Paul Rogers has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/12438 )

Change subject: IMPALA-8181: Abbreviate row counts in EXPLAIN
......................................................................


Patch Set 5:

(2 comments)

Addressed comments. Found one more cardinality field to abbreviate. Because the 
EXPLAIN output changed again, need to rerun all the pre-review tests. Will post 
an update when that completes.

http://gerrit.cloudera.org:8080/#/c/12438/5/fe/src/main/java/org/apache/impala/common/PrintUtils.java
File fe/src/main/java/org/apache/impala/common/PrintUtils.java:

http://gerrit.cloudera.org:8080/#/c/12438/5/fe/src/main/java/org/apache/impala/common/PrintUtils.java@64
PS5, Line 64: if (value == -1) return "unavailable";
> Shouldn't we instead use printCardinality() or some other helper instead of
Done


http://gerrit.cloudera.org:8080/#/c/12438/5/fe/src/main/java/org/apache/impala/common/PrintUtils.java@66
PS5, Line 66:     if (value >= TERA) return new 
DecimalFormat(".00T").format(result / TERA);
> Curious if we should be consistent with the backend metrics which print wit
Created an "exact cardinality" method to format the values as suggested. Then, 
I went in search of which methods should use the "estimated" cardinality format 
vs. the "exact" cardinality format. I found that, in the planner, all 
cardinalities are estimates.

This rounding shows at least three digits of precision, so if a number is, say, 
1, 12 or 123, we'll see the exact number. But, if the number is large, we'll 
see an abbreviation, which is about as accurate as the underlying estimate (and 
easier to read.)

Can add the extra field later if we discover a place where we have exactly 
accurate values.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I08faaa9ad7b5ed42dcd7a15a333e8734bb45f10c
Gerrit-Change-Number: 12438
Gerrit-PatchSet: 5
Gerrit-Owner: Paul Rogers <[email protected]>
Gerrit-Reviewer: Bharath Vissapragada <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Paul Rogers <[email protected]>
Gerrit-Comment-Date: Wed, 20 Feb 2019 00:28:43 +0000
Gerrit-HasComments: Yes

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