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Posted to reviews@kudu.apache.org by "wangning (Code Review)" <ge...@cloudera.org> on 2020/10/29 06:42:04 UTC

[kudu-CR] KUDU-1644 hash-partition based partition optimization

wangning has uploaded this change for review. ( http://gerrit.cloudera.org:8080/16674


Change subject: KUDU-1644 hash-partition based partition optimization
......................................................................

KUDU-1644 hash-partition based partition optimization

Hash prune for single hash-key based inList query. Reduce the prediated
values by hash-partition calculation.

Table has P partitions, N records, R rowsets. Inlist predicate has V
values.

Before:
Complexity to complete hash-key based in-list query is:
V * LOG(N/R) * N

After:
Complexity becomes:
V/P * LOG(N/R) * N

E.g.
Hash partition of table profile:
hash(id) profile by id partitions 3, simply use mod as hash function.
select * from list where id in (1,2,3,4,5,6,7,8,9,10)

Before:
Tablet 1: id in (1,2,3,4,5,6,7,8,9,10)
Tablet 2: id in (1,2,3,4,5,6,7,8,9,10)
Tablet 3: id in (1,2,3,4,5,6,7,8,9,10)

After:
Tablet 1: id in (0, 3, 6, 9)
Tablet 2: id in (1, 4, 7, 10)
Tablet 3: id in (2, 5, 8)

Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
---
M src/kudu/common/column_predicate.h
M src/kudu/common/partial_row.h
M src/kudu/common/partition.h
M src/kudu/common/scan_spec.cc
M src/kudu/common/scan_spec.h
M src/kudu/tserver/tablet_service.cc
6 files changed, 72 insertions(+), 2 deletions(-)



  git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/74/16674/1
-- 
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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
Gerrit-Change-Number: 16674
Gerrit-PatchSet: 1
Gerrit-Owner: wangning <19...@gmail.com>

[kudu-CR] KUDU-1644 hash-partition based partition optimization

Posted by "wangning (Code Review)" <ge...@cloudera.org>.

Hello Tidy Bot, Kudu Jenkins, Andrew Wong, 

I'd like you to reexamine a change. Please visit

    http://gerrit.cloudera.org:8080/16674

to look at the new patch set (#6).

Change subject: KUDU-1644 hash-partition based partition optimization
......................................................................

KUDU-1644 hash-partition based partition optimization

Hash prune for single hash-key based inList query. Reduce the values to predicate
by hash-partition match.

Table has P partitions, N records, R rowsets. Inlist predicate has V
values.

Before:
To each tablet, time complexity to complete hash-key based in-list query is:
V * LOG(N/R) * N

After:
Complexity becomes:
V/P * LOG(N/R) * N

E.g.
Hash partition of table profile:
hash(id) profile by id partitions 3, simply use mod as hash function.
select * from list where id in (1,2,3,4,5,6,7,8,9,10)

Before:
Tablet 1: id in (1,2,3,4,5,6,7,8,9,10)
Tablet 2: id in (1,2,3,4,5,6,7,8,9,10)
Tablet 3: id in (1,2,3,4,5,6,7,8,9,10)

After:
Tablet 1: id in (0, 3, 6, 9)
Tablet 2: id in (1, 4, 7, 10)
Tablet 3: id in (2, 5, 8)

Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
---
M src/kudu/common/column_predicate.h
M src/kudu/common/partial_row.cc
M src/kudu/common/partial_row.h
M src/kudu/common/partition.h
M src/kudu/common/partition_pruner-test.cc
M src/kudu/common/scan_spec-test.cc
M src/kudu/common/scan_spec.cc
M src/kudu/common/scan_spec.h
M src/kudu/tserver/tablet_service.cc
9 files changed, 339 insertions(+), 9 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/74/16674/6
-- 
To view, visit http://gerrit.cloudera.org:8080/16674
To unsubscribe, visit http://gerrit.cloudera.org:8080/settings

Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
Gerrit-Change-Number: 16674
Gerrit-PatchSet: 6
Gerrit-Owner: wangning <19...@gmail.com>
Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Tidy Bot (241)

[kudu-CR] KUDU-1644 hash-partition based in-list predicate optimization

Posted by "wangning (Code Review)" <ge...@cloudera.org>.

Hello Mahesh Reddy, Tidy Bot, Kudu Jenkins, Andrew Wong, Bankim Bhavsar, 

I'd like you to reexamine a change. Please visit

    http://gerrit.cloudera.org:8080/16674

to look at the new patch set (#15).

Change subject: KUDU-1644 hash-partition based in-list predicate optimization
......................................................................

KUDU-1644 hash-partition based in-list predicate optimization

Hash prune for single hash-key based inList query. Reduce the values to predicate
by hash-partition match.
This patch reduces the IN List predicated values to be pushed to tablet
without change the content to be returned.

Table has P partitions, N records, R rowsets. Inlist predicate has V values.

Before:
To each tablet, time complexity to complete hash-key based in-list query is:
V * LOG(N/R) * N

After:
Complexity becomes:
V/P * LOG(N/R) * N

E.g.
Hash partition of table 'profile':
hash(id) by id partitions 3, simply use mod as hash function.
select * from profile where id in (1,2,3,4,5,6,7,8,9,10)

Before:
Tablet 1: id in (1,2,3,4,5,6,7,8,9,10)
Tablet 2: id in (1,2,3,4,5,6,7,8,9,10)
Tablet 3: id in (1,2,3,4,5,6,7,8,9,10)

After:
Tablet 1: id in (0,3,6,9)
Tablet 2: id in (1,4,7,10)
Tablet 3: id in (2,5,8)

Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
---
M java/kudu-client/src/test/java/org/apache/kudu/client/TestAlterTable.java
M src/kudu/common/column_predicate.h
M src/kudu/common/partial_row.cc
M src/kudu/common/partial_row.h
M src/kudu/common/partition.cc
M src/kudu/common/partition.h
M src/kudu/common/partition_pruner-test.cc
M src/kudu/common/scan_spec-test.cc
M src/kudu/common/scan_spec.cc
M src/kudu/common/scan_spec.h
M src/kudu/tserver/tablet_service.cc
11 files changed, 560 insertions(+), 22 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/74/16674/15
-- 
To view, visit http://gerrit.cloudera.org:8080/16674
To unsubscribe, visit http://gerrit.cloudera.org:8080/settings

Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
Gerrit-Change-Number: 16674
Gerrit-PatchSet: 15
Gerrit-Owner: wangning <19...@gmail.com>
Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Bankim Bhavsar <ba...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Mahesh Reddy <mr...@cloudera.com>
Gerrit-Reviewer: Tidy Bot (241)
Gerrit-Reviewer: wangning <19...@gmail.com>

[kudu-CR] KUDU-1644 hash-partition based in-list predicate optimization

Posted by "wangning (Code Review)" <ge...@cloudera.org>.

wangning has posted comments on this change. ( http://gerrit.cloudera.org:8080/16674 )

Change subject: KUDU-1644 hash-partition based in-list predicate optimization
......................................................................


Patch Set 14:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/tserver/tablet_service.cc
File src/kudu/tserver/tablet_service.cc:

http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/tserver/tablet_service.cc@2667
PS8, Line 2667: 
              :   spec.OptimizeScan(tablet_schema, scanner->arena(), true);
              :   VLOG(3) << "After
> If we pushed the emptiness check into CanShortCircuit(), would that avoid t
That seems bit different, it seems not good to detect can shortcircuit here. It will return wrong answer and result in the failure of TabletServerTest.TestNonPositiveLimitsShortCircuit
/
I will split them and re-patch



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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
Gerrit-Change-Number: 16674
Gerrit-PatchSet: 14
Gerrit-Owner: wangning <19...@gmail.com>
Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Bankim Bhavsar <ba...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Mahesh Reddy <mr...@cloudera.com>
Gerrit-Reviewer: Tidy Bot (241)
Gerrit-Reviewer: wangning <19...@gmail.com>
Gerrit-Comment-Date: Tue, 03 Nov 2020 10:24:25 +0000
Gerrit-HasComments: Yes

[kudu-CR] KUDU-1644 hash-partition based in-list predicate optimization

Posted by "Andrew Wong (Code Review)" <ge...@cloudera.org>.

Andrew Wong has posted comments on this change. ( http://gerrit.cloudera.org:8080/16674 )

Change subject: KUDU-1644 hash-partition based in-list predicate optimization
......................................................................


Patch Set 8:

(14 comments)

http://gerrit.cloudera.org:8080/#/c/16674/7//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/16674/7//COMMIT_MSG@2
PS7, Line 2:   ningw <19...@gmail.com>
           : AuthorDate: 
> this patch is target on 
nit: could you add a TODO comment in PruneHashForInlistIfPossible mentioning this? I agree this would be a good improvement to make, and it'd be nice to have a pointer in the code both explaining the limitations of the code today, and ideas for improvement.


http://gerrit.cloudera.org:8080/#/c/16674/8//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/16674/8//COMMIT_MSG@31
PS8, Line 31: 
            : After:
            : Tablet 1: id in (0,3,6,9)
            : Tablet 2: id in (1,4,7,10)
            : Tablet 3: id in (2,5,8)
Making sure my understanding is correct here -- this doesn't reduce the number of rows sent back by the servers, but:
- it does reduce the CPU used when evaluating the in-list predicates since the predicates themselves are smaller
- it also allows us to short-circuit immediately if the in-list predicate only contains values that are not in a given tablet


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec-test.cc
File src/kudu/common/scan_spec-test.cc:

http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec-test.cc@473
PS8, Line 473: ASSERT_EQ(spec_p1.IsInListPredicateValuesEmpty(), false);
nit: you can use ASSERT_TRUE and ASSERT_FALSE for these


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec-test.cc@503
PS8, Line 503: columnPB
nit: We use snake_case for variable names in our C++ code. Same elsewhere


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec-test.cc@518
PS8, Line 518: parition
nit: "partition", same elsewhere


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec-test.cc@553
PS8, Line 553: / Test that hash(a, b), hash(c) InList predicates.
             : // Neither a or b InList can be pruned.
             : // c InList should be pruned.
Could you also add a case for hash(a), hash(b)?


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec-test.cc@563
PS8, Line 563: 
             :   PartitionSchema partition_schema;
             :   PartitionSchemaPB partition_schemaPB;
             :   auto* hashPB = partition_schemaPB.add_hash_bucket_schemas();
             :   hashPB->set_num_buckets(3);
             :   hashPB->set_seed(0);
             :   auto* columnPB_1_1 = hashPB->add_columns();
             :   int key_column_id_1_1 = schema.find_column("a");
             :   columnPB_1_1->set_id(key_column_id_1_1);
             :   columnPB_1_1->set_name("a");
             : 
             :   auto* columnPB_1_2 = hashPB->add_columns();
             :   int key_column_id_1_2 = schema.find_column("b");
             :   columnPB_1_2->set_id(key_column_id_1_2);
             :   columnPB_1_2->set_name("b");
             : 
             :   auto* hashPB_2_1 = partition_schemaPB.add_hash_bucket_schemas();
             :   hashPB_2_1->set_num_buckets(3);
             :   hashPB_2_1->set_seed(0);
             :   auto* columnPB_2_1 = hashPB_2_1->add_columns();
             :   int key_column_id_2_1 = schema.find_column("c");
             :   columnPB_2_1->set_id(key_column_id_2_1);
             :   columnPB_2_1->set_name("c");
             : 
             :   ASSERT_OK(PartitionSchema::FromPB(partition_schemaPB, schema, &partition_schema));
nit: seems like this code is reused a bunch in these tests. Maybe define a function in an anonymous namespace like:

namespace {

PartitionSchema GeneratePartitionSchema(const vector<pair<vector<string>, int>> hash_partitions, ...) {
  PartitionsSchemaPB partition_schema_pb;
  for (const auto& col_names_and_num_buckets : hash_partitions) {
    auto* hash_pb = partition_schema_pb.add_hash_bucket_schemas();
    hash_pb->set_num_buckets(col_names_and_num_buckets.second);
    for (const auto& col_name : col_names_and_num_buckets.first) {
      hash_pb->(set fields...)
    }
  }
  PartitionSchema partition_schema;
  CHECK_OK(FromPB(partition_schema_pb, &partition_schema));
  return partition_schema;
}

} // anonymous namespace

That way, these tests can just call

 const auto partition_schema = GeneratePartitionSchema({ make_pair({ "a", "b" }, 3), make_pair({ "c" }, 1) });


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec.cc
File src/kudu/common/scan_spec.cc:

http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec.cc@88
PS8, Line 88:                   return predicate.second.predicate_type() == PredicateType::None;
Why shouldn't we put the InList empty check here?


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec.cc@191
PS8, Line 191:     if (predicate.predicate_type() == PredicateType::InList) {
We should be able to push this to the front of the loop and avoid a FindColumn() call, e.g.

for (auto& p : predicates_) {
  if (predicate.predicate_type() != PredicateType::InList) continue;
  ...
}


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec.cc@193
PS8, Line 193: col_name,
nit: we've already found the column index -- could we pass 'idx' or the column ID here and avoid an extra FindColumn()?


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec.cc@193
PS8, Line 193: IsSingleColumnHashParition
nit: typo in "Partition"


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec.cc@205
PS8, Line 205: Status s = Status::OK();
             :           s = partial_row.Set(idx, reinterpret_cast<const uint8_t*>(value));
nit: can merge these lines


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/tserver/tablet_service.cc
File src/kudu/tserver/tablet_service.cc:

http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/tserver/tablet_service.cc@2667
PS8, Line 2667: // However, it may crash in coming 'OptimizeScan' call to use empty
              :     // predicate value, here could protects special case with minor cost during
              :     // setup stage.
If we pushed the emptiness check into CanShortCircuit(), would that avoid the crash?


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/tserver/tablet_service.cc@2737
PS8, Line 2737:   if (spec.CanShortCircuit()) {
              :     VLOG(1) << "short-circuiting without creating a server-side scanner.";
              :     *has_more_results = false;
              :     return Status::OK();
              :   }
Hmm, I'm not sure, but could we move this up to right after OptimizeScan()? Seems like otherwise we are doing some work even though we are not going to return anything. Or do we need to short circuit _after_ validating the scan spec?



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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
Gerrit-Change-Number: 16674
Gerrit-PatchSet: 8
Gerrit-Owner: wangning <19...@gmail.com>
Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Mahesh Reddy <mr...@cloudera.com>
Gerrit-Reviewer: Tidy Bot (241)
Gerrit-Reviewer: wangning <19...@gmail.com>
Gerrit-Comment-Date: Fri, 30 Oct 2020 19:55:14 +0000
Gerrit-HasComments: Yes

[kudu-CR] KUDU-1644 hash-partition based in-list predicate optimization

Posted by "wangning (Code Review)" <ge...@cloudera.org>.

wangning has posted comments on this change. ( http://gerrit.cloudera.org:8080/16674 )

Change subject: KUDU-1644 hash-partition based in-list predicate optimization
......................................................................


Patch Set 17:

So sorry for patching so much that the msg is so messy for reviewing. I was busy tackling the break things detected by tidy and something else. The correctness and performance were tested in my environment with hours testing. 
Would you mind me abandon it and re-commit for review convenient?


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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
Gerrit-Change-Number: 16674
Gerrit-PatchSet: 17
Gerrit-Owner: wangning <19...@gmail.com>
Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Bankim Bhavsar <ba...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Mahesh Reddy <mr...@cloudera.com>
Gerrit-Reviewer: Tidy Bot (241)
Gerrit-Reviewer: wangning <19...@gmail.com>
Gerrit-Comment-Date: Thu, 05 Nov 2020 08:26:51 +0000
Gerrit-HasComments: No

[kudu-CR] KUDU-1644 hash-partition based in-list predicate optimization

Posted by "Andrew Wong (Code Review)" <ge...@cloudera.org>.

Andrew Wong has submitted this change and it was merged. ( http://gerrit.cloudera.org:8080/16674 )

Change subject: KUDU-1644 hash-partition based in-list predicate optimization
......................................................................

KUDU-1644 hash-partition based in-list predicate optimization

Hash prune for single hash-key based inList query. Reduce the values to predicate
by hash-partition match.
This patch reduces the IN List predicated values to be pushed to tablet
without change the content to be returned.

Table has P partitions, N records. Inlist predicate has V values.

Before:
To each tablet, time complexity to complete hash-key based in-list query is:
LOG(V) * N

After:
Complexity becomes:
LOG(V/P) * N

E.g.
Hash partition of table 'profile':
hash(id) by id partitions 3, simply use mod as hash function.
select * from profile where id in (1,2,3,4,5,6,7,8,9,10)

Before:
Tablet 1: id in (1,2,3,4,5,6,7,8,9,10)
Tablet 2: id in (1,2,3,4,5,6,7,8,9,10)
Tablet 3: id in (1,2,3,4,5,6,7,8,9,10)

After:
Tablet 1: id in (0,3,6,9)
Tablet 2: id in (1,4,7,10)
Tablet 3: id in (2,5,8)

Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
Reviewed-on: http://gerrit.cloudera.org:8080/16674
Tested-by: Kudu Jenkins
Reviewed-by: Andrew Wong <aw...@cloudera.com>
---
M java/kudu-client/src/test/java/org/apache/kudu/client/TestAlterTable.java
M src/kudu/common/column_predicate.h
M src/kudu/common/partial_row.cc
M src/kudu/common/partial_row.h
M src/kudu/common/partition.cc
M src/kudu/common/partition.h
M src/kudu/common/partition_pruner-test.cc
M src/kudu/common/scan_spec-test.cc
M src/kudu/common/scan_spec.cc
M src/kudu/common/scan_spec.h
M src/kudu/tserver/tablet_service.cc
11 files changed, 552 insertions(+), 26 deletions(-)

Approvals:
  Kudu Jenkins: Verified
  Andrew Wong: Looks good to me, approved

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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: merged
Gerrit-Change-Id: I202001535669a72de7fbb9e766dbc27db48e0aa2
Gerrit-Change-Number: 16674
Gerrit-PatchSet: 20
Gerrit-Owner: wangning <19...@gmail.com>
Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Bankim Bhavsar <ba...@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Mahesh Reddy <mr...@cloudera.com>
Gerrit-Reviewer: Tidy Bot (241)
Gerrit-Reviewer: wangning <19...@gmail.com>

[kudu-CR] KUDU-1644 hash-partition based in-list predicate optimization

Posted by "Bankim Bhavsar (Code Review)" <ge...@cloudera.org>.

Bankim Bhavsar has posted comments on this change. ( http://gerrit.cloudera.org:8080/16674 )

Change subject: KUDU-1644 hash-partition based in-list predicate optimization
......................................................................


Patch Set 8:

(5 comments)

http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/partial_row.h
File src/kudu/common/partial_row.h:

http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/partial_row.h@642
PS8, Line 642: // Runtime version of the generic setter.
Sorry I don't understand this comment. Also could you write it as per doxygen format?


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/partition.h
File src/kudu/common/partition.h:

http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/partition.h@267
PS8, Line 267: Parition
Typo


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/partition.h@266
PS8, Line 266: // Set is_hash_partition to true if col_name is one of hash partition schema.
             :   void IsSingleColumnHashParition(const Schema& schema,
             :                                   const std::string& col_name,
             :                                   bool* is_hash_partition) const {
It'd be better to return bool instead of using as an out parameter.


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec.h
File src/kudu/common/scan_spec.h:

http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec.h@62
PS8, Line 62:  empty.
is empty


http://gerrit.cloudera.org:8080/#/c/16674/8/src/kudu/common/scan_spec.h@80
PS8, Line 80: Support hash(onekey).
I suppose the comment indicates, "supports hash schema with only one key"?



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