Istvan Toth created PHOENIX-6980:
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Summary: Push TopN down into joins where applicable
Key: PHOENIX-6980
URL: https://issues.apache.org/jira/browse/PHOENIX-6980
Project: Phoenix
Issue Type: Improvement
Reporter: Istvan Toth
This came up with an non-merging hinted uncovered index query, which may not be
directly applicable in the latest versions, but the same problem reproducible
with a simple IN subquery, which uses the same plan:
{noformat}
CREATE TABLE A(A_ID INTEGER NOT NULL PRIMARY KEY, A_V1 INTEGER);
CREATE TABLE B(B_ID INTEGER NOT NULL PRIMARY KEY, B_V1 INTEGER);
explain select * from A where (A_ID, A_V1) in (select B_ID, B_V1 from b ) order
by a_v1 limit 10;
+-----------------------------------------------------------------+----------------+---------------+-------------+
| PLAN |
EST_BYTES_READ | EST_ROWS_READ | EST_INFO_TS |
+-----------------------------------------------------------------+----------------+---------------+-------------+
| CLIENT 1-CHUNK PARALLEL 1-WAY FULL SCAN OVER A | null
| null | null |
| SERVER TOP 10 ROWS SORTED BY [A.A_V1] | null
| null | null |
| CLIENT MERGE SORT | null
| null | null |
| CLIENT LIMIT 10 | null
| null | null |
| SKIP-SCAN-JOIN TABLE 0 | null
| null | null |
| CLIENT 1-CHUNK PARALLEL 1-WAY FULL SCAN OVER B | null
| null | null |
| SERVER AGGREGATE INTO DISTINCT ROWS BY [B_ID, B_V1] | null
| null | null |
| CLIENT MERGE SORT | null
| null | null |
| DYNAMIC SERVER FILTER BY A.A_ID IN ($48.$50) | null
| null | null |
+-----------------------------------------------------------------+----------------+---------------+-------------+
{noformat}
This is super inefficient, the topN part should be pushed down into the inner
query.
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