Hi Macarse, I had a look at this and here are some comments:
Running your code with default parameters on a 1.6 JVM about 50% of the time will be spent in garbage collection. Giving the JVM "-Xms128M -Xmx128M" will cut the variation of the query times from 2500-3000 ms down to 1300-1600 ms (removing most of the GC time). I am sure it would be possible to get the times down even further since this is to much of a "micro benchmark" for Hotspot to kick in. The use of String.format to format the Customers/Order/Item objects to a string similar to the SQL select output also takes some time. In most use-cases there is no need to work with your data in a string representation. You also run everything in the same transaction. I tried getting some information on transaction and what isolation level the insert/query you where running on the relational database was using but could not see any info about it. If you split the create/insert part in one transaction and run the query in a separate transaction the query should drop down to about 350ms (that is with 128M heap and no String.format). Finally 80ms for the select is quite impressive, almost too good to be true. I would say just transforming an in memory representation of Item/Order/Customer objects to a string representation will take longer. Was the full result set from the SQL query traversed? Also many relational databases keep an "exact query match cache" meaning if you run the exact same query twice the second run will not perform any real work. This can be avoided by running an update on the tables participating in the query. Regards, Johan On Sun, Jun 21, 2009 at 6:04 AM, Macarse<[email protected]> wrote: > I gave up my count(*) test and try something that hurts relational databases! > > //Data inserted > So I have 4 persons (Charly, maxi, juani, laura) who buys 2 movies > each in a for loop. > That for loop runs 1k times. > > //SQL > Database schema > http://code.google.com/p/grafos2009/source/browse/trunk/mysql/video/create.sql > > Inserts are done with a python script that creates the inserts: > http://code.google.com/p/grafos2009/source/browse/trunk/mysql/video/test.py > > Query to be done: > http://code.google.com/p/grafos2009/source/browse/trunk/mysql/video/queries.sql > > > //neo4j > http://code.google.com/p/grafos2009/source/browse/trunk/src/main/java/org/seminario/Seminario.java > > > SQL big select: > 8000 rows in set (0.08 sec) > > neo4j 8000 lines: > 2950 ms. > > Then I tried sql with 10k loop, and gave me (0.94 sec). > > I can't beat sql :( > Comments are welcomed! > > > PS: I know the select in the db is not the same as I do with neo4j, > but calls my attention that big difference. _______________________________________________ Neo mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
