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https://issues.apache.org/jira/browse/PHOENIX-1645?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14310822#comment-14310822
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Maryann Xue commented on PHOENIX-1645:
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That's my point, [~mujtabachohan]. The original optimal plan uses idx4, while
in the hint idx1 appears first.
1-CHUNK PARALLEL 1-WAY RANGE SCAN OVER IDX4 [*] - [10]
SERVER FILTER BY TO_LONG(DB) < 200
SERVER AGGREGATE INTO SINGLE ROW
I am not very sure, but I think it is either that Phoenix uses the first doable
hinted plan or that the comparison between the plan using idx1 and the plan
using idx4 does not show which is more expensive.
> Wrong execution plan generated for indexed query which leads to slow
> performance
> --------------------------------------------------------------------------------
>
> Key: PHOENIX-1645
> URL: https://issues.apache.org/jira/browse/PHOENIX-1645
> Project: Phoenix
> Issue Type: Bug
> Affects Versions: 4.3
> Reporter: Mujtaba Chohan
> Assignee: James Taylor
>
> Query: select /*+ INDEX(INDEXED_TABLE idx1 idx2 idx3 idx4) */ count(core)
> from INDEXED_TABLE where core < 10 and db < 200
> Optimal explain plan generated in Phoenix v4.2: 1-CHUNK PARALLEL 1-WAY RANGE
> SCAN OVER IDX4 [*] - [10]
> SERVER FILTER BY TO_LONG(DB) < 200
> SERVER AGGREGATE INTO SINGLE ROW
> *Wrong plan generated in 4.3 that uses skip scan join to base table.
> Performance of this plan compared to v4.2 is close to 20X slower with 2M rows
> data*: CLIENT 28-CHUNK PARALLEL 1-WAY FULL SCAN OVER INDEXED_TABLE
> SERVER FILTER BY USAGE.DB < 200
> SERVER AGGREGATE INTO SINGLE ROW
> SKIP-SCAN-JOIN TABLE 0
> CLIENT 1-CHUNK PARALLEL 1-WAY RANGE SCAN OVER IDX1 [*] - [10]
> SERVER FILTER BY FIRST KEY ONLY
> DYNAMIC SERVER FILTER BY ("HOST", "DOMAIN", "FEATURE", "DATE") IN
> (($22.$24, $22.$25, $22.$26, $22.$27))
>
> DDL: CREATE TABLE $TABLE (HOST CHAR(2) NOT NULL,DOMAIN VARCHAR NOT
> NULL,FEATURE VARCHAR NOT NULL,DATE DATE NOT NULL,USAGE.CORE BIGINT,USAGE.DB
> BIGINT,STATS.ACTIVE_VISITOR INTEGER CONSTRAINT PK PRIMARY KEY (HOST, DOMAIN,
> FEATURE, DATE)) IMMUTABLE_ROWS=true,MAX_FILESIZE=30485760;CREATE INDEX idx1
> ON $TABLE (CORE);CREATE INDEX idx2 ON $TABLE (DB);CREATE INDEX idx3 ON $TABLE
> (DB,ACTIVE_VISITOR);CREATE INDEX idx4 ON $TABLE
> (CORE,DB,ACTIVE_VISITOR);CREATE INDEX ids1 ON $TABLE (CORE)
> SALT_BUCKETS=16;CREATE INDEX ids2 ON $TABLE (DB) SALT_BUCKETS=16;CREATE INDEX
> ids3 ON $TABLE (DB,ACTIVE_VISITOR) SALT_BUCKETS=16;CREATE INDEX ids4 ON
> $TABLE (CORE,DB,ACTIVE_VISITOR) SALT_BUCKETS=16;
> Also see perf. run at:
> http://phoenix-bin.github.io/client/performance/phoenix-20150206042353.htm
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