[
https://issues.apache.org/jira/browse/NIFI-2881?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15820025#comment-15820025
]
ASF GitHub Bot commented on NIFI-2881:
--------------------------------------
Github user ijokarumawak commented on a diff in the pull request:
https://github.com/apache/nifi/pull/1407#discussion_r95719637
--- Diff:
nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/QueryDatabaseTable.java
---
@@ -127,6 +129,7 @@
.defaultValue("0")
.required(true)
.addValidator(StandardValidators.NON_NEGATIVE_INTEGER_VALIDATOR)
+ .expressionLanguageSupported(true)
.build();
public QueryDatabaseTable() {
--- End diff --
This is just a question out of curiosity, QueryDatabaseTable supports
dynamic properties `Initial Max Value`, but GenerateTableFetch doesn't. As my
understanding, QueryDatabaseTable and GenerateTableFetch are identical except
the former execute SQL query while the latter generate flow files containing
SQL. Initial Max Value dynamic property would be useful for GenerateTableFetch,
too.
Also wondering how it will work if table name is specified by EL.
> Allow Database Fetch processor(s) to accept incoming flow files and use
> Expression Language
> -------------------------------------------------------------------------------------------
>
> Key: NIFI-2881
> URL: https://issues.apache.org/jira/browse/NIFI-2881
> Project: Apache NiFi
> Issue Type: Improvement
> Components: Extensions
> Reporter: Matt Burgess
> Assignee: Matt Burgess
>
> The QueryDatabaseTable and GenerateTableFetch processors do not allow
> Expression Language to be used in the properties, mainly because they also do
> not allow incoming connections. This means if the user desires to fetch from
> multiple tables, they currently need one instance of the processor for each
> table, and those table names must be hard-coded.
> To support the same capabilities for multiple tables and more flexible
> configuration via Expression Language, these processors should have
> properties that accept Expression Language, and GenerateTableFetch should
> accept (optional) incoming connections.
> Conversation about the behavior of the processors is welcomed and encouraged.
> For example, if an incoming flow file is available, do we also still run the
> incremental fetch logic for tables that aren't specified by this flow file,
> or do we just do incremental fetching when the processor is scheduled but
> there is no incoming flow file. The latter implies a denial-of-service could
> take place, by flooding the processor with flow files and not letting it do
> its original job of querying the table, keeping track of maximum values, etc.
> This is likely a breaking change to the processors because of how state
> management is implemented. Currently since the table name is hard coded, only
> the column name comprises the key in the state. This would have to be
> extended to have a compound key that represents table name, max-value column
> name, etc.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
