Best way to reset an Oracle sequence to the next value in an existing column?
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For some reason, people in the past have inserted data without using sequence.NEXTVAL. So when I go to use sequence.NEXTVAL in order to populate a table, I get a PK violation, since that number is already in use in the table.
How can I update the next value so that it is usable? Right now, I'm just inserting over and over until it's successful (
INSERT INTO tbl (pk) VALUES (sequence.NEXTVAL)), and that syncs up the nextval.
You can temporarily increase the cache size and do one dummy select and then reset the cache size back to 1. So for example
ALTER SEQUENCE mysequence INCREMENT BY 100; select mysequence.nextval from dual; ALTER SEQUENCE mysequence INCREMENT BY 1;
Best way to reset an Oracle sequence to the next value in an , Just click on the right for your comprehensive FREE training program to kick There is no "alter sequence reset" but you can, by playing with the increment by, to reset a sequence dynamically based on the maximum number in a column. COM> select s.nextval from dual; NEXTVAL ---------- 4 3) the way around this is TO� alter table your_table modify (id generated by default on null as identity start with limit value); Then the next insert will safely insert using a sequence that has been automatically reset to what is essentially max (id)+1 https://docs.oracle.com/database/121/SQLRF/statements_3001.htm#SQLRF01001. share.
These two procedures let me reset the sequence and reset the sequence based on data in a table (apologies for the coding conventions used by this client):
CREATE OR REPLACE PROCEDURE SET_SEQ_TO(p_name IN VARCHAR2, p_val IN NUMBER) AS l_num NUMBER; BEGIN EXECUTE IMMEDIATE 'select ' || p_name || '.nextval from dual' INTO l_num; -- Added check for 0 to avoid "ORA-04002: INCREMENT must be a non-zero integer" IF (p_val - l_num - 1) != 0 THEN EXECUTE IMMEDIATE 'alter sequence ' || p_name || ' increment by ' || (p_val - l_num - 1) || ' minvalue 0'; END IF; EXECUTE IMMEDIATE 'select ' || p_name || '.nextval from dual' INTO l_num; EXECUTE IMMEDIATE 'alter sequence ' || p_name || ' increment by 1 '; DBMS_OUTPUT.put_line('Sequence ' || p_name || ' is now at ' || p_val); END; CREATE OR REPLACE PROCEDURE SET_SEQ_TO_DATA(seq_name IN VARCHAR2, table_name IN VARCHAR2, col_name IN VARCHAR2) AS nextnum NUMBER; BEGIN EXECUTE IMMEDIATE 'SELECT MAX(' || col_name || ') + 1 AS n FROM ' || table_name INTO nextnum; SET_SEQ_TO(seq_name, nextnum); END;
How to reset sequences?, Oracle does not let you change the value of a sequence. If you need to change its value, you should re-create the sequence. On the other hand,� Best way to reset an Oracle sequence to the next value in an existing column? Related. 32. Dropping all user tables/sequences in Oracle. 0.
If you can count on having a period of time where the table is in a stable state with no new inserts going on, this should do it (untested):
DECLARE last_used NUMBER; curr_seq NUMBER; BEGIN SELECT MAX(pk_val) INTO last_used FROM your_table; LOOP SELECT your_seq.NEXTVAL INTO curr_seq FROM dual; IF curr_seq >= last_used THEN EXIT; END IF; END LOOP; END;
This enables you to get the sequence back in sync with the table, without dropping/recreating/re-granting the sequence. It also uses no DDL, so no implicit commits are performed. Of course, you're going to have to hunt down and slap the folks who insist on not using the sequence to populate the column...
How to Set Current Value of a Sequence Without Dropping , The Oracle ALTER SEQUENCE statement allows you to change the increment, minimum value, maximum value, cached numbers, and behavior of a sequence object. you will learn how to use the Oracle ALTER SEQUENCE statement to change of a sequence to a value that is less than the current sequence number . Best of all, it can be called to reset to a specified value, and just wait until you see the wrapper "fix all my sequences" procedure at the end. create or replace procedure Reset_Sequence( p_seq_name in varchar2, p_val in number default 0)
In my case I have a sequence called
PS_LOG_SEQ which had a
LAST_NUMBER = 3920.
I then imported some data from
PROD to my local machine and inserted into the
PS_LOG table. Production data had more than
20000 rows with the latest LOG_ID (primary key) being 20070. After importing I tried to insert new rows in this table but when saving I got an exception like this one:
ORA-00001: unique constraint (LOG.PS_LOG_PK) violated
Surely this has to do with the Sequence
PS_LOG_SEQ associated with the
PS_LOG table. The
LAST_NUMBER was colliding with data I imported which had already used the next ID value from the
To solve that I used this command to update the sequence to the latest \
max(LOG_ID) + 1:
alter sequence PS_LOG_SEQ restart start with 20071;
This command reset the
LAST_NUMBER value and I could then insert new rows into the table. No more collision. :)
alter sequence command is new in Oracle 12c.
Oracle ALTER SEQUENCE By Practical Examples, This Oracle tutorial explains how to create and drop sequences in Oracle with syntax and examples. In Oracle, you can create an autonumber field by using sequences. example, if the last value used by the Oracle sequence was 100 and you would like to reset the sequence to serve 225 as the next value. Back to top. just reset the value to be whatever "start with" value you want. say the sequence was created: create sequence s; and you are currently at 1,000 and want the sequence to now "start with 50", just use -950 instead of -1000 when you change the increment by to "reset" it.
With oracle 10.2g:
select level, sequence.NEXTVAL from dual connect by level <= (select max(pk) from tbl);
will set the current sequence value to the max(pk) of your table (i.e. the next call to NEXTVAL will give you the right result); if you use Toad, press F5 to run the statement, not F9, which pages the output (thus stopping the increment after, usually, 500 rows). Good side: this solution is only DML, not DDL. Only SQL and no PL-SQL. Bad side : this solution prints max(pk) rows of output, i.e. is usually slower than the ALTER SEQUENCE solution.
Oracle / PLSQL: Sequences (Autonumber), Introduction Since Oracle 12 we can declare columns as an identity column. The only decent way to see the current value is to set the sequence to nocache It might be a good idea to lock the table in exclusive mode during those steps. Updating an existing AUTO_INCREMENT column value in an� We are getting next auto incremented value from created sequence by selecting auto_increment_tb_seq.nextval and inserting it into :new row of table ID column. Best way to create auto increment column in oracle. Which is best way to insert auto incremented values into table? IDENTITY column or by using sequences and triggers?
SQL Quickie: How to reset an identity column – svenweller, UPDATE 2: Found some existing code in Moodle that resets the sequence, I had First you have to find out what the current sequence value is and then reset it. I'm pretty sure there are better scripts but if you have to do this task frequently this Of course you need to find a way to match the sequence name with the table� When creating a sequence, there is a lot of flexibility in how the sequence generates the next number using the Oracle NEXTVAL function: SQL> create sequence pubs2 2 start with 8 3 increment by 2 4 maxvalue 10000 5 cycle 6 cache 5; Sequence created. SQL> select pubs2.nextval from dual; NEXTVAL----- 8 . In the sequence example, the Oracle
How to set the sequence to the last used id for all tables in Oracle , This article demonstrates the common ways sequences can be used to DEFAULT Values for Table Columns : Enhancements in Oracle Database From Oracle 12c onward sequences can be defined as session-specific, so their current value is only relevant to the current session, and effectively reset Back to the Top. That way, you can find the sequences for the table column in the dba_sequences view. In Oracle 12c and beyond, you can associate a sequence directly with a table: In this example, we associate the sequence with the table, directly in the create table statement. create sequence my_test_id_seq increment by 1; create table
Oracle Sequences, Identity columns were introduced in Oracle 12c. This new feature allows you to specify that a column should be automatically populated from a supports the identity clause, but only to modify the attributes of EXISTING identity columns. In this case the highest value is 1004 so the next sequence number will be 1005. Specify the maximum value of the sequence. The max_value must be equal to or greater than first_number specify after the START WITH keywords. NOMAXVALUE. Use NOMAXVALUE to denote a maximum value of 10^27 for an ascending sequence or -1 for a descending sequence. Oracle uses this option as the default. MINVALUE. Specify the minimum value of the
- See this similar question
- @rationalSpring I ended up deciding to drop and recreate the sequence.
- The problem with dropping and recreating the sequence is that you have to re-apply any grants on it (not to mention that it temporarily invalidates any views or PL/SQL that refers to it).
- @JeffreyKemp Exactly, so after I did that, I came up with the routines in the self-answer I posted here and accepted.
- Sneaky. I like it.
- You may want to make sure no one else is using the sequence while it is changed.
- Please check out Leniel Macaferi's answer if you just simply want to reset the start value to a number.
alter sequence <seq> restart start with <num>;
- Does this work with 11g? I'm getting "Unknown set option ~~~"
- This works, it just needs an "END IF" after the IF line
- The doc you linked says "To restart the sequence at a different number, you must drop and re-create it.", no mention of the RESTART option. Wrong version linked?
- No: after running the select, current value of the sequence will be max(pk), so, when you need the next value of the sequence, calling sequence.NEXTVAL will give you the value of max(pk)+1. Anyway, try it: it's beautiful.
- This will always increment the sequence by however many rows you have in the table. If the sequence is not at 0, it will overshoot.