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https://issues.apache.org/jira/browse/HIVE-23031?focusedWorklogId=429055&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-429055
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ASF GitHub Bot logged work on HIVE-23031:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 30/Apr/20 14:39
Start Date: 30/Apr/20 14:39
Worklog Time Spent: 10m
Work Description: kgyrtkirk commented on a change in pull request #988:
URL: https://github.com/apache/hive/pull/988#discussion_r418060431
##########
File path: common/src/java/org/apache/hadoop/hive/conf/HiveConf.java
##########
@@ -2465,6 +2465,19 @@ private static void
populateLlapDaemonVarsSet(Set<String> llapDaemonVarsSetLocal
"If the number of references to a CTE clause exceeds this threshold,
Hive will materialize it\n" +
"before executing the main query block. -1 will disable this
feature."),
+ HIVE_OPTIMIZE_BI_ENABLED("hive.optimize.bi.enabled", false,
+ "Enables query rewrites based on approximate functions(sketches)."),
+
+
HIVE_OPTIMIZE_BI_REWRITE_COUNTDISTINCT_ENABLED("hive.optimize.bi.rewrite.countdistinct.enabled",
+ true,
+ "Enables to rewrite COUNT(DISTINCT(X)) queries to be rewritten to use
sketch functions."),
+
+ HIVE_OPTIMIZE_BI_REWRITE_COUNT_DISTINCT_SKETCH(
+ "hive.optimize.bi.rewrite.countdistinct.sketch", "hll",
+ new StringSet("hll", "cpc", "theta"),
Review comment:
I don't think that would be neccessary
* it works correctly - even if we have 1 algo the interesting behaviour is
still there - which is: if the rewrite is enabled the created MV will be a
rewritten one
* it won't get applied for different modes/etc so it doesn't lead to errors
at all...
I've added a test(sketches_materialized_view_sketchtype.q)
which shows how it works when there is an MV for HLL ; in case the mode is
not HLL the MV is ignored and computed directly
I think the real meaning of the MV should not change(I think we agree on
this); we have 2 choices here:
* ignore all rewriting during MV construction/rebuild - so this rewrite may
not happen for an MV - and users have to use the expanded form of the sketch
stuff to create an MV for that purpose
* save a conf overlay alongside with the MV
I think addressing this is outside of the scope of this change
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Issue Time Tracking
-------------------
Worklog Id: (was: 429055)
Time Spent: 2h 50m (was: 2h 40m)
> Add option to enable transparent rewrite of count(distinct) into sketch
> functions
> ---------------------------------------------------------------------------------
>
> Key: HIVE-23031
> URL: https://issues.apache.org/jira/browse/HIVE-23031
> Project: Hive
> Issue Type: Sub-task
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
> Attachments: HIVE-23031.01.patch, HIVE-23031.02.patch,
> HIVE-23031.03.patch, HIVE-23031.03.patch, HIVE-23031.03.patch,
> HIVE-23031.04.patch, HIVE-23031.04.patch
>
> Time Spent: 2h 50m
> Remaining Estimate: 0h
>
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