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From "Yair Lenga (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-4555) Expand SYSCS_IMPORT_TABLE to accept CSV file with header lines
Date Mon, 20 Jun 2016 17:11:05 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15339922#comment-15339922

Yair Lenga commented on DERBY-4555:

Lot of good questions. I'll try to provide feedback, based on my own experience /requirements.

for #1 and #2.
import_data vs import_table. I think import_data is much more important. It is a super-set
of import_table. Import_table works only for few cases, when the external data is aligned
with the internal table structure - for example, when the data was exported from the table.
I would vote to focus only on import_data for the new functionality, and ignore import_table
at this time. In retrospect, I should have highlighted this priorities in the ticket.

For name matching. I suggest EXACT match on column names in the CSV. Most users of this extension
are going to be to bring in data from generated in another system. The system that generate
data in known pattern. Also, for data export, it is common practice to avoid using ALL special
characters in the column heading row, as many systems will fail to process the data. Including
support for special characters, quoting, etc. require lot of work, and brings mostly risk,
and complexity. In short, lot of downside, almost no upside.

I would admit that part of my preference toward a minimal solution that address my own situation
is that I hope to see the fix getting released in few months, minimizing the change that it
will get delayed due to quality issues.

Thanks for your effort! Yair.

> Expand SYSCS_IMPORT_TABLE to accept CSV file with header lines
> --------------------------------------------------------------
>                 Key: DERBY-4555
>                 URL: https://issues.apache.org/jira/browse/DERBY-4555
>             Project: Derby
>          Issue Type: Improvement
>          Components: Miscellaneous
>            Reporter: Yair Lenga
>            Assignee: Danoja Dias
>         Attachments: NoVarargs.diff, Varargs.diff, addNewSystemProcedure_1.diff, gotException.diff,
hardCoded.diff, latest.diff, noHeaderLines.csv, petlist.csv, petlist.csv, petlist.csv, repro.java,
repro.java, repro.java, skipHeaders.diff
> The SYSCS_IMPORT_TABLE (and SYSCS_IMPORT_DATA) function allow import of data from external
resources. In general, they can process CSV files that created with various tools - with one
exception: the header line.
> While there is no accepted standard, most tools will include a header line in the CSV
file with column names. This convention is supported in Excel and many other tools.
> My Request: extend the SYSCS_IMPORT_TABLe and SYSCS_IMPORT_DATA (and other related procedures)
to include an extra indicator for the number of header lines to be ignored.
> As an extra bonus it will be help is the SYSCS_IMPORT_DATA will accept column names (instead
of column indexes) in the 'COLUMNINDEXES' arguments. E.g., it should be possible to indicate
COLUMNINDEXES of '1,3,sales,5,'. This feature will make it significantly easier to handle
cases where the external input files is extended to include additional columns.

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