Istvan Toth created PHOENIX-6959:
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Summary: Hinted uncovered indexes are not used for wildcard selects
Key: PHOENIX-6959
URL: https://issues.apache.org/jira/browse/PHOENIX-6959
Project: Phoenix
Issue Type: Bug
Components: phoenix
Affects Versions: 5.1.3, 5.2.0
Reporter: Istvan Toth
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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