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[IMPALA-7608] Estimate row count from file size when no stats available - Impala - [issue]
...Impala makes heavy use of stats, which is a good thing. Stats feed into query planning where they allow the planner to choose among a fixed set of alternatives such as: do I put t1 on the bu...    Author: Paul Rogers , 2018-09-22, 02:04
[IMPALA-7601] Define a-priori selectivity and NDV values - Impala - [issue]
...Impala makes extensive use of table stats during query planning. For example, the NDV (number of distinct values) is used to compute selectivity, the degree of reduction (also called the red...    Author: Paul Rogers , 2018-09-21, 23:52
[IMPALA-7604] In AggregationNode.computeStats, handle cardinality overflow better - Impala - [issue]
...Consider the cardinality overflow logic in AggregationNode.computeStats(). Current code:    // if we ended up with an overflow, the estimate is certain to be wrong    if ...    Author: Paul Rogers , 2018-09-21, 04:32
[IMPALA-7603] Incorrect NDV expression for col1 op col2 - Impala - [issue]
...Consider the ExprNdvTest test case. The code contains tests for the CASE expression. Add tests for simple arithmetic expressions:    verifyNdv("id + 2", 7300);    verifyN...    Author: Paul Rogers , 2018-09-20, 22:05
[IMPALA-7602] Definition of NDV differs between planner and stats mechanism - Impala - [issue]
...See IMPALA-7310 which says that the Impala NDV function is implemented as "number of non-null distinct values." IMPALA-7310 also says that the stats gathering mechanism uses the same definit...    Author: Paul Rogers , 2018-09-20, 21:06
[expand - 1 more] - (Ab)using parquet files on S3 storage for a huge logging database - Arrow - [mail # dev]
...Hi Gerlando,Parquet does not allow row-level indexing because some data for a row might not even exist, it is encoded in data about a group of similar rows.In the world of Big Data, it seems...
   Author: Paul Rogers , 2018-09-19, 21:04
[expand - 2 more] - Confluence access - Impala - [mail # dev]
...Works fine. Thanks Phil!- Paul> On Sep 18, 2018, at 3:05 PM, Philip Zeyliger  wrote:> > I think I granted you access; try now!> > On Tue, Sep 18, 2018 at 3:04 PM Paul Rog...
   Author: Paul Rogers , 2018-09-18, 22:45
Contrib module not in root pom.xml? - Drill - [mail # dev]
...Hi All,I'm hoping someone can explain a mystery in the root pom.xml file. We have a list of modules:      tools    protocol    common    logical    exec    drill-yarn    distribution  Note t...
   Author: Paul Rogers , 2018-09-12, 01:21
[expand - 1 more] - Drill in the distributed compute jungle - Drill - [mail # dev]
...Hi Tim,You said it very well: think in terms of libraries, not services. This is exactly the right perspective.It is important to recognize that Drill, itself, was created by leveraging many...
   Author: Paul Rogers , 2018-09-11, 02:01
[expand - 1 more] - Possible way to specify column types in query - Drill - [mail # dev]
...Hi Weijie,Thanks for the paper pointer. F1 uses the same syntax as Scope (the system cited in my earlier note): data type after the name.Another description is [1]. Neither paper describe ho...
   Author: Paul Rogers , 2018-09-10, 04:42