1

I have a requirement in which I am retrieving values in one Reader of the Step using SQL statements and doing the same request in next reader.

I do not want to make another request if the data is already fetched in the First reader and pass that collection (possibly a HashMap) to next step. For this I have gone through the following link on SO : How can we share data between the different steps of a Job in Spring Batch?

In many of the comments it is mentioned that 'data must be short'.

Also it is mentioned in one response that: these contexts are good to share strings or simple values, but not for sharing collections or huge amounts of data.

By passing that HashMap, I believe it automatically infers that the reference of the HashMap will be passed.

It would be good to know the possible consequences of passing it before hand and any better alternative approach.

Deep
  • 929
  • 2
  • 16
  • 32
  • 1
    That thread is outmoded. Which version are you currently using? – Andrew Tobilko Nov 11 '18 at 18:07
  • @AndrewTobilko : it is 3.0.7 – Deep Nov 11 '18 at 18:11
  • I am guessng the problem is that Spring Batch saves its state in a table during execution - and this Map of yours would be saved as part of that context. If the data in the map is large enough, it could be more than the column in the table can hold (by default, anyway). IIRC, in one of our applications we just resized that column larger than it is by default... – moilejter Nov 11 '18 at 19:12

1 Answers1

0

Passing data between step is indeed done via the execution context. However, you should be careful about the size of data you put in the execution context as it is persisted between steps.

I do not want to make another request if the data is already fetched in the First reader and pass that collection (possibly a HashMap) to next step

You can read the data from the database only once and put it in a cache. The second reader can then get the data from the cache. This would be faster that reading the data from the database a second time.

Hope this helps.

Mahmoud Ben Hassine
  • 28,519
  • 3
  • 32
  • 50