Thanks, Wes. I was able to get the setup you outlined working as long as I explicitly communicate the location of the footer to processes wanting to read the table (I'm not sure if there's a better way of doing this). One other thing, though, that I would ultimately like to do is share a table that is conceptually growing. Is that something that arrow is intended for?
I see in the code that a lot of the table-related data structures are immutable and that the footer is written only on close, so perhaps not. But, any thoughts on a use case like that would be appreciated. -Mike -----Original Message----- From: Wes McKinney [mailto:wesmck...@gmail.com] Sent: Wednesday, May 10, 2017 22:11 To: dev@arrow.apache.org Subject: Re: list scope question hi Mike, I recommend using record batches along with io::MemoryMappedFile. You can write the table with ipc::FileWriter: https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_apache_arrow_blob_master_cpp_src_arrow_ipc_writer.h-23L111&d=DwIFaQ&c=f5Q7ov8zryUUIGT55zpGgw&r=p7uiAfJkXEwbVhZPqB-VxtsgxuGNpO5tGgnMUX3wqrPAIvdxhcKmn9kvZiXDziBQ&m=pWtlkbDLKO7PWTrI6MPiTzAuUgTWYLSRraZBy7KPCYA&s=Ud95KVEwn_XX3LwfEKTLH7nXvKGmOLhYnUu09ZrLyOg&e= and then read it with ipc::FileReader. If you use MemoryMappedFile, then the read will be zero-copy (no memory allocated), so ideal for a multiple-process shared memory setting. You can use one large record batch or multiple smaller record batches. Let us know if you run into issues. Thanks Wes On Wed, May 10, 2017 at 7:06 PM, Katelman, Michael <michael.katel...@cubistsystematic.com> wrote: > Great! > > What I'd like to do is create a table that can be shared among multiple > processes. I see, e.g., this in the comments where RecordBatch is defined: > > // A record batch is a simpler and more rigid table data structure > intended for // use primarily in shared memory IPC. It contains a > schema (metadata) and a // corresponding sequence of equal-length > Arrow arrays class ARROW_EXPORT RecordBatch { > > But I wasn't entirely sure what the author had in mind. > > -Mike > > -----Original Message----- > From: Jason Altekruse [mailto:altekruseja...@gmail.com] > Sent: Wednesday, May 10, 2017 17:59 > To: dev@arrow.apache.org > Subject: Re: list scope question > > I think we opted to not create a user list yet, as using arrow is likely > going to require some willingness to poke around in the library until we can > fill out the docs and some more complete example usages. So as far as I know > this is the place to ask, what were you looking to do? > > On Wed, May 10, 2017 at 2:28 PM, Katelman, Michael < > michael.katel...@cubistsystematic.com> wrote: > >> Is there a good place for user-oriented arrow questions and discussions? >> (my apologies in advance if this isn't the appropriate venue) >> >> -Mike >> >> >> >> >> >> DISCLAIMER: This e-mail message and any attachments are intended >> solely for the use of the individual or entity to which it is >> addressed and may contain information that is confidential or legally >> privileged. If you are not the intended recipient, you are hereby >> notified that any dissemination, distribution, copying or other use >> of this message or its attachments is strictly prohibited. If you >> have received this message in error, please notify the sender >> immediately and permanently delete this message and any attachments. >> >> >> >> > > > > > > DISCLAIMER: This e-mail message and any attachments are intended solely for > the use of the individual or entity to which it is addressed and may contain > information that is confidential or legally privileged. If you are not the > intended recipient, you are hereby notified that any dissemination, > distribution, copying or other use of this message or its attachments is > strictly prohibited. If you have received this message in error, please > notify the sender immediately and permanently delete this message and any > attachments. > > >
