Questions tagged [sequence]

An object that can generate unique integers.

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4
votes
2answers
12k views

Reset every Oracle sequence to the MAX value of its target table PK?

I finally got around to migrating from MySQL to Oracle and was pleasantly surprised just how well of a job the SQLDeveloper Migration tool did. It even took my AUTOINCREMENT fields and created ...
14
votes
2answers
33k views

Resetting a SQL Server 2012 sequence

I'm in the process of testing and populating a specific table that leverages the SEQUENCE object. In this process I'm testing populating the table with tens of thousands of insert lines (as I'm ...
2
votes
1answer
1k views

Generating an arithmetic sequence

I would like to generate a named table in a WITH clause which will contain this arithmetic progression: ╔══════════╗ ║ mynumber ║ ╠══════════╣ ║ 0 ║ ║ 30 ║ ║ 60 ║ ║ 90 ║ ║ ...
0
votes
1answer
919 views

MySQL non-sequential primary key of certain length

what's the best way to create a non-sequential primary key of a certain length in MySQL? I'm looking to use the primary key as a 'Pin' number which real actual human people can use to refer to the ...
7
votes
3answers
15k views

Using the same sequence twice in a PL/SQL statement

I wrote the snippet of PL/SQL today: declare first_id number; second_id number; begin insert into table (sort_nr, text_id, unit_id) values(..., table_seq.nextval, table_seq.nextval) returning ...
3
votes
1answer
1k views

Oracle sequence generation performance during persists of large data sets

In the context of an Oracle sequence, when persisting > 200 million records, is there a performance hit on the database if the sequence cache is the default value of 10000? That is to say does ...
1
vote
1answer
124 views

Expanding contractions/number ranges into separate records [closed]

I am planning the migration of a directory of image files plus a FileMaker-database containing the corresponding metadata into an Imagic IMS database (formerly known as ImageAccess). The vendor ...
2
votes
4answers
2k views

Limiting Generated Sequence Values in Multi-table Insert

In Oracle, given the following objects: create table a (x number ); create table b (val number ); create table c (val number ); create sequence my_seq; Suppose I populate table a as follows: insert ...
1
vote
1answer
2k views

Create unique numeric token on PostgreSQL

I have a database where I want to generate unique tokens of six numeric characters. These tokens should be generated each time an invoice number is inserted in the invoice_no column. This would mean ...
3
votes
4answers
559 views

What free database software support sequences [closed]

I have a requirement that a database must support sequences. I know oracle and PostgreSQL support it. Are there any other free database software that support database sequences? it would be great if ...
12
votes
1answer
28k views

Most efficient way to add a serial column to a huge table

What's the fastest way to add a BIGSERIAL column to a huge table (~3 Bil. rows, ~ 174Gb)? EDIT: I want the column to be incremented values for existing rows (NOT NULL). I didn't set a fillfactor (...
0
votes
1answer
1k views

Can You Replicate Sequences

In SQL 2012 can you replicate sequence objects, and if so do changes to the sequence (including consumption of values) get replicated? If not is there a good reason why this was not included?
2
votes
1answer
7k views

Best practices for ensuring up to date sequences after table import

We perform weekly table moves between several schema using expdp and impdp. Some tables have sequences associated with the ID columns and I'd like to ensure that the sequences are always up to date on ...
11
votes
3answers
10k views

How could sequence.nextval be null in Oracle?

I have an Oracle sequence defined like so: CREATE SEQUENCE "DALLAS"."X_SEQ" MINVALUE 0 MAXVALUE 999999999999999999999999999 INCREMENT BY 1 START WITH 0 NOCACHE NOORDER NOCYCLE ; ...
2
votes
1answer
1k views

Using the special Dual table to read sequences

It there a performance impact when using the dual table to read a sequence' nextval over an direct insert? I'm currently optimizing the performance in a large IT system and what I've found is that ...
6
votes
1answer
1k views

Guarantee SQL Server Identity Columns that two consecutive values differ by constant increments?

I posed a question about Denali sequences here and another question about emulation of identity columns in Oracle Global Tables here. I always thought that I could trust that identity values ...
82
votes
10answers
275k views

How do I use currval() in PostgreSQL to get the last inserted id?

I have a table: CREATE TABLE names (id serial, name varchar(20)) I want the "last inserted id" from that table, without using RETURNING id on insert. There seem to be a function CURRVAL(), but I don'...
36
votes
2answers
4k views

Why are Denali sequences supposed to perform better than identity columns?

In his answer to Which is better: identity columns or generated unique id values? mrdenny says: When SQL Denali comes out it will support sequences which will be more efficient than identity, but ...

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