[jira] Commented: (PIG-1637) Combiner not use because optimizor inserts a foreach between group and algebric function
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https://issues.apache.org/jira/browse/PIG-1637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12915880#action_12915880
]
Daniel Dai commented on PIG-1637:
-
test-patch result for PIG-1637-2.patch:
[exec] +1 overall.
[exec]
[exec] +1 @author. The patch does not contain any @author tags.
[exec]
[exec] +1 tests included. The patch appears to include 3 new or
modified tests.
[exec]
[exec] +1 javadoc. The javadoc tool did not generate any warning
messages.
[exec]
[exec] +1 javac. The applied patch does not increase the total number
of javac compiler warnings.
[exec]
[exec] +1 findbugs. The patch does not introduce any new Findbugs
warnings.
[exec]
[exec] +1 release audit. The applied patch does not increase the
total number of release audit warnings.
Combiner not use because optimizor inserts a foreach between group and
algebric function
Key: PIG-1637
URL: https://issues.apache.org/jira/browse/PIG-1637
Project: Pig
Issue Type: Bug
Affects Versions: 0.8.0
Reporter: Daniel Dai
Assignee: Daniel Dai
Fix For: 0.8.0
Attachments: PIG-1637-1.patch, PIG-1637-2.patch
The following script does not use combiner after new optimization change.
{code}
A = load ':INPATH:/pigmix/page_views' using
org.apache.pig.test.udf.storefunc.PigPerformanceLoader()
as (user, action, timespent, query_term, ip_addr, timestamp,
estimated_revenue, page_info, page_links);
B = foreach A generate user, (int)timespent as timespent,
(double)estimated_revenue as estimated_revenue;
C = group B all;
D = foreach C generate SUM(B.timespent), AVG(B.estimated_revenue);
store D into ':OUTPATH:';
{code}
This is because after group, optimizer detect group key is not used
afterward, it add a foreach statement after C. This is how it looks like
after optimization:
{code}
A = load ':INPATH:/pigmix/page_views' using
org.apache.pig.test.udf.storefunc.PigPerformanceLoader()
as (user, action, timespent, query_term, ip_addr, timestamp,
estimated_revenue, page_info, page_links);
B = foreach A generate user, (int)timespent as timespent,
(double)estimated_revenue as estimated_revenue;
C = group B all;
C1 = foreach C generate B;
D = foreach C1 generate SUM(B.timespent), AVG(B.estimated_revenue);
store D into ':OUTPATH:';
{code}
That cancel the combiner optimization for D.
The way to solve the issue is to merge the C1 we inserted and D. Currently,
we do not merge these two foreach. The reason is that one output of the first
foreach (B) is referred twice in D, and currently rule assume after merge, we
need to calculate B twice in D. Actually, C1 is only doing projection, no
calculation of B. Merging C1 and D will not result calculating B twice. So C1
and D should be merged.
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[jira] Commented: (PIG-1637) Combiner not use because optimizor inserts a foreach between group and algebric function
[
https://issues.apache.org/jira/browse/PIG-1637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12915950#action_12915950
]
Daniel Dai commented on PIG-1637:
-
Yes, it could be improved as per Xuefu's suggestion. Anyway, current patch
solve the combiner not used issue, will commit this part first. I will open
another Jira to improve it. Also, MergeForEach is a best example to practice
cloning framework [PIG-1587|https://issues.apache.org/jira/browse/PIG-1587], so
it is better to improve it once PIG-1587 is available.
Combiner not use because optimizor inserts a foreach between group and
algebric function
Key: PIG-1637
URL: https://issues.apache.org/jira/browse/PIG-1637
Project: Pig
Issue Type: Bug
Affects Versions: 0.8.0
Reporter: Daniel Dai
Assignee: Daniel Dai
Fix For: 0.8.0
Attachments: PIG-1637-1.patch, PIG-1637-2.patch
The following script does not use combiner after new optimization change.
{code}
A = load ':INPATH:/pigmix/page_views' using
org.apache.pig.test.udf.storefunc.PigPerformanceLoader()
as (user, action, timespent, query_term, ip_addr, timestamp,
estimated_revenue, page_info, page_links);
B = foreach A generate user, (int)timespent as timespent,
(double)estimated_revenue as estimated_revenue;
C = group B all;
D = foreach C generate SUM(B.timespent), AVG(B.estimated_revenue);
store D into ':OUTPATH:';
{code}
This is because after group, optimizer detect group key is not used
afterward, it add a foreach statement after C. This is how it looks like
after optimization:
{code}
A = load ':INPATH:/pigmix/page_views' using
org.apache.pig.test.udf.storefunc.PigPerformanceLoader()
as (user, action, timespent, query_term, ip_addr, timestamp,
estimated_revenue, page_info, page_links);
B = foreach A generate user, (int)timespent as timespent,
(double)estimated_revenue as estimated_revenue;
C = group B all;
C1 = foreach C generate B;
D = foreach C1 generate SUM(B.timespent), AVG(B.estimated_revenue);
store D into ':OUTPATH:';
{code}
That cancel the combiner optimization for D.
The way to solve the issue is to merge the C1 we inserted and D. Currently,
we do not merge these two foreach. The reason is that one output of the first
foreach (B) is referred twice in D, and currently rule assume after merge, we
need to calculate B twice in D. Actually, C1 is only doing projection, no
calculation of B. Merging C1 and D will not result calculating B twice. So C1
and D should be merged.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
