[jira] [Commented] (ARROW-10406) [Format] Support dictionary replacement in the IPC file format

["Neal Richardson (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-10406?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17259222#comment-17259222 ] 

Neal Richardson commented on ARROW-10406:
-----------------------------------------

The problem here was that, due to the way the chunked CSV reading handles dictionary encoding, I couldn't read a CSV and write it to Feather/Parquet, which seems like a critical failing.

> [Format] Support dictionary replacement in the IPC file format
> --------------------------------------------------------------
>
>                 Key: ARROW-10406
>                 URL: https://issues.apache.org/jira/browse/ARROW-10406
>             Project: Apache Arrow
>          Issue Type: Wish
>          Components: Format
>            Reporter: Neal Richardson
>            Priority: Major
>
> I read a big (taxi) csv file and specified that I wanted to dictionary-encode some columns. The resulting Table has ChunkedArrays with 1604 chunks. When I go to write this Table to the IPC file format (write_feather), I get an error: 
> {code}
>   Invalid: Dictionary replacement detected when writing IPC file format. Arrow IPC files only support a single dictionary for a given field accross all batches.
> {code}
> I can write this to Parquet and read it back in, and the roundtrip of the data is correct. We should be able to do this in IPC too.



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