Performs a hierarchical self-join
This operation was introduced in Oracle 8.1.7
This operation is implemented in the following versions
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In Oracle 8.1.7 only, the session parameter "_new_connect_by_enabled" must be set to true to generate plans using this operation
In Oracle 9.0.1 and above it is the default behaviour
This example was developed using Oracle 9.2.0.1 on Windows 2000
This example requires the following table and index definitions
CREATE TABLE t1 (c1 NUMBER,c2 NUMBER);
The table does not need to be analysed
In Oracle 8.1.7 only, the session parameter "_new_connect_by_enabled" must be set to true to generate plans using this operation
ALTER SESSION SET "_new_connect_by_enabled" = TRUE;
In Oracle 8.1.7 only, the statement
SELECT c1,c2 FROM t1 CONNECT BY c1 = c2 START WITH c1 = 0;
generates the following execution plan
0 SELECT STATEMENT Optimizer=CHOOSE 1 0 CONNECT BY (WITHOUT FILTERING) 2 1 TABLE ACCESS (FULL) OF 'T1'
In Oracle 10.2 the following execution plan was generated
0 SELECT STATEMENT Optimizer=CHOOSE 1 0 CONNECT BY (WITHOUT FILTERING) 2 1 FILTER 3 2 TABLE ACCESS (FULL) OF 'T1' 4 1 TABLE ACCESS (FULL) OF 'T1'
This operation has not yet been reproduced in Oracle 9.0.1 9.2 or 10.1