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Posted to reviews@impala.apache.org by "anujphadke (Code Review)" <ge...@cloudera.org> on 2017/01/26 08:34:35 UTC
[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
anujphadke has uploaded a new change for review.
http://gerrit.cloudera.org:8080/5800
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
IMPALA-4738: STDDEV_SAMP should return NULL for single record input
In calculating the STDDEV_SAMP of N rows a divion by N-1 rows is involved.
Hence STDDEV_SAMP for a single row involves a division by 0. This change
returns a NULL instead of a 0 when calculating STDDEV_SAMP for a single row.
STDDEV_POP for single row will still return a 0 since this does not
involve a division by 0.
Change-Id: Ide8af752cd8a2e554a2cd5a1ec948967a80de1fe
---
M be/src/exprs/aggregate-functions-ir.cc
M testdata/workloads/functional-query/queries/QueryTest/aggregation.test
2 files changed, 4 insertions(+), 4 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/00/5800/1
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Gerrit-Change-Id: Ide8af752cd8a2e554a2cd5a1ec948967a80de1fe
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "anujphadke (Code Review)" <ge...@cloudera.org>.
anujphadke has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 2:
(1 comment)
http://gerrit.cloudera.org:8080/#/c/5800/1/testdata/workloads/functional-query/queries/QueryTest/aggregation.test
File testdata/workloads/functional-query/queries/QueryTest/aggregation.test:
PS1, Line 26: SELECT variance(tinyint_col), stddev(smallint_col),stddev_samp(smallint_col),
: variance_pop(int_col),
> please add a col for stddev_samp as well. even though they're aliased now,
Done
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "Matthew Jacobs (Code Review)" <ge...@cloudera.org>.
Matthew Jacobs has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 3: Code-Review+2
(2 comments)
Thanks! Please let John know that the existing doc needs to be updated.
http://gerrit.cloudera.org:8080/#/c/5800/3//COMMIT_MSG
Commit Message:
PS3, Line 9: In calculating the STDDEV_SAMP/VARIANCE of N rows a divion by N-1 rows is involved.
: Hence STDDEV_SAMP/VARIANCE for a single row involves a division by 0. This change
: returns a NULL instead of a 0 when calculating STDDEV_SAMP/VARIANCE for a single row.
: STDDEV_POP/VARIANCE_POP for single row will still return a 0 since this does not involve a division
: by 0.
nit wrap at 80 chars
Line 14:
please mention this matches postgres behavior
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "Matthew Jacobs (Code Review)" <ge...@cloudera.org>.
Matthew Jacobs has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 1:
(2 comments)
http://gerrit.cloudera.org:8080/#/c/5800/1/be/src/exprs/aggregate-functions-ir.cc
File be/src/exprs/aggregate-functions-ir.cc:
PS1, Line 1348: DoubleVal AggregateFunctions::KnuthStddevFinalize(FunctionContext* ctx,
: const StringVal& state_sv) {
: DCHECK(!state_sv.is_null);
: DCHECK_EQ(state_sv.len, sizeof(KnuthVarianceState));
: KnuthVarianceState* state = reinterpret_cast<KnuthVarianceState*>(state_sv.ptr);
: if (state->count == 0 || state->count == 1) return DoubleVal::null();
: re
> STDDEV is an alias for STDDEV_SAMP according the impala documentation. Shou
If that's the case, though it is concerning Oracle's behavior differs. I see postgres does just alias them, so I guess that's fine as long as we're clear in the docs. Thanks for checking that.
http://gerrit.cloudera.org:8080/#/c/5800/1/testdata/workloads/functional-query/queries/QueryTest/aggregation.test
File testdata/workloads/functional-query/queries/QueryTest/aggregation.test:
PS1, Line 26: SELECT variance(tinyint_col), stddev(smallint_col), variance_pop(int_col),
: stddev_pop(bigint_col)
please add a col for stddev_samp as well. even though they're aliased now, let's make sure we cover both fns anyway for the future.
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "anujphadke (Code Review)" <ge...@cloudera.org>.
anujphadke has uploaded a new patch set (#2).
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
IMPALA-4738: STDDEV_SAMP should return NULL for single record input
In calculating the STDDEV_SAMP of N rows a divion by N-1 rows is involved.
Hence STDDEV_SAMP for a single row involves a division by 0. This change
returns a NULL instead of a 0 when calculating STDDEV_SAMP for a single row.
STDDEV_POP for single row will still return a 0 since this does not
involve a division by 0.
Change-Id: Ide8af752cd8a2e554a2cd5a1ec948967a80de1fe
---
M be/src/exprs/aggregate-functions-ir.cc
M testdata/workloads/functional-query/queries/QueryTest/aggregation.test
2 files changed, 7 insertions(+), 7 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/00/5800/2
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Gerrit-Change-Id: Ide8af752cd8a2e554a2cd5a1ec948967a80de1fe
Gerrit-PatchSet: 2
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Gerrit-Owner: anujphadke <ap...@cloudera.com>
Gerrit-Reviewer: Matthew Jacobs <mj...@cloudera.com>
Gerrit-Reviewer: anujphadke <ap...@cloudera.com>
[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "Matthew Jacobs (Code Review)" <ge...@cloudera.org>.
Matthew Jacobs has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 1:
(1 comment)
I think you need a new finalize function to separate stddev and stddev_samp
http://gerrit.cloudera.org:8080/#/c/5800/1/be/src/exprs/aggregate-functions-ir.cc
File be/src/exprs/aggregate-functions-ir.cc:
PS1, Line 1348: DoubleVal AggregateFunctions::KnuthStddevFinalize(FunctionContext* ctx,
: const StringVal& state_sv) {
: DCHECK(!state_sv.is_null);
: DCHECK_EQ(state_sv.len, sizeof(KnuthVarianceState));
: KnuthVarianceState* state = reinterpret_cast<KnuthVarianceState*>(state_sv.ptr);
: if (state->count == 0 || state->count == 1) return DoubleVal::null();
: re
this gets used by both stddev and stddev_samp, but it looks like Oracle (not sure about other DBs) do not return null for stddev when there is 1 row:
https://docs.oracle.com/cd/B19306_01/server.102/b14200/functions159.htm
... It differs from STDDEV_SAMP in that STDDEV returns zero when it has only 1 row of input data, whereas STDDEV_SAMP returns null. ...
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "anujphadke (Code Review)" <ge...@cloudera.org>.
anujphadke has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 4:
(2 comments)
http://gerrit.cloudera.org:8080/#/c/5800/3//COMMIT_MSG
Commit Message:
PS3, Line 9: In calculating the STDDEV_SAMP/VARIANCE of N rows a divion by
: N-1 rows is involved. Hence STDDEV_SAMP/VARIANCE for a single
: row involves a division by 0. This change returns a NULL instead
: of a 0 when calculating STDDEV_SAMP/VARIANCE for a single row.
: STDDE
> nit wrap at 80 chars
Done
Line 14: this does not involve a division by 0. This matches the postgres
> please mention this matches postgres behavior
Done
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "Impala Public Jenkins (Code Review)" <ge...@cloudera.org>.
Impala Public Jenkins has submitted this change and it was merged.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
IMPALA-4738: STDDEV_SAMP should return NULL for single record input
In calculating the STDDEV_SAMP/VARIANCE of N rows a divion by
N-1 rows is involved. Hence STDDEV_SAMP/VARIANCE for a single
row involves a division by 0. This change returns a NULL instead
of a 0 when calculating STDDEV_SAMP/VARIANCE for a single row.
STDDEV_POP/VARIANCE_POP for single row will still return a 0 since
this does not involve a division by 0. This matches the postgres
behavior.
Change-Id: Ide8af752cd8a2e554a2cd5a1ec948967a80de1fe
Reviewed-on: http://gerrit.cloudera.org:8080/5800
Reviewed-by: Matthew Jacobs <mj...@cloudera.com>
Tested-by: Impala Public Jenkins
---
M be/src/exprs/aggregate-functions-ir.cc
M testdata/workloads/functional-query/queries/QueryTest/aggregation.test
2 files changed, 8 insertions(+), 7 deletions(-)
Approvals:
Impala Public Jenkins: Verified
Matthew Jacobs: Looks good to me, approved
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Gerrit-Reviewer: Matthew Jacobs <mj...@cloudera.com>
Gerrit-Reviewer: anujphadke <ap...@cloudera.com>
[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "Matthew Jacobs (Code Review)" <ge...@cloudera.org>.
Matthew Jacobs has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 2: Code-Review+2
(2 comments)
please let john know we should doc this change
http://gerrit.cloudera.org:8080/#/c/5800/2/testdata/workloads/functional-query/queries/QueryTest/aggregation.test
File testdata/workloads/functional-query/queries/QueryTest/aggregation.test:
PS2, Line 26: ,
please add a space
PS2, Line 30: 0,0
so all of these match postgres now?
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "anujphadke (Code Review)" <ge...@cloudera.org>.
Hello Matthew Jacobs,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/5800
to look at the new patch set (#4).
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
IMPALA-4738: STDDEV_SAMP should return NULL for single record input
In calculating the STDDEV_SAMP/VARIANCE of N rows a divion by
N-1 rows is involved. Hence STDDEV_SAMP/VARIANCE for a single
row involves a division by 0. This change returns a NULL instead
of a 0 when calculating STDDEV_SAMP/VARIANCE for a single row.
STDDEV_POP/VARIANCE_POP for single row will still return a 0 since
this does not involve a division by 0. This matches the postgres
behavior.
Change-Id: Ide8af752cd8a2e554a2cd5a1ec948967a80de1fe
---
M be/src/exprs/aggregate-functions-ir.cc
M testdata/workloads/functional-query/queries/QueryTest/aggregation.test
2 files changed, 8 insertions(+), 7 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/00/5800/4
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Gerrit-Reviewer: anujphadke <ap...@cloudera.com>
[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "Matthew Jacobs (Code Review)" <ge...@cloudera.org>.
Matthew Jacobs has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 4: Code-Review+2
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "anujphadke (Code Review)" <ge...@cloudera.org>.
anujphadke has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 3:
(2 comments)
http://gerrit.cloudera.org:8080/#/c/5800/2/testdata/workloads/functional-query/queries/QueryTest/aggregation.test
File testdata/workloads/functional-query/queries/QueryTest/aggregation.test:
PS2, Line 26:
> please add a space
Done
PS2, Line 30:
> so all of these match postgres now?
variance function needed similar changes like std_dev.
Here is the output from postgres.
Last login: Thu Feb 2 12:32:04 on ttys000
"/Applications/Postgres.app/Contents/Versions/9.6/bin/psql" -p5432 -d "aphadke"
aphadke-MBP-2:~ aphadke$ "/Applications/Postgres.app/Contents/Versions/9.6/bin/psql" -p5432 -d "aphadke"
psql (9.6.1)
Type "help" for help.
aphadke=# select stddev_samp(56);
stddev_samp
-------------
(1 row)
aphadke=# select stddev(56);
stddev
--------
(1 row)
aphadke=# select stddev_pop(56);
stddev_pop
------------
0
(1 row)
aphadke=# select var_pop(56);
var_pop
---------
0
(1 row)
aphadke=# select var_samp(56);
var_samp
----------
(1 row)
aphadke=# select variance(56);
variance
----------
(1 row)
aphadke=#
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "anujphadke (Code Review)" <ge...@cloudera.org>.
anujphadke has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 1:
(1 comment)
http://gerrit.cloudera.org:8080/#/c/5800/1/be/src/exprs/aggregate-functions-ir.cc
File be/src/exprs/aggregate-functions-ir.cc:
PS1, Line 1348: DoubleVal AggregateFunctions::KnuthStddevFinalize(FunctionContext* ctx,
: const StringVal& state_sv) {
: DCHECK(!state_sv.is_null);
: DCHECK_EQ(state_sv.len, sizeof(KnuthVarianceState));
: KnuthVarianceState* state = reinterpret_cast<KnuthVarianceState*>(state_sv.ptr);
: if (state->count == 0 || state->count == 1) return DoubleVal::null();
: re
> this gets used by both stddev and stddev_samp, but it looks like Oracle (no
STDDEV is an alias for STDDEV_SAMP according the impala documentation. Shouldn't they behave the same in this case?
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "Impala Public Jenkins (Code Review)" <ge...@cloudera.org>.
Impala Public Jenkins has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 4: Verified+1
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "Impala Public Jenkins (Code Review)" <ge...@cloudera.org>.
Impala Public Jenkins has posted comments on this change.
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
Patch Set 4:
Build started: http://jenkins.impala.io:8080/job/gerrit-verify-dryrun/242/
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[Impala-ASF-CR] IMPALA-4738: STDDEV SAMP should return NULL for single record input
Posted by "anujphadke (Code Review)" <ge...@cloudera.org>.
Hello Matthew Jacobs,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/5800
to look at the new patch set (#3).
Change subject: IMPALA-4738: STDDEV_SAMP should return NULL for single record input
......................................................................
IMPALA-4738: STDDEV_SAMP should return NULL for single record input
In calculating the STDDEV_SAMP/VARIANCE of N rows a divion by N-1 rows is involved.
Hence STDDEV_SAMP/VARIANCE for a single row involves a division by 0. This change
returns a NULL instead of a 0 when calculating STDDEV_SAMP/VARIANCE for a single row.
STDDEV_POP/VARIANCE_POP for single row will still return a 0 since this does not involve a division
by 0.
Change-Id: Ide8af752cd8a2e554a2cd5a1ec948967a80de1fe
---
M be/src/exprs/aggregate-functions-ir.cc
M testdata/workloads/functional-query/queries/QueryTest/aggregation.test
2 files changed, 9 insertions(+), 8 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/00/5800/3
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Gerrit-Change-Id: Ide8af752cd8a2e554a2cd5a1ec948967a80de1fe
Gerrit-PatchSet: 3
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: anujphadke <ap...@cloudera.com>
Gerrit-Reviewer: Matthew Jacobs <mj...@cloudera.com>
Gerrit-Reviewer: anujphadke <ap...@cloudera.com>