[
https://issues.apache.org/jira/browse/HIVE-18079?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Gopal V updated HIVE-18079:
---------------------------
Attachment: HIVE-18079.5.patch
Rebase + explain one change to a test.
{code}
2018-01-02T20:25:52,726 DEBUG [36da1c38-207d-4b70-bb09-ff320a0062a3 main]
calcite.sql2rel: Plan after trimming unused fields
HiveProject(key=[$0], key1=[$3])
HiveJoin(condition=[=($1, $4)], joinType=[inner], algorithm=[none], cost=[not
available])
HiveJoin(condition=[=($0, $2)], joinType=[inner], algorithm=[none],
cost=[not available])
HiveFilter(condition=[AND(IS NOT NULL($0), IS NOT NULL($1))])
HiveProject(key=[$0], value=[$1])
HiveTableScan(table=[[default.tab_part]], table:alias=[a])
HiveFilter(condition=[IS NOT NULL($0)])
HiveProject(key=[$0])
HiveTableScan(table=[[default.tab_part]], table:alias=[c])
HiveFilter(condition=[IS NOT NULL($1)])
HiveProject(key=[$0], value=[$1])
HiveTableScan(table=[[default.tab_part]], table:alias=[b])
{code}
became
{code}
2018-01-02T20:25:52,925 DEBUG [36da1c38-207d-4b70-bb09-ff320a0062a3 main]
translator.PlanModifierForASTConv: Original plan for PlanModifier
HiveProject(key=[$0], key1=[$2])
HiveJoin(condition=[=($0, $4)], joinType=[inner], algorithm=[none], cost=[not
available])
HiveJoin(condition=[=($1, $3)], joinType=[inner], algorithm=[none],
cost=[not available])
HiveProject(key=[$0], value=[$1])
HiveFilter(condition=[AND(IS NOT NULL($0), IS NOT NULL($1))])
HiveTableScan(table=[[default.tab_part]], table:alias=[a])
HiveProject(key=[$0], value=[$1])
HiveFilter(condition=[IS NOT NULL($1)])
HiveTableScan(table=[[default.tab_part]], table:alias=[b])
HiveProject(key=[$0])
HiveFilter(condition=[IS NOT NULL($0)])
HiveTableScan(table=[[default.tab_part]], table:alias=[c]
{code}
> Statistics: Allow HyperLogLog to be merged to the lowest-common-denominator
> bit-size
> ------------------------------------------------------------------------------------
>
> Key: HIVE-18079
> URL: https://issues.apache.org/jira/browse/HIVE-18079
> Project: Hive
> Issue Type: Improvement
> Components: Standalone Metastore, Statistics
> Affects Versions: 3.0.0
> Reporter: Gopal V
> Assignee: Gopal V
> Attachments: HIVE-18079.1.patch, HIVE-18079.2.patch,
> HIVE-18079.4.patch, HIVE-18079.5.patch
>
>
> HyperLogLog can merge a 14 bit HLL into a 10 bit HLL bitset, because of its
> mathematical hash distribution & construction.
> Allow the squashing of a 14 bit HLL -> 10 bit HLL without needing a second
> scan over the data-set.
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