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Posted to jira@arrow.apache.org by "Neal Richardson (Jira)" <ji...@apache.org> on 2020/12/21 20:44:01 UTC
[jira] [Resolved] (ARROW-10642) [R] Can't get Table from
RecordBatchReader with 0 batches
[ https://issues.apache.org/jira/browse/ARROW-10642?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Neal Richardson resolved ARROW-10642.
-------------------------------------
Resolution: Fixed
Issue resolved by pull request 8956
[https://github.com/apache/arrow/pull/8956]
> [R] Can't get Table from RecordBatchReader with 0 batches
> ---------------------------------------------------------
>
> Key: ARROW-10642
> URL: https://issues.apache.org/jira/browse/ARROW-10642
> Project: Apache Arrow
> Issue Type: Bug
> Components: R
> Affects Versions: 2.0.0
> Environment: > sessionInfo()
> R version 4.0.3 (2020-10-10)
> Platform: x86_64-pc-linux-gnu (64-bit)
> Running under: Debian GNU/Linux 10 (buster)
> Matrix products: default
> BLAS: /usr/lib/x86_64-linux-gnu/openblas/libblas.so.3
> LAPACK: /usr/lib/x86_64-linux-gnu/libopenblasp-r0.3.5.so
> locale:
> [1] LC_CTYPE=C.UTF-8 LC_NUMERIC=C LC_TIME=C.UTF-8
> [4] LC_COLLATE=C.UTF-8 LC_MONETARY=C.UTF-8 LC_MESSAGES=C.UTF-8
> [7] LC_PAPER=C.UTF-8 LC_NAME=C LC_ADDRESS=C
> [10] LC_TELEPHONE=C LC_MEASUREMENT=C.UTF-8 LC_IDENTIFICATION=C
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
> other attached packages:
> [1] bigrquery_1.3.2 bigrquerystorage_0.1.0
> loaded via a namespace (and not attached):
> [1] Rcpp_1.0.5 cellranger_1.1.0 pillar_1.4.6
> [4] compiler_4.0.3 dbplyr_2.0.0 tools_4.0.3
> [7] odbc_1.3.0 getPass_0.2-2 digest_0.6.27
> [10] bit_4.0.4 gargle_0.5.0 jsonlite_1.7.1
> [13] memoise_1.1.0 lifecycle_0.2.0 tibble_3.0.4
> [16] pkgconfig_2.0.3 rlang_0.4.8 extraw_1.8.25
> [19] DBI_1.1.0 rstudioapi_0.13 curl_4.3
> [22] xml2_1.3.2 dplyr_1.0.2 httr_1.4.2
> [25] askpass_1.1 fs_1.5.0 generics_0.1.0
> [28] vctrs_0.3.5 hms_0.5.3 bit64_4.0.5
> [31] tidyselect_1.1.0 glue_1.4.2 data.table_1.13.2
> [34] R6_2.5.0 readxl_1.3.1 connect.cap_0.3.19
> [37] purrr_0.3.4 blob_1.2.1 magrittr_2.0.1
> [40] ellipsis_0.3.1 assertthat_0.2.1 keyring_1.1.0
> [43] arrow_2.0.0.20201117 openssl_1.4.3 crayon_1.3.4
> Reporter: Bruno Tremblay
> Priority: Minor
> Labels: pull-request-available
> Fix For: 3.0.0
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Objective is to build a 0 rows data.frame using an arrow schema field definition
>
>
>
> {code:java}
> #IPC stream containing only a schema
> stream<-as.raw(c(255,255,255,255,16,1,0,0,16,0,0,0,0,0,10,0,12,0,6,0,5,0,8,0,10,0,0,0,0,1,3,0,12,0,0,0,8,0,8,0,0,0,4,0,8,0,0,0,4,0,0,0,4,0,0,0,160,0,0,0,92,0,0,0,48,0,0,0,4,0,0,0,128,255,255,255,0,0,1,5,20,0,0,0,12,0,0,0,4,0,0,0,0,0,0,0,176,255,255,255,7,0,0,0,82,69,80,79,78,83,69,0,168,255,255,255,0,0,1,5,20,0,0,0,12,0,0,0,4,0,0,0,0,0,0,0,216,255,255,255,6,0,0,0,68,69,84,65,73,76,0,0,208,255,255,255,0,0,1,5,24,0,0,0,16,0,0,0,4,0,0,0,0,0,0,0,4,0,4,0,4,0,0,0,8,0,0,0,68,65,84,65,84,89,80,69,0,0,0,0,16,0,20,0,8,0,6,0,7,0,12,0,0,0,16,0,16,0,0,0,0,0,1,7,36,0,0,0,20,0,0,0,4,0,0,0,0,0,0,0,8,0,12,0,4,0,8,0,8,0,0,0,38,0,0,0,9,0,0,0,8,0,0,0,77,65,67,84,65,95,73,68,0,0,0,0,0,0,0,0))
> readr <- RecordBatchStreamReader$create(stream)
> readr$read_table()
> # Error in Table__from_RecordBatchStreamReader(self) :
> # Invalid: Must pass at least one record batch or an explicit Schema
> # Now trying to be too clever
> tb <- Table$create(data.frame(), schema = readr$schema)
> dtf <- as.data.frame(tb)
> # This will crash you R session
> {code}
>
>
> Tested on nightly, same behavior. It's borderline a bug / feature request, but to be a drop in replacement for some DBI methods, it needs to be able to build 0 rows data.frame with the correct class for each column.
>
> Thank you and have a nice day.
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