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https://issues.apache.org/jira/browse/ARROW-18113?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17634647#comment-17634647
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Percy Camilo Triveño Aucahuasi commented on ARROW-18113:
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??Sounds reasonable to me, at first glance. Maybe leave behind a {{using
CacheOptions = CoalesceOptions}} for compatibility (can you deprecate a
{{using}} declaration?)??
David, I think we can deprecate it (in case we choose to rename&move it).
??So if we add a _ReadManyAsync_ then I think it should not have a cache
options parameter. Instead that should be a property of the filesystem if it
needs to be configurable.??
Weston, yes initially I thought that _CoalesceOptions_ would be part of
_arrow::io::IOContext_ (as an attribute) and _ReadManyAsync_ could use/pass the
_CoalesceOptions_ to the filesystem. But it make sense to let the filesystem
handle all of that, so in that case:
# we still may choose to rename _arrow::io::CacheOptions_ to
{_}arrow::io::{_}{_}CoalesceOptions{_} and move it into {_}interfaces.h{_}, so
each filesystem's ctor will require {_}arrow::io::CoalesceOptions{_}.
# or we just can include _caching.h_ in every filesystem declaration without
changing/renaming _arrow::io::CacheOptions_ (so each filesystem's ctor will
require {_}arrow::io::{_}{_}CacheOptions{_})
Let me know which one sounds better to you, thanks.
> Implement a read range process without caching
> ----------------------------------------------
>
> Key: ARROW-18113
> URL: https://issues.apache.org/jira/browse/ARROW-18113
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Percy Camilo Triveño Aucahuasi
> Assignee: Percy Camilo Triveño Aucahuasi
> Priority: Major
>
> The current
> [ReadRangeCache|https://github.com/apache/arrow/blob/e06e98db356e602212019cfbae83fd3d5347292d/cpp/src/arrow/io/caching.h#L100]
> is mixing caching with coalescing and making difficult to implement readers
> capable to really perform concurrent reads on coalesced data (see this
> [github
> comment|https://github.com/apache/arrow/pull/14226#discussion_r999334979] for
> additional context); for instance, right now the prebuffering feature of
> those readers cannot handle concurrent invocations.
> The goal for this ticket is to implement a similar component to
> ReadRangeCache for performing non-cache reads (doing only the coalescing part
> instead). So, once we have that new capability, we can port the parquet and
> IPC readers to this new component and keep improving the reading process
> (that would be part of other set of follow-up tickets). Similar ideas were
> mentioned here https://issues.apache.org/jira/browse/ARROW-17599
> Maybe a good place to implement this new capability is inside the file system
> abstraction (as part of a dedicated method to read coalesced data) and where
> the abstract file system can provide a default implementation.
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