Examine the exhibit.
Which two are true concerning the execution plan?
Exhibit:
A. No partition-wise join is used
B. A full partition-wise join is used
C. A partial partition-wise join is used
D. The SALES table is composite partitioned
Correct Answer: BD
Explanation/Reference:
*The following example shows the execution plan for the full partition-wise join with the sales table range partitioned by time_id, and subpartitioned by hash on cust_id.
----------------------------------------------------------------------------------------------
| Id | Operation | Name | Pstart| Pstop |IN-OUT| PQ Distrib |
----------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | | | |
| 1 | PX COORDINATOR | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10001 | | | P->S | QC (RAND) |
|* 3 | FILTER | | | | PCWC | |
| 4 | HASH GROUP BY | | | | PCWP | |
| 5 | PX RECEIVE | | | | PCWP | |
| 6 | PX SEND HASH | :TQ10000 | | | P->P | HASH |
| 7 | HASH GROUP BY | | | | PCWP | |
| 8 | PX PARTITION HASH ALL | | 1 | 16 | PCWC | |
|* 9 | HASH JOIN | | | | PCWP | |
| 10 | TABLE ACCESS FULL | CUSTOMERS | 1 | 16 | PCWP | |
| 11 | PX PARTITION RANGE ITERATOR| | 8 | 9 | PCWC | |
|* 12 | TABLE ACCESS FULL | SALES | 113 | 144 | PCWP | |
----------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
3 - filter(COUNT(SYS_OP_CSR(SYS_OP_MSR(COUNT(*)),0))>100)
9 - access("S"."CUST_ID"="C"."CUST_ID")
12 - filter("S"."TIME_ID"<=TO_DATE(‘ 1999-10-01 00:00:00’, ‘syyyy-mm-dd hh24:mi:ss’) AND
"S"."TIME_ID">=TO_DATE(‘ 1999-07-01
00:00:00′, ‘syyyy-mm-dd hh24:mi:ss’))
*Full partition-wise joins can occur if two tables that are co-partitioned on the same key are joined in a query. The tables can be co-partitioned at the partition level, or at the subpartition level, or at a combination of partition and subpartition levels. Reference partitioning is an easy way to guarantee co-partitioning. Full partition-wise joins can be executed in serial and in parallel.
Reference: Oracle Database VLDB and Partitioning Guide, Full Partition-Wise Joins: Composite - Single-Level
Explanation/Reference:
*The following example shows the execution plan for the full partition-wise join with the sales table range partitioned by time_id, and subpartitioned by hash on cust_id.
----------------------------------------------------------------------------------------------
| Id | Operation | Name | Pstart| Pstop |IN-OUT| PQ Distrib |
----------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | | | |
| 1 | PX COORDINATOR | | | | | |
| 2 | PX SEND QC (RANDOM) | :TQ10001 | | | P->S | QC (RAND) |
|* 3 | FILTER | | | | PCWC | |
| 4 | HASH GROUP BY | | | | PCWP | |
| 5 | PX RECEIVE | | | | PCWP | |
| 6 | PX SEND HASH | :TQ10000 | | | P->P | HASH |
| 7 | HASH GROUP BY | | | | PCWP | |
| 8 | PX PARTITION HASH ALL | | 1 | 16 | PCWC | |
|* 9 | HASH JOIN | | | | PCWP | |
| 10 | TABLE ACCESS FULL | CUSTOMERS | 1 | 16 | PCWP | |
| 11 | PX PARTITION RANGE ITERATOR| | 8 | 9 | PCWC | |
|* 12 | TABLE ACCESS FULL | SALES | 113 | 144 | PCWP | |
----------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
3 - filter(COUNT(SYS_OP_CSR(SYS_OP_MSR(COUNT(*)),0))>100)
9 - access("S"."CUST_ID"="C"."CUST_ID")
12 - filter("S"."TIME_ID"<=TO_DATE(‘ 1999-10-01 00:00:00’, ‘syyyy-mm-dd hh24:mi:ss’) AND
"S"."TIME_ID">=TO_DATE(‘ 1999-07-01
00:00:00′, ‘syyyy-mm-dd hh24:mi:ss’))
*Full partition-wise joins can occur if two tables that are co-partitioned on the same key are joined in a query. The tables can be co-partitioned at the partition level, or at the subpartition level, or at a combination of partition and subpartition levels. Reference partitioning is an easy way to guarantee co-partitioning. Full partition-wise joins can be executed in serial and in parallel.
Reference: Oracle Database VLDB and Partitioning Guide, Full Partition-Wise Joins: Composite - Single-Level
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