What attribute of column I should use in order to get index value from postgresql sequence? valueNumeric? valueComputed?
As far as I understand the value of attribute should be nextval( 'simple_id_seq' ).
In postgresql sequence values are created as INTEGER or BIGINT.
Often this was done by using SERIAL or BIGSERIAL as column type ... but will indirectly create a sequencer of int or bigint and set the default value of the column to nextval(sequencer).
In a resultset of table data the column contains int or bigint.
Normaly there is no need to use nextval(sequencer) ... it fills the column on INSERT automatically (in the INSERT statemant the column shoult not appear).
Refer to http://www.postgresql.org/docs/9.3/static/datatype-numeric.html
If you do not want to use SERIAL or BIGSERIAL as suggested by #double_word_distruptor, use valueComputed.
With valueComputed you are telling Liquibase you are passing a function like nextval('simple_id_seq') and it will not try to parse it as a number or do any quoting.
You may also be able to use valueSequenceNext="simple_id_seq" to gain a little cross-database compatibility.
Related
In a Postgres 9.3 table I have an integer as primary key with automatic sequence to increment, but I have reached the maximum for integer. How to convert it from integer to serial?
I tried:
ALTER TABLE my_table ALTER COLUMN id SET DATA TYPE bigint;
But the same does not work with the data type serial instead of bigint. Seems like I cannot convert to serial?
serial is a pseudo data type, not an actual data type. It's an integer underneath with some additional DDL commands executed automatically:
Create a SEQUENCE (with matching name by default).
Set the column NOT NULL and the default to draw from that sequence.
Make the column "own" the sequence.
Details:
Safely rename tables using serial primary key columns
A bigserial is the same, built around a bigint column. You want bigint, but you already achieved that. To transform an existing serial column into a bigserial (or smallserial), all you need to do is ALTER the data type of the column. Sequences are generally based on bigint, so the same sequence can be used for any integer type.
To "change" a bigint into a bigserial or an integer into a serial, you just have to do the rest by hand:
Creating a PostgreSQL sequence to a field (which is not the ID of the record)
The actual data type is still integer / bigint. Some clients like pgAdmin will display the data type serial in the reverse engineered CREATE TABLE script, if all criteria for a serial are met.
I'm switching from MongoDB to PostgreSQL and was wondering how I can implement the same concept as used in MongoDB for uniquely identifying each raws by MongoId.
After migration, the already existing unique fields in our database is saved as character type. I am looking for minimum source code changes.
So if any way exist in postgresql for generating auto increment unique Id for each inserting into table.
The closest thing to MongoDB's ObjectId in PostgreSQL is the uuid type. Note that ObjectId has only 12 bytes, while UUIDs have 128 bits (16 bytes).
You can convert your existsing IDs by appending (or prepending) f.ex. '00000000' to them.
alter table some_table
alter id_column
type uuid
using (id_column || '00000000')::uuid;
Although it would be the best if you can do this while migrating the schema + data. If you can't do it during the migration, you need to update you IDs (while they are still varchars: this way the referenced columns will propagate the change), drop foreign keys, do the alter type and then re-apply foreign keys.
You can generate various UUIDs (for default values of the column) with the uuid-ossp module.
create extension "uuid-ossp";
alter table some_table
alter id_column
set default uuid_generate_v4();
Use a sequence as a default for the column:
create sequence some_id_sequence
start with 100000
owned by some_table.id_column;
The start with should be bigger then your current maximum number.
Then use that sequence as a default for your column:
alter table some_table
alter id_column set default nextval('some_id_sequence')::text;
The better solution would be to change the column to an integer column. Storing numbers in a text (or varchar) column is a really bad idea.
In a Postgres 9.3 table I have an integer as primary key with automatic sequence to increment, but I have reached the maximum for integer. How to convert it from integer to serial?
I tried:
ALTER TABLE my_table ALTER COLUMN id SET DATA TYPE bigint;
But the same does not work with the data type serial instead of bigint. Seems like I cannot convert to serial?
serial is a pseudo data type, not an actual data type. It's an integer underneath with some additional DDL commands executed automatically:
Create a SEQUENCE (with matching name by default).
Set the column NOT NULL and the default to draw from that sequence.
Make the column "own" the sequence.
Details:
Safely rename tables using serial primary key columns
A bigserial is the same, built around a bigint column. You want bigint, but you already achieved that. To transform an existing serial column into a bigserial (or smallserial), all you need to do is ALTER the data type of the column. Sequences are generally based on bigint, so the same sequence can be used for any integer type.
To "change" a bigint into a bigserial or an integer into a serial, you just have to do the rest by hand:
Creating a PostgreSQL sequence to a field (which is not the ID of the record)
The actual data type is still integer / bigint. Some clients like pgAdmin will display the data type serial in the reverse engineered CREATE TABLE script, if all criteria for a serial are met.
I'm using Grails 3.0.7 and Postgres 9.2. I'm very new to Postgres, so this may be a dumb question. How do I correctly associate an id generator sequence with a table? I read somewhere that if you create a table with an id column that has a serial datatype, then it will automatically create a sequence for that table.
However, the column seems to be created with a type of bigint. How do I get Grails to create the column with a bigserial datatype, and will this even solve my problem? What if I want one sequence per table? I'm just not sure how to go about setting this up because I've never really used Postgres in the past.
You can define a generator in a domain class like this:
static mapping = {
id generator:'sequence', params:[sequence:'domain_sq']
}
If the sequence is already present in the database then you'll need to name it in the params.
There are other properties also available as outlined in the documentation, for example:
static mapping = {
id column: 'book_id', type: 'integer'
}
In Postgres 10 or later consider an IDENTITY column instead. See:
Auto increment table column
However, the column seems to be created with a type of bigint. How do
I get Grails to create the column with a bigserial datatype, and will
this even solve my problem?
That's expected behavior. Define the column as bigserial, that's all you have to do. The Postgres pseudo data types smallserial, serial and bigserial create a smallint, int or bigint column respectively, and attach a dedicated sequence. The manual:
The data types smallserial, serial and bigserial are not true types,
but merely a notational convenience for creating unique identifier
columns (similar to the AUTO_INCREMENT property supported by some
other databases). In the current implementation, specifying:
CREATE TABLE tablename (
colname SERIAL
);
is equivalent to specifying:
CREATE SEQUENCE tablename_colname_seq;
CREATE TABLE tablename (
colname integer NOT NULL DEFAULT nextval('tablename_colname_seq')
);
ALTER SEQUENCE tablename_colname_seq OWNED BY tablename.colname;
Big quote, I couldn't describe it any better than the manual.
Related:
Get table and column "owning" a sequence
Safely rename tables using serial primary key columns
We're in process of converting over from SQL Server to Postgres. I have a scenario that I am trying to accommodate. It involves inserting records from one table into another, WITHOUT listing out all of the columns. I realize this is not recommended practice, but let's set that aside for now.
drop table if exists pk_test_table;
create table public.pk_test_table
(
recordid SERIAL PRIMARY KEY NOT NULL,
name text
);
--example 1: works and will insert a record with an id of 1
insert into pk_test_table values(default,'puppies');
--example 2: fails
insert into pk_test_table
select first_name from person_test;
Error I receive in the second example:
column "recordid" is of type integer but expression is of type
character varying Hint: You will need to rewrite or cast the
expression.
The default keyword will tell the database to grab the next value.
Is there any way to utilize this keyword in the second example? Or some way to tell the database to ignore auto-incremented columns and just them be populated like normal?
I would prefer to not use a subquery to grab the next "id".
This functionality works in SQL Server and hence the question.
Thanks in advance for your help!
If you can't list column names, you should instead use the DEFAULT keyword, as you've done in the simple insert example. This won't work with a in insert into ... select ....
For that, you need to invoke nextval. A subquery is not required, just:
insert into pk_test_table
select nextval('pk_test_table_id_seq'), first_name from person_test;
You do need to know the sequence name. You could get that from information_schema based on the table name and inferring its primary key, using a function that takes just the table name as an argument. It'd be ugly, but it'd work. I don't think there's any way around needing to know the table name.
You're inserting value into the first column, but you need to add a value in the second position.
Therefore you can use INSERT INTO table(field) VALUES(value) syntax.
Since you need to fetch values from another table, you have to remove VALUES and put the subquery there.
insert into pk_test_table(name)
select first_name from person_test;
I hope it helps
I do it this way via a separate function- though I think I'm getting around the issue via the table level having the DEFAULT settings on a per field basis.
create table public.pk_test_table
(
recordid integer NOT NULL DEFAULT nextval('pk_test_table_id_seq'),
name text,
field3 integer NOT NULL DEFAULT 64,
null_field_if_not_set integer,
CONSTRAINT pk_test_table_pkey PRIMARY KEY ("recordid")
);
With function:
CREATE OR REPLACE FUNCTION func_pk_test_table() RETURNS void AS
$BODY$
INSERT INTO pk_test_table (name)
SELECT first_name FROM person_test;
$BODY$
LANGUAGE sql VOLATILE;
Then just execute the function via a SELECT FROM func_pk_test_table();
Notice it hasn't had to specify all the fields- as long as constraints allow it.