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https://issues.apache.org/jira/browse/HIVE-8485?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14290065#comment-14290065
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Sushanth Sowmyan commented on HIVE-8485:
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[~ctang.ma] : Thanks for your comment! I considered auto-enabling this flag if
we detect oracle, but I think we will wind up having too many corner cases of
if-this-then-that in our code if we go down that path, and having a config
variable that we simply ask all oracle users to set is cleaner, I thought.
Also, with this patch, Oracle also does "work" out of the box, it just chooses
the strategy of trimming by default, as is done in all other dbs.
Also, if we wanted to support nulls inside the maps, that would be a change in
hive behaviour (for the better, I'd think, but a behaviour change nonetheless)
if we supported nulls. We'd have to handle escaping over thrift maps, but it
could be done.
Multiple spaces already work and is valid, just maybe not for a delim
parameter, but there's nothing stopping a user from having an arbitrary other
parameter be multiples of spaces, either in oracle or elsewhere.
> HMS on Oracle incompatibility
> -----------------------------
>
> Key: HIVE-8485
> URL: https://issues.apache.org/jira/browse/HIVE-8485
> Project: Hive
> Issue Type: Bug
> Components: Metastore
> Environment: Oracle as metastore DB
> Reporter: Ryan Pridgeon
> Assignee: Chaoyu Tang
> Attachments: HIVE-8485.2.patch, HIVE-8485.patch
>
>
> Oracle does not distinguish between empty strings and NULL,which proves
> problematic for DataNucleus.
> In the event a user creates a table with some property stored as an empty
> string the table will no longer be accessible.
> i.e. TBLPROPERTIES ('serialization.null.format'='')
> If they try to select, describe, drop, etc the client prints the following
> exception.
> ERROR ql.Driver: FAILED: SemanticException [Error 10001]: Table not found
> <table name>
> The work around for this was to go into the hive metastore on the Oracle
> database and replace NULL with some other string. Users could then drop the
> tables or alter their data to use the new null format they just set.
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