SQL> show view v_cross_m;
TID_A                           INTEGER Expression
VN_A                            VARCHAR(80) Expression
ID_A                            INTEGER Expression
F1_A                            INTEGER Expression
F2_A                            INTEGER Expression
TID_B                           INTEGER Expression
VN_B                            VARCHAR(80) Expression
ID_B                            INTEGER Expression
F1_B                            INTEGER Expression
F2_B                            INTEGER Expression
View Source:
==== ======

    with c as(
        select
            c.mon$transaction_id tid
            ,substring(c.mon$variable_name from 3) vn
            ,min(cast( iif( c.mon$variable_name starting with 'ID_NEW', c.mon$variable_value, null) as int) ) ctx_id_new
            ,min(cast( iif( c.mon$variable_name starting with 'F1_NEW', c.mon$variable_value, null) as int) ) ctx_f1_new
            ,min(cast( iif( c.mon$variable_name starting with 'F2_NEW', c.mon$variable_value, null) as int) ) ctx_f2_new
        from mon$context_variables c
        group by 1,2
    )
    select
     ca.tid tid_a, ca.vn vn_a, ca.ctx_id_new id_a, ca.ctx_f1_new f1_a, ca.ctx_f2_new f2_a
    ,cb.tid tid_b, cb.vn vn_b, cb.ctx_id_new id_b, cb.ctx_f1_new f1_b, cb.ctx_f2_new f2_b
    from c ca join c cb
        on ca.ctx_id_new<>cb.ctx_id_new
            and sign(ca.ctx_f1_new - cb.ctx_f2_new) * sign(cb.ctx_f1_new - ca.ctx_f2_new)>0


SQL> select count(*) from mon$context_variables;

       COUNT
============
        1800

SQL> set stat on;
SQL> set plan on; select count(*) from v_cross_m;

PLAN JOIN (SORT (MON$CONTEXT_VARIABLES NATURAL), SORT (MON$CONTEXT_VARIABLES NATURAL))

PLAN JOIN (SORT (V_CROSS_M CA C NATURAL), SORT (V_CROSS_M CB C NATURAL))

Current memory = 1379592
Delta memory = 204840
Max memory = 3089480
Elapsed time= 113.56 sec
Buffers = 75
Reads = 12
Writes 0
Fetches = 205

SQL> select
CON>     c.mon$transaction_id tid
CON>     ,substring(c.mon$variable_name from 3) vn
CON>     ,min(cast( iif( c.mon$variable_name starting with 'ID_NEW', c.mon$variable_value, null) as int) ) ctx_id_new
CON>     ,min(cast( iif( c.mon$variable_name starting with 'F1_NEW', c.mon$variable_value, null) as int) ) ctx_f1_new
CON>     ,min(cast( iif( c.mon$variable_name starting with 'F2_NEW', c.mon$variable_value, null) as int) ) ctx_f2_new
CON> from mon$context_variables c
CON> group by 1,2;
Current memory = 1399376
Delta memory = 19704
Max memory = 3089480
 Elapsed time= 0.36 sec 
Buffers = 75
Reads = 0
Writes 0
Fetches = 0