, > aggregate function is a spatial function... so that I reach OOM > with only 6M rows and as much as 16G. > > Thanks for your help and for a great software, > > Michaël > > > > > > -- > You received this message because you are subscribed to the Google Groups > "H2 Database" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <javascript:_e(%7B%7D,'cvml','h2-database%[email protected]');> > . > To post to this group, send email to [email protected] > <javascript:_e(%7B%7D,'cvml','[email protected]');>. > Visit this group at http://groups.google.com/group/h2-database. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "H2 Database" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/h2-database. For more options, visit https://groups.google.com/d/optout.
