Thread: Identity column data type difference in PostgreSQL and Oracle
Hello,
Tables which have an identity column in Oracle when migrated to PostgreSQL, the data type of Identity column is changed to bigint from number by the tools. This causes the size of column to be reduced to max value supported by bigint which is way lower than the oracle number max.
Secondly one has to change referencing columns data type as well.
What should be a better strategy for such transformations ?
CREATE TABLE Sales (
transaction_id NUMBER GENERATED ALWAYS AS IDENTITY MINVALUE 1 MAXVALUE <maxvaluefornumberdatatype> INCREMENT BY 1 START WITH 1 NOCYCLE
customer VARCHAR2(100),
transaction_date DATE,
store_id NUMBER
);
CREATE TABLE Sales_Details (
transaction_id NUMBER,
item VARCHAR2(100),
quantity NUMBER,
price NUMBER,
CONSTRAINT fk_transaction_id FOREIGN KEY (transaction_id) REFERENCES Sales(transaction_id)
);
--
Tables which have an identity column in Oracle when migrated to PostgreSQL, the data type of Identity column is changed to bigint from number by the tools. This causes the size of column to be reduced to max value supported by bigint which is way lower than the oracle number max.
Secondly one has to change referencing columns data type as well.
What should be a better strategy for such transformations ?
Sample tables
CREATE TABLE Sales (
transaction_id NUMBER GENERATED ALWAYS AS IDENTITY MINVALUE 1 MAXVALUE <maxvaluefornumberdatatype> INCREMENT BY 1 START WITH 1 NOCYCLE
customer VARCHAR2(100),
transaction_date DATE,
store_id NUMBER
);
CREATE TABLE Sales_Details (
transaction_id NUMBER,
item VARCHAR2(100),
quantity NUMBER,
price NUMBER,
CONSTRAINT fk_transaction_id FOREIGN KEY (transaction_id) REFERENCES Sales(transaction_id)
);
Regards,
Muhammad Ikram
On 03.05.24 12:57, Muhammad Ikram wrote: > Tables which have an identity column in Oracle when migrated to > PostgreSQL, the data type of Identity column is changed to bigint from > number by the tools. This causes the size of column to be reduced to max > value supported by bigint which is way lower than the oracle number max. Sequences in PostgreSQL are limited to bigint, there is nothing that can be changed about that. But you are approximately the first person to complain that the range of ids provided by bigint is too small, so maybe it's worth reconsidering whether it would work for you. If it really is too small, maybe a uuid would work. But yes, you'll need to make some adjustments to the rest of your database or application code if you make such changes.
Thanks for the advice.
On Fri, 3 May 2024 at 16:09, Peter Eisentraut <peter@eisentraut.org> wrote:
On 03.05.24 12:57, Muhammad Ikram wrote:
> Tables which have an identity column in Oracle when migrated to
> PostgreSQL, the data type of Identity column is changed to bigint from
> number by the tools. This causes the size of column to be reduced to max
> value supported by bigint which is way lower than the oracle number max.
Sequences in PostgreSQL are limited to bigint, there is nothing that can
be changed about that. But you are approximately the first person to
complain that the range of ids provided by bigint is too small, so maybe
it's worth reconsidering whether it would work for you. If it really is
too small, maybe a uuid would work. But yes, you'll need to make some
adjustments to the rest of your database or application code if you make
such changes.