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From "Matthew Jacobs (Code Review)" <>
Subject [Impala-CR](cdh5-trunk) Simplify creating external Kudu tables and add DROP DATABASE CASCADE
Date Mon, 25 Apr 2016 21:59:03 GMT
Matthew Jacobs has posted comments on this change.

Change subject: Simplify creating external Kudu tables and add DROP DATABASE CASCADE

Patch Set 7:

File fe/src/main/java/com/cloudera/impala/analysis/

Line 1: package com.cloudera.impala.analysis;
legal header
File fe/src/main/java/com/cloudera/impala/analysis/

Line 124:     return new EqualsBuilder()
File fe/src/main/java/com/cloudera/impala/analysis/

Line 151: getRowFormat
does this need to be public?

Line 152: rowFormat_ != null ? rowFormat_
        :         : fileFormat_ == THdfsFileFormat.TEXT ? RowFormat.DEFAULT_ROW_FORMAT : null;
can you change the first ternary to if/else for readability, and in case it is not null, can
you add a Precondition that fileFormat is TEXT?

Line 224: fileFormat_ != THdfsFileFormat.KUDU &&
        :         KuduTable.KUDU_STORAGE_HANDLER.equals(
        :             tblProperties_.get(KuduTable.KEY_STORAGE_HANDLER))
This allows the Kudu storage handler to be set if the fileFormat_ is KUDU. Is that what you

Line 237: fileFormat_ != THdfsFileFormat.KUDU
Following up on my comment from an earlier revision. If we don't check that this only holds
for external kudu tables, then it's valid to create a managed (non-external) kudu table without
columns defined, which we shouldn't allow. (Or perhaps there's something else that's failing
somewhere but it'd be harder to understand the issue.) I think we should just be handling
the isExternal_ here.

Line 298: throw new AnalysisException(String.format(
        :           "ROW FORMAT cannot be specified for file format %s.", fileFormat_));
can you check if ff != TEXT sooner to throw this, then same on the indentation for the bulk
of this fn

Line 308: tblProperties_
Re-analyze still seems broken...

Line 331: columnDefs_
In the case of reanalysis (reset() -> analysis()) we'll add duplicates of these dummy column
defs which I think would break  if we ever end up reanalyzing twice bc it'd have duplicate
col names.

I guess you can add it iff it's not already in there, but I think you'd have to walk through
the list since it's possible for users to specify the cols as well. (Or do you want to disallow

Line 335: keyCols
I think we might want some additional analysis on the keys, e.g., are the key cols valid cols?
File fe/src/main/java/com/cloudera/impala/catalog/delegates/

Line 160: Preconditions.checkState(
        :         cols.get(0).getName().equals(REQUIRED_THRIFT_COLUMN_DEF.getColName()));
I didn't think we prevented users from creating an external table with columns defined? In
fact, I was thinking you might want to do that so you can define a subset of the kudu columns,
perhaps. I guess based on the code below we just won't support it. That's fine, but maybe
we should throw an analysis exception in CreateTableStmt

Line 164: kuduTable.getSchema().getColumns()
do we know if this comes back in a consistent order? Given we flatten the names into a string
we may want to make sure it's a consistent order if we ever need to compare KEY_COLUMNS

Line 194: com.cloudera.impala.catalog.
I think you can remove the namespace as it's clear from l197 what's going on

Line 204:;
nit: just put this directly on l205 and save a line

Line 213:  
nit: space
(don't shoot the messenger!)
File fe/src/main/java/com/cloudera/impala/service/

Line 1126: s

Line 1131: If that's assumption isn't
This doesn't make sense. that's -> that?

Line 1121: // The use of DdlDelegates combined with the fact that the catalog is disconnected
         :     // from the source of truth, the Hive metastore, leads to some complications
         :     // If 'db' is null, that should mean either the database doesn't really exist
or the
         :     // database was created outside of Impala and the user didn't run "invalidate
         :     // metadata". If 'db' is not null, there still may be tables in the metastore
         :     // would require a DdlDelegate. Another scenarios is when the user creates
         :     // that reqire a DdlDelegate in Impala, then drops the database in Hive. Ideally
         :     // user visible result of DROP DATABASE CASCADE would be the same in any case.
         :     // best solution is probably to move the DdlDelegate functionality into Hive.
         :     // now Impala will assume that any table not in its cache also doesn't require
         :     // use of a DdlDelegate. If that's assumption isn't correct, the database will
         :     // be dropped in the metastore but the underlying data would remain.
this is getting big, how about creating a JIRA to track this Hive/Impala integration consideration.
I think it's worthwhile since field folks may need to think about this or encounter this,
so filing a JIRA now would be useful. Then we can put most of this text there and reference
the JIRA w/ just a brief comment.

Line 1132:     // be dropped in the metastore but the underlying data would remain.
Can you add that users can be sure to avoid this by calling refresh before dropping a database?

Line 1159: the user is expected to ALTER TABLE to either set the
         :       // table to UNMANAGED or set the format to one that doesn't require a delegate.
we should track this somehow so we can eventually get it in documentation. do you have a list
of usability/doc concerns? if not, it's probably worth starting something

Line 1541: setDistributeParams(distributeBy)
This is only relevant to Kudu, so it'd be nice if we could have the KuduDdlDelegate take this
in its constructor so that the base class doesn't need to have this parameter/getter/setter
which is specific to a specific implementation.

Line 1540: DdlDelegate ddlDelegate = createDdlDelegate(newTable)
         :         .setDistributeParams(distributeBy);
         :     ddlDelegate.createTable();
Marcel had said in the sync-up about doing this only when you had a real delegate (i.e. not
having a "no-op delegate")?

Line 1558: ddlDelegate.dropTable();
This would be affected as well
File testdata/workloads/functional-query/queries/QueryTest/kudu-show-create.test:

what about distribution parameters?
File tests/common/

Line 52: def get_db_name(cls):
       :     if not cls.__DB_NAME:
       :       cls.__DB_NAME = \
       :           choice(ascii_lowercase) + "".join(sample(ascii_lowercase + digits, 5))
       :     return cls.__DB_NAME
what about handling the race?

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Gerrit-MessageType: comment
Gerrit-Change-Id: Ic141102818b6dad3016181b179a14024d0ff709d
Gerrit-PatchSet: 7
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Casey Ching <>
Gerrit-Reviewer: Casey Ching <>
Gerrit-Reviewer: Matthew Jacobs <>
Gerrit-HasComments: Yes

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