Spring boot won't use hibernates default_batch_fetch_size

Question

Tried to configure hibernates default_batch_fetch_size through the spring application.yml. AFAIK the setting has the same effect as putting @BatchSize(size = xxx) annotations on all your entity-relationships.

I enabled spring.jpa.properties.hibernate.generate_statistics: true and logging accordingly and tried setting

spring:
  jpa:
    properties:
      hibernate:
        jdbc:
          batch_size: 100
          default_batch_fetch_size: 30

I also tried

spring:
  jpa:
    hibernate:
      ddl-auto: none
      default_batch_fetch_size: 30

but that configuration property doesn't seem to exist at all.

Resulting Logs show that hibernate won't fetch collections batched, but N+1 (FetchMode is not specified - thus the default @Fetch(FetchMode.SELECT) is used - and I don't want to change that).

I thought it's at least somewhat related. i.e., see : https://stackoverflow.com/a/32456516/314089. But I agree that it's not necessarily directly linked or a definitive answer for the N+1-SELECT problem. — icyerasor, Aug 25 '20 at 13:15

score 2 · Answer 1 · answered Aug 24 '20 at 13:08

2

Turns out I mixed up where to put the property-config. The right path is something like this:

spring:
  jpa:
    properties:
      hibernate:
        default_batch_fetch_size: 30
        jdbc:
          batch_size: 100

answered Aug 24 '20 at 13:08

icyerasor

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Spring boot won't use hibernates default_batch_fetch_size

1 Answers1