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How to change my primary key from bigint (int64) to int (int32)?

Posted on 2010-08-12
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Last Modified: 2012-05-10
Experts,

I want to change my primary key from bigint (int64) to int (int32). My old table schema was: CREATE TABLE table_old (mykey_old bigint(20), PRIMARY KEY (mykey_old)); I want to convert it to CREATE TABLE table_new (mykey_new int(11), PRIMARY KEY (mykey_new));

The old table has several data. For example: 1437900001132237672, 1437900001132292609, 1437900001133420533, 1437900001134147674, etc.
The new table data should be: 32237672, 32292609, 33420533, 34147674, etc. Another problem is the new data may contain duplicate and I need to create random value to replace the duplicates.

Any step ideas to convert it smoothly?

Thank you.
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Question by:tikusbalap
  • 5
7 Comments
 
LVL 61

Expert Comment

by:HainKurt
ID: 33426391
which version of sql are u using?
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LVL 61

Expert Comment

by:HainKurt
ID: 33426406
this will create new table (remove duplicates)

select * into table_new from (
select * from (
select row_number() over (partititon by my_key old order by my_key old) rn, *
from table_old
) x where rn=1
)
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LVL 61

Expert Comment

by:HainKurt
ID: 33426419
then update  table_new

set my_key = my_key % 10000000

then

alter my_table
alter column my_key int;

then add PK to your table
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LVL 11

Expert Comment

by:JoeNuvo
ID: 33426458
There are few ways for you to go, depend on how do you want your old key to become

if just by yr example, you may insert into new table (or update old table)
by set value of mykey_new with value of (mykey_old - 14379000011)

or you may find MIN(mykey_old) and set value of mykey_new with value of (mykey_old - [old key min value])

or if you create new table and your primary key is "auto number",  you may just insert data into it
to let primary key start from any seed value you defined (usually start from 1)
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LVL 61

Expert Comment

by:HainKurt
ID: 33426471
before adding a pk

run this many times ;) hopefully once

update  table_new
set my_key=cast(10000000 * RAND(another_number_column_in_your_table) as int)
where m_key in (
  select m_key from table_new group by m_key having count(1) > 1
)
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LVL 6

Author Comment

by:tikusbalap
ID: 33427171
@HainKurt
How to update with RAND() function in my old table? I counter duplicate errors many times.
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LVL 61

Accepted Solution

by:
HainKurt earned 2000 total points
ID: 33432094
first run the update until you do not get any duplicates

if you get emty result from this (testing duplicates)

select m_key from table_new group by m_key having count(1) > 1

run this if you get any duplicates

update  table_new
set my_key=cast(10000000 * RAND(another_number_column_in_your_table*RAND(another_number_column_in_your_table)) as int)
where m_key in (
  select m_key from table_new group by m_key having count(1) > 1
)

add PK when tehre is no duplicates...
sample code

select cast(10 + 90*rand(num*1000*rand(num)) as int) new_id, * from dupid
35	12	634	a
87	13	235	b
27	13	334	g
54	15	356	t
27	11	334	u
16	12	764	b
41	14	856	d
99	12	467	y

select cast(10 + 90*rand(num*1000*rand(num)) as int) new_id, * from dupid
where id in (select id from dupId group by id having COUNT(1) >1)
35	12	634	a
87	13	235	b
27	13	334	g
16	12	764	b
99	12	467	y

update dupId
set id = cast(10 + 90*rand(num*1000*rand(num)) as int)
where id in (select id from dupId group by id having COUNT(1) >1)

(null)

select * from dupid
35	634	a
87	235	b
27	334	g
15	356	t
11	334	u
16	764	b
14	856	d
99	467	y

done!

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