我相信它应该非常快(30-50毫秒),在你的情况下,如果你试图在存储数据存储之后立即从数据存储获取实体,它应该不成问题。
您可以使用log4j并尝试输出持续时间的时间以了解需要多长时间。
实施例,
INFO:时间持续数据存储区:38毫秒
# A default log4j configuration for log4j users.
#
# To use this configuration, deploy it into your application's WEB-INF/classes
# directory. You are also encouraged to edit it as you like.
# Root logger option
log4j.rootLogger=INFO
# Configure the console as our one appender
log4j.appender.A1=org.apache.log4j.ConsoleAppender
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%d{HH:mm:ss,SSS} %-5p [%c] - %m%n
# tighten logging on the DataNucleus Categories
log4j.category.DataNucleus.JDO=WARN, A1
log4j.category.DataNucleus.Persistence=WARN, A1
log4j.category.DataNucleus.Cache=WARN, A1
log4j.category.DataNucleus.MetaData=WARN, A1
log4j.category.DataNucleus.General=WARN, A1
log4j.category.DataNucleus.Utility=WARN, A1
log4j.category.DataNucleus.Transaction=WARN, A1
log4j.category.DataNucleus.Datastore=WARN, A1
log4j.category.DataNucleus.ClassLoading=WARN, A1
log4j.category.DataNucleus.Plugin=WARN, A1
log4j.category.DataNucleus.ValueGeneration=WARN, A1
log4j.category.DataNucleus.Enhancer=WARN, A1
log4j.category.DataNucleus.SchemaTool=WARN, A1
之后立即获得Id是一个问题,但我不确定这个答案是什么,但是这里的信息支持这个答案,即这个Key可以立即使用 - 至少是使用DatastoreService.put()。我同意,因为需要构建Key https://developers.google.com/appengine/docs/java/javadoc/com/google/appengine/api/datastore/DatastoreService#,因此应该立即推出Id把%28com.google.appengine.api.datastore.Entity 29% – user1445967