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Posted to dev@phoenix.apache.org by "Istvan Toth (Jira)" <ji...@apache.org> on 2023/05/18 14:59:00 UTC
[jira] [Updated] (PHOENIX-6959) Server merges are not used for hinted uncovered indexes for wildcard selects on 5.1
[ https://issues.apache.org/jira/browse/PHOENIX-6959?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Istvan Toth updated PHOENIX-6959:
---------------------------------
Summary: Server merges are not used for hinted uncovered indexes for wildcard selects on 5.1 (was: Server merges are not used for hinted uncovered indexes for wildcard selects)
> Server merges are not used for hinted uncovered indexes for wildcard selects on 5.1
> -----------------------------------------------------------------------------------
>
> Key: PHOENIX-6959
> URL: https://issues.apache.org/jira/browse/PHOENIX-6959
> Project: Phoenix
> Issue Type: Bug
> Components: phoenix
> Affects Versions: 5.1.3
> Reporter: Istvan Toth
> Assignee: Istvan Toth
> Priority: Major
>
> When selecting all columns by specifying '*' phoenix uses a skip-scan-join for the query.
> When specifying each column individually, Phoenix uses the more efficient server merge plan.
> This is already fixed in 5.2
> Check if it is feasible to backport this optimization to 5.1
> -When selecting all columns by specifying '*', Phoenix performs a full table scan.-
> -Selecting all columns by specifying each one individually, Phoenix uses the uncovered index as intended.-
> {noformat}
> create table data_table (k integer primary key, v1 integer, v2 integer, v3 integer, v4 integer);
> create index uncovered on data_table (v1);
> explain select /*+ INDEX(data_table uncovered) */ k,v1,v2,v3,v4 from data_table where v1=1;
> +-------------------------------------------------------------------------+----------------+---------------+-------------+
> | PLAN | EST_BYTES_READ | EST_ROWS_READ | EST_INFO_TS |
> +-------------------------------------------------------------------------+----------------+---------------+-------------+
> | CLIENT 1-CHUNK PARALLEL 1-WAY ROUND ROBIN RANGE SCAN OVER UNCOVERED [1] | null | null | null |
> | SERVER MERGE [0.V2, 0.V3, 0.V4] | null | null | null |
> | SERVER FILTER BY FIRST KEY ONLY | null | null | null |
> +-------------------------------------------------------------------------+----------------+---------------+-------------+
> 3 rows selected (0.011 seconds)
> 0: jdbc:phoenix:localhost:49653> explain select /*+ INDEX(data_table uncovered) */ * from data_table where v1=1;
> +---------------------------------------------------------------------------------+----------------+---------------+-------------+
> | PLAN | EST_BYTES_READ | EST_ROWS_READ | EST_INFO_TS |
> +---------------------------------------------------------------------------------+----------------+---------------+-------------+
> | CLIENT 1-CHUNK PARALLEL 1-WAY ROUND ROBIN FULL SCAN OVER DATA_TABLE | null | null | null |
> | SKIP-SCAN-JOIN TABLE 0 | null | null | null |
> | CLIENT 1-CHUNK PARALLEL 1-WAY ROUND ROBIN RANGE SCAN OVER UNCOVERED [1] | null | null | null |
> | SERVER FILTER BY FIRST KEY ONLY | null | null | null |
> | DYNAMIC SERVER FILTER BY "DATA_TABLE.K" IN ($183.$185) | null | null | null |
> +---------------------------------------------------------------------------------+----------------+---------------+-------------+
> 5 rows selected (0.012 seconds)
> {noformat}
>
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