Re: [hibernate-dev] Where are the batched fetch statements generated?

Just to clarify... (3) is not building the entire statement. Most of the statement can be pre-built. It just needs to append the proper IN-condition On Thu 01 Nov 2012 09:30:41 AM CDT, Steve Ebersole wrote: > Maybe its best to make this configurable too? > > I can see 3 selections: > 1) current algorithm - the current code as is > 2) current size break down but with padding - the current code except > selecting the next higher batch size and padding extras (current code > selects next smaller size, iteratively) > 3) dynamic - dynamically build the batch statement > > wdyt? > > On Tue 30 Oct 2012 02:28:31 PM CDT, Steve Ebersole wrote: >> Well the other option is to not pre-build/cache the statements for the >> batch sizes. That would free up memory as well as reduce the number >> of queries to just one, with the offset being the need to build the >> SQL dynamically (although most of it could be built up front). >> >> >> On 05/08/2012 02:06 AM, Clemens Eisserer wrote: >>> Hi Guenther, >>> >>>>>> Is it possible to disable prepared statement caching for batched >>>>>> fetching, so I end up with a single query in the < >>>>>> default_batch_fetch_size case only >>instead of the >>>>>> fixed-size batch loading hibernate does by default? >>> >>>> I think the main reason for no feedback so far, is that nobody was >>>> able to understand this sentence. >>>> Usually 'prepared statement caching' is a synonym to 'prepared >>>> statement pooling' and is something which has to be provided by a >>>> connection-pool (or a jdbc-driver) and thus >>>> Hibernate does actually not implement any prepared statement >>>> cache/pooling. >>>> Can you please explain what you intend under 'prepared statement >>>> caching'? >>>> Can you also please try to better explain the second part of your >>>> sentence? >>> >>> Sorry for beeing that cryptic, I will try to rephrase it: >>> >>> When Hibernate does batch-fetching, it generates PreparedStatements >>> for certain batch sizes - for a batch_size of 50, the prepared >>> statements for batch-sizes will have the following sizes: >>> [1,2,3,4,5,6,7,8,9,10,12,25,50]. When e.g. a batch of size 13 should >>> be fetched, because of the fixed size of the prepared statements, 3 >>> queries are issued for batch-fetching, although 13 <= 50. In this case >>> the 3 batches would be of the size 13 = 8 + 4 + 1. >>> In a latency bound (between db and application) environment, this >>> serverly hampers response time - instead of a single round-trip to do >>> the batched fetch, Hibernate requires 3. >>> (subselect can't be used in my case, because my queries are already >>> rather complex, and the added complexity confuses the DBs query >>> planner too much) >>> >>> What I did in this case (only for integer PKs) is to pad up to the >>> next batch size with a non-existant PK. >>> So, for the example mentioned above, I can use the PreparedStatement >>> with size 25, and insert padding from 14-25, which will make the query >>> slightly more inefficient but avoid 2 additioan round-trips. >>> >>> - Clemens >>> _______________________________________________ >>> hibernate-dev mailing list >>> hibernate-dev(a)lists.jboss.org >>> https://lists.jboss.org/mailman/listinfo/hibernate-dev >>> >> > > -- > steve(a)hibernate.org > http://hibernate.org -- steve(a)hibernate.org http://hibernate.org