Re: [hibernate-users] Newbie Performance Questions

Yeah. If you're doing something along the lines of createQuery("from Library library") and then accessing the colors of the library, it's definitely an N+1 selects problem. You can avoid this by doing a join-fetch ("from Library library join fetch library.colors color") or possibly by using the @BatchSize annotation. Best! *From:*Eric Kolotyluk [mailto:eric.kolotyluk@gmail.com] *Sent:* Sunday, August 14, 2011 10:22 PM *To:* Haswell, Joe *Subject:* Re: [hibernate-users] Newbie Performance Questions OK, please see the attachments. I am not really understanding how HQL transforms into SQL, as it was easy for me to write the SQL Cheers, Eric On 2011-08-14 9:14 PM, Haswell, Joe wrote: Can you include your entities? Thanks, Joe H. | HP Software *From:*hibernate-users-bounces@lists.jboss.org <mailto:hibernate-users-bounces@lists.jboss.org> [mailto:hibernate-users-bounces@lists.jboss.org] *On Behalf Of *Eric Kolotyluk *Sent:* Sunday, August 14, 2011 9:45 PM *To:* hibernate-users(a)lists.jboss.org <mailto:hibernate-users@lists.jboss.org> *Subject:* Re: [hibernate-users] Newbie Performance Questions I'm not sure, I' just using whatever the defaults are. The more I think of it the more I think the problem is that I am doing my iterations procedurally in Java, rather than declaratively in HQL. While I can use the following SQL query to get my results, I cannot figure out the corresponding HQL query. SELECT "Color"."name", "RepresentationLAB".coordinates_l, "RepresentationLAB".coordinates_b, "RepresentationLAB".coordinates_a FROM "ColorRepository"."Library", "ColorRepository"."Library_Color", "ColorRepository"."Color", "ColorRepository"."Color_Representation", "ColorRepository"."RepresentationLAB" WHERE "RepresentationLAB"."id" = "Color_Representation"."rightID" and "Color_Representation"."leftID" = "Color"."id" and "Color"."id" = "Library_Color"."rightID" and "Library_Color"."leftID" = "Library"."id" and "Library"."name" = 'PANTONE Goe coated' The HQL query I am trying follows, but when I run it nothing is returned String hql = "SELECT new com.kodak.vip.color.repository.SpotColor(" + "colors.name, " + "representationLAB.coordinates.l, " + "representationLAB.coordinates.a, " + "representationLAB.coordinates.b) " + "FROM " + "Library as library join library.colors as colors, " + "Color as color join color.representations as representations, " + "RepresentationLAB as representationLAB " + "WHERE " + "representationLAB.id = representations.id and " + "representations.id = color.id and " + "color.id = colors.id and " + "colors.id = library.id and " + "library.name = '" + getName() + "'"; Query query = hibernate.getCurrentSession().createQuery(hql); return query.list(); Which generates the following SQL Hibernate: select color2_."name" as col_0_0_, representa6_."coordinates_l" as col_1_0_, representa6_."coordinates_a" as col_2_0_, representa6_."coordinates_b" as col_3_0_ from "ColorRepository"."Library" library0_ inner join "ColorRepository"."Library_Color" colors1_ on library0_."id"=colors1_."leftID" inner join "ColorRepository"."Color" color2_ on colors1_."rightID"=color2_."id" cross join "ColorRepository"."Color" color3_ inner join "ColorRepository"."Color_Representation" representa4_ on color3_."id"=representa4_."leftID" inner join "ColorRepository"."Representation" representa5_ on representa4_."rightID"=representa5_."id" cross join "ColorRepository"."RepresentationLAB" representa6_ inner join "ColorRepository"."Representation" representa6_1_ on representa6_.id=representa6_1_."id" where representa6_.id=representa5_."id" and representa5_."id"=color3_."id" and color3_."id"=color2_."id" and color2_."id"=library0_."id" and library0_."name"='PANTONE Goe coated' Cheers, Eric On 2011-08-14 5:00 PM, Haswell, Joe wrote: Are the Library's colors lazily loaded? You could be encountering an N+1 selects issue. *From:*hibernate-users-bounces@lists.jboss.org <mailto:hibernate-users-bounces@lists.jboss.org> [mailto:hibernate-users-bounces@lists.jboss.org] *On Behalf Of *Eric Kolotyluk *Sent:* Sunday, August 14, 2011 5:11 PM *To:* hibernate-users(a)lists.jboss.org <mailto:hibernate-users@lists.jboss.org> *Subject:* [hibernate-users] Newbie Performance Questions I have been using Hibernate since January 2011, but more recently I am integrating things into some UI. For some context I have an application that deals with libraries of colors. Our current application stores the libraries in XML files under Castor on the local file system. A given library has 2,000 colors in it and takes maybe 200 ms to load. My JPA framework looks something like @Entity Library - m2m - @Entity Color - m2m - @Entity Representation (i.e. L*a*b*) In my application, loading from a PostgreSQL database via Hibernate the same data takes 1. 20 seconds to load with full logging enabled 2. 16 seconds to load with logging disabled 3. 4 seconds to reload a second time (probably due the default caching behavior) 4. 0.2 seconds from via SQL from PostgreSQL 5. 0.2 seconds to load from Castor 6. 0 seconds (usually) if I use SoftReferences to cache the data in memory Some of my questions are: 1. Is the performance I am seeing typical? Is it what most people would agree to expect from using Hibernate with a DBMS like PostgreSQL? 2. When logging is turned on, I see what looks like an obscene amount of SQL produced for only 2,000 colors. When logging is turned off, 16 seconds still seems like an awfully long time to load 2,000 color representations, where running an SQL query to extract the same data takes 203 ms. 3. What exactly is taking so long? Using Hibernate I basically load the library object, then iterate over all the colors it has, then for each color object I get the representation object and load the L*a*b* data into the UI. 4. Am I making some lame newbie mistake somewhere, and what would that mistake be? 5. Should I be formulating an appropriate HQL statement, similar to my SQL statement, and loading things that way? 6. Is there some documentation on using Hibernate with Graphical User Interfaces, or some best practices documentation somewhere? Cheers, Eric