Scaling paginated list
----------------------
Key: CAY-999
URL: https://issues.apache.org/cayenne/browse/CAY-999
Project: Cayenne
Issue Type: Improvement
Components: Cayenne Core Library
Affects Versions: 3.0
Reporter: Andrus Adamchik
Assignee: Andrus Adamchik
An idea for scaling IncrementalFaultList to store massive amount of objects,
like hundreds of thousands.This pertains to the server-side
IncrementalFaultList. The problems to solve are the speed of the initial list
initialization and overall memory use.
1. Simplify ID representation:
Even unresolved lists can take significant amount of memory... Each unresolved
object slot currently stores a DataRow with N number of entries, where N is the
number of PK columns for the entity. I.e. most often than not - 1 entry. Here
is a memory use calculation for various representations of an unresolved entry,
based on a single int PK DbEntity.
a. DataRow - 120 bytes,
b. HashMap - 104 bytes,
c. Object[] - 32 bytes,
d java.lang.Integer - 16 bytes
[primitive int is even better, but it complicates the implementation, as we'd
need a parallel int[] (long[], double[], etc.) , so all in all we may get no
gain]
2. Swap out LRU pages
For the very large lists, it would make sense to un-fault resolved pages when
more pages are resolved , so that the list size doesn't grow beyond a certain
fixed amount, no matter how many pages are resolved. These parameters will have
to be configurable per query, as some users would prefer to keep the entire
thing...
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