Currval question and confusion

Dear Group,
 my question:

I am using python scripts to create insert statements
for populating my tables.

First I fill table 1 and the primary key of table1 is
a FK in table2. Table2 PK is FK in Table3

I am filling in the following order:
Table 1

Take currval(table1_pk_seq) of ta table1 and write in
table2

Take currval in table2 and fill in the table3.

Now 3 people have simultaneously issued insert
statements. After some time while the second process
is still filling table 1 and enters table2 the currval
position has been changed. Then will I be assigning a
wrong FK in table2 and table3.

In this case Do i have to write any triggers.?

Please suggest some ideas.

thank you
k




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