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From "ASF GitHub Bot (JIRA)" <>
Subject [jira] [Commented] (NIFI-2712) Database Fetch processors' max-value columns don't work as expected
Date Tue, 06 Sep 2016 20:54:21 GMT


ASF GitHub Bot commented on NIFI-2712:

Github user asfgit closed the pull request at:

> Database Fetch processors' max-value columns don't work as expected
> -------------------------------------------------------------------
>                 Key: NIFI-2712
>                 URL:
>             Project: Apache NiFi
>          Issue Type: Bug
>            Reporter: Matt Burgess
>            Assignee: Matt Burgess
> Currently, for QueryDatabaseTable and GenerateTableFetch, the user can enter any number
of maximum-value columns, which are used to generate a SQL query that will fetch all records
whose values are greater than the last-observed maximum values for those columns.
> However this makes multiple max-value columns not very useful, since they will both have
to increase in lockstep or records will be lost/skipped. In such a case, using one or the
other (but not both) would suffice, making multiple max-value columns useless.
> The more likely use case is that there are multiple columns whose values are strictly
increasing, but at different rates. This is common with very large tables where a column could
be for "date_created" and also a "bucket number" that strictly increases once a day. Queries
for a day's worth of data are more efficient if they can be filtered on "bucket" (in this
case), then on timestamp. However the generated SQL queries would have to reflect that "bucket"
may remain the same as timestamp is increasing, but once the bucket value has increased, then
only the (new) timestamps for that bucket should be fetched.

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