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From Vladimir Ozerov <voze...@gridgain.com>
Subject Re: BinaryObject pros/cons
Date Fri, 28 Oct 2016 08:18:49 GMT

Currently null value is written as one byte, while zero value of long type
is written as 9 bytes. I want to improve that and write zeros as one byte
as well.

As per var-length encoding, I am strongly against it. It saves IO and
memory at the cost of CPU. If we encode numbers in this way we will
slowdown SQL (which is already not very fast, to be honest). Because
instead of a single read memory read, we will have to perform multiple
reads and then apply some mechanics to restore original value. We already
have such problem with Strings - Java stores them as UTF-16, but we encode
them as UTF-8. As a result every read of a string field in SQL results in
decoding overhead.


On Fri, Oct 28, 2016 at 6:07 AM, Valentin Kulichenko <
valentin.kulichenko@gmail.com> wrote:

> Cross-posting this to dev list.
> Vladimir,
> To be honest, I don't see much difference between null values for objects
> and zero values for primitives. From BinaryObject semantics standpoint,
> both are default values for corresponding types. These values will be
> returned from the BinaryObject.field() method regardless of whether we
> actually save then in the byte array or not. Having said that, why don't we
> just skip them during write?
> You optimization will be still useful though, because there are often a
> lot of ints and longs that are not zeros, but still small and can fit 1-2
> bytes. We already added such compaction in direct message marshaling and it
> reduced overall traffic by around 30%.
> -Val
> On Thu, Oct 27, 2016 at 2:21 PM, Vladimir Ozerov <vozerov@gridgain.com>
> wrote:
>> Hi,
>> I am not very concerned with null fields overhead, because usually it
>> won't be significant. However, there is a problem with zeros. User object
>> might have lots of int/long zeros, this is not uncommon. And each zero will
>> consume 4-8 additional bytes. We probably will implement special
>> optimization which will write such fields in special compact format.
>> Vladimir.
>> On Thu, Oct 27, 2016 at 10:55 PM, vkulichenko <
>> valentin.kulichenko@gmail.com> wrote:
>>> Hi,
>>> Yes, null values consume memory. I believe this can be optimized, but I
>>> haven't seen issues with this so far. Unless you have hundreds of fields
>>> most of which are nulls (very rare case), the overhead is minimal.
>>> -Val
>>> --
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>>> Sent from the Apache Ignite Users mailing list archive at Nabble.com.

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