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Subject [GitHub] [ignite] dmelnichuk commented on issue #6553: IGNITE-11854 Fix performance problem when creating arrays
Date Wed, 05 Jun 2019 14:00:53 GMT
dmelnichuk commented on issue #6553: IGNITE-11854 Fix performance problem when creating arrays
URL: https://github.com/apache/ignite/pull/6553#issuecomment-499095495
   > I've tried the patch and it looks like something is still wrong.
   > Is it the expected behavior?
   Well, there is always a room for improvement, but to be able to deliver `pyignite` in reasonable
time, I started on the following premises:
   - all Ignite data types, that represent signed integers (`Byte`, `Short`, `Integer`, and
`Long`) must be represented with Python boundless integer (`int`) type,
   - implementation of sequential Ignite data types (arrays, `Map`, `Sequence`) must be based
on the corresponding singular types' representations. For example, `ByteArrayObject` uses
internal methods of `ByteObject`.
   Both measures have simplified the code greatly. So, yes, it is the expected behavior: to
create an array, client really should create each of its element iteratively, as if building
it from abstract `Iterable[int]`.
   >In case yes, what can be solution to put big binary data (more than 100MB ) into Ignite
using thin python client?
   I must admit, I don't have a simple solution to this problem. I think it may be possible
to provide a fast method of creating `ByteArray` from `bytearray` as an in situ optimization,
still maintaining its default `Iterable[int]` mapping. Retrieving `ByteArray` from Ignite
as `bytearray` will definitely break the user API though.
   But I can't help but wonder: is storing/retrieving large amounts of unstructured data into/from
Ignite is really a case? Especially with Python client? Python is not particularly famous
for its byte stream processing speed.
   > Also, I've noticed that instead of retrieving bytearray I'm getting a list of ints
when calling `cache.get()` and some of the values are negative? Is it a defect?
   Not at all, it is an expected behavior. As I said earlier, Java's `Byte` is a signed integer
(-128…127), while Python's `bytearray` consists of unsigned elements (0…255). You are
not losing data; it is just a matter of its representation.

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