Related
I am trying to insert extracted data from a sql table into a postgres table where the rows may or may not exist. If they do exist, I would like to set a specific column to its default (0)
The table is as
site_notes (
job_id text primary key,
attachment_id text,
complete int default 0);
My query is
INSERT INTO site_notes (
job_id,
attachment_id
)
VALUES
{jobs_sql}
ON CONFLICT (job_id) DO UPDATE
SET complete = DEFAULT;
However I am getting an error: psycopg2.errors.CardinalityViolation: ON CONFLICT DO UPDATE command cannot affect row a second time
HINT: Ensure that no rows proposed for insertion within the same command have duplicate constrained values.
Would anyone be able to advise on how to set the complete column to the default on event of a conflict ?
Many Thanks
An INSERT ... ON CONFLICT DO UPDATE statement (and indeed an UPDATE statement too) is not allowed to modify the same row more than once. It is not clear what {jobs_sql} in your question is, but it must contain several rows, and at least two of those have the same job_id.
Make sure that the same job_id does not occur more than once in the rows you want to INSERT.
I have a question I know this was posted many times but I didn't find an answer to my problem. The problem is that I have a table and a column "id" I want it to be unique number just as normal. This type of column is serial and the next value after each insert is coming from a sequence so everything seems to be all right but it still sometimes shows this error. I don't know why. In the documentation, it says the sequence is foolproof and always works. If I add a UNIQUE constraint to that column will it help? I worked before many times on Postres but this error is showing for me for the first time. I did everything as normal and I never had this problem before. Can you help me to find the answer that can be used in the future for all tables that will be created? Let's say we have something easy like this:
CREATE TABLE comments
(
id serial NOT NULL,
some_column text NOT NULL,
CONSTRAINT id_pkey PRIMARY KEY (id)
)
WITH (
OIDS=FALSE
);
ALTER TABLE interesting.comments OWNER TO postgres;
If i add:
ALTER TABLE comments ADD CONSTRAINT id_id_key UNIQUE(id)
Will if be enough or is there some other thing that should be done?
This article explains that your sequence might be out of sync and that you have to manually bring it back in sync.
An excerpt from the article in case the URL changes:
If you get this message when trying to insert data into a PostgreSQL
database:
ERROR: duplicate key violates unique constraint
That likely means that the primary key sequence in the table you're
working with has somehow become out of sync, likely because of a mass
import process (or something along those lines). Call it a "bug by
design", but it seems that you have to manually reset the a primary
key index after restoring from a dump file. At any rate, to see if
your values are out of sync, run these two commands:
SELECT MAX(the_primary_key) FROM the_table;
SELECT nextval('the_primary_key_sequence');
If the first value is higher than the second value, your sequence is
out of sync. Back up your PG database (just in case), then run this command:
SELECT setval('the_primary_key_sequence', (SELECT MAX(the_primary_key) FROM the_table)+1);
That will set the sequence to the next available value that's higher
than any existing primary key in the sequence.
Intro
I also encountered this problem and the solution proposed by #adamo was basically the right solution. However, I had to invest a lot of time in the details, which is why I am now writing a new answer in order to save this time for others.
Case
My case was as follows: There was a table that was filled with data using an app. Now a new entry had to be inserted manually via SQL. After that the sequence was out of sync and no more records could be inserted via the app.
Solution
As mentioned in the answer from #adamo, the sequence must be synchronized manually. For this purpose the name of the sequence is needed. For Postgres, the name of the sequence can be determined with the command PG_GET_SERIAL_SEQUENCE. Most examples use lower case table names. In my case the tables were created by an ORM middleware (like Hibernate or Entity Framework Core etc.) and their names all started with a capital letter.
In an e-mail from 2004 (link) I got the right hint.
(Let's assume for all examples, that Foo is the table's name and Foo_id the related column.)
Command to get the sequence name:
SELECT PG_GET_SERIAL_SEQUENCE('"Foo"', 'Foo_id');
So, the table name must be in double quotes, surrounded by single quotes.
1. Validate, that the sequence is out-of-sync
SELECT CURRVAL(PG_GET_SERIAL_SEQUENCE('"Foo"', 'Foo_id')) AS "Current Value", MAX("Foo_id") AS "Max Value" FROM "Foo";
When the Current Value is less than Max Value, your sequence is out-of-sync.
2. Correction
SELECT SETVAL((SELECT PG_GET_SERIAL_SEQUENCE('"Foo"', 'Foo_id')), (SELECT (MAX("Foo_id") + 1) FROM "Foo"), FALSE);
Replace the table_name to your actual name of the table.
Gives the current last id for the table. Note it that for next step.
SELECT MAX(id) FROM table_name;
Get the next id sequence according to postgresql. Make sure this id is higher than the current max id we get from step 1
SELECT nextVal('"table_name_id_seq"');
if it's not higher than then use this step 3 to update the next sequence.
SELECT setval('"table_name_id_seq"', (SELECT MAX(id) FROM table_name)+1);
The primary key is already protecting you from inserting duplicate values, as you're experiencing when you get that error. Adding another unique constraint isn't necessary to do that.
The "duplicate key" error is telling you that the work was not done because it would produce a duplicate key, not that it discovered a duplicate key already commited to the table.
For future searchs, use ON CONFLICT DO NOTHING.
Referrence - https://www.calazan.com/how-to-reset-the-primary-key-sequence-in-postgresql-with-django/
I had the same problem try this:
python manage.py sqlsequencereset table_name
Eg:
python manage.py sqlsequencereset auth
you need to run this in production settings(if you have)
and you need Postgres installed to run this on the server
From http://www.postgresql.org/docs/current/interactive/datatype.html
Note: Prior to PostgreSQL 7.3, serial implied UNIQUE. This is no longer automatic. If you wish a serial column to be in a unique constraint or a primary key, it must now be specified, same as with any other data type.
In my case carate table script is:
CREATE TABLE public."Survey_symptom_binds"
(
id integer NOT NULL DEFAULT nextval('"Survey_symptom_binds_id_seq"'::regclass),
survey_id integer,
"order" smallint,
symptom_id integer,
CONSTRAINT "Survey_symptom_binds_pkey" PRIMARY KEY (id)
)
SO:
SELECT nextval('"Survey_symptom_binds_id_seq"'::regclass),
MAX(id)
FROM public."Survey_symptom_binds";
SELECT nextval('"Survey_symptom_binds_id_seq"'::regclass) less than MAX(id) !!!
Try to fix the proble:
SELECT setval('"Survey_symptom_binds_id_seq"', (SELECT MAX(id) FROM public."Survey_symptom_binds")+1);
Good Luck every one!
I had the same problem. It was because of the type of my relations. I had a table property which related to both states and cities. So, at first I had a relation from property to states as OneToOne, and the same for cities. And I had the same error "duplicate key violates unique constraint". That means that: I can only have one property related to one state and city. But that doesnt make sense, because a city can have multiple properties. So the problem is the relation. The relation should be ManyToOne. Many properties to One city
Table name started with a capital letter if tables were created by an ORM middleware (like Hibernate or Entity Framework Core etc.)
SELECT setval('"Table_name_Id_seq"', (SELECT MAX("Id") FROM "Table_name") + 1)
WHERE
NOT EXISTS (
SELECT *
FROM (SELECT CURRVAL(PG_GET_SERIAL_SEQUENCE('"Table_name"', 'Id')) AS seq, MAX("Id") AS max_id
FROM "Table_name") AS seq_table
WHERE seq > max_id
)
try that CLI
it's just a suggestion to enhance the adamo code (thanks a lot adamo)
SELECT setval('tableName_columnName_seq', (SELECT MAX(columnName) FROM tableName));
For programatically solution at Django. Based on Paolo Melchiorre's answer, I wrote a chunk as a function to be called before any .save()
from django.db import connection
def setSqlCursor(db_table):
sql = """SELECT pg_catalog.setval(pg_get_serial_sequence('"""+db_table+"""', 'id'), MAX(id)) FROM """+db_table+""";"""
with connection.cursor() as cursor:
cursor.execute(sql)
I have similar problem but I solved it by removing all the foreign key in my Postgresql
I have a table with existing data. Is there a way to add a primary key without deleting and re-creating the table?
(Updated - Thanks to the people who commented)
Modern Versions of PostgreSQL
Suppose you have a table named test1, to which you want to add an auto-incrementing, primary-key id (surrogate) column. The following command should be sufficient in recent versions of PostgreSQL:
ALTER TABLE test1 ADD COLUMN id SERIAL PRIMARY KEY;
Older Versions of PostgreSQL
In old versions of PostgreSQL (prior to 8.x?) you had to do all the dirty work. The following sequence of commands should do the trick:
ALTER TABLE test1 ADD COLUMN id INTEGER;
CREATE SEQUENCE test_id_seq OWNED BY test1.id;
ALTER TABLE test1 ALTER COLUMN id SET DEFAULT nextval('test_id_seq');
UPDATE test1 SET id = nextval('test_id_seq');
Again, in recent versions of Postgres this is roughly equivalent to the single command above.
ALTER TABLE test1 ADD COLUMN id SERIAL PRIMARY KEY;
This is all you need to:
Add the id column
Populate it with a sequence from 1 to count(*).
Set it as primary key / not null.
Credit is given to #resnyanskiy who gave this answer in a comment.
To use an identity column in v10,
ALTER TABLE test
ADD COLUMN id { int | bigint | smallint}
GENERATED { BY DEFAULT | ALWAYS } AS IDENTITY PRIMARY KEY;
For an explanation of identity columns, see https://blog.2ndquadrant.com/postgresql-10-identity-columns/.
For the difference between GENERATED BY DEFAULT and GENERATED ALWAYS, see https://www.cybertec-postgresql.com/en/sequences-gains-and-pitfalls/.
For altering the sequence, see https://popsql.io/learn-sql/postgresql/how-to-alter-sequence-in-postgresql/.
I landed here because I was looking for something like that too. In my case, I was copying the data from a set of staging tables with many columns into one table while also assigning row ids to the target table. Here is a variant of the above approaches that I used.
I added the serial column at the end of my target table. That way I don't have to have a placeholder for it in the Insert statement. Then a simple select * into the target table auto populated this column. Here are the two SQL statements that I used on PostgreSQL 9.6.4.
ALTER TABLE target ADD COLUMN some_column SERIAL;
INSERT INTO target SELECT * from source;
ALTER TABLE test1 ADD id int8 NOT NULL GENERATED ALWAYS AS IDENTITY;
I've never had to post a question on StackOverflow before because I can always find an answer here by just searching. Only this time, I think I've got a real stumper....
I'm writing code that automates the process of moving data from one SQL Server database to another. I have some pretty standard SQL Server Databases with foreign key relationships between some of their tables. Straight forward stuff. One of my requirements is that the entire table needs to be copied in one fell swoop, without looping through rows or using a cursor. Another requirement is I have to do this in SQL, no SSIS or other external helpers.
For example:
INSERT INTO TargetDatabase.dbo.MasterTable
SELECT * FROM SourceDatabase.dbo.MasterTable
That's easy enough. Then, once the data from the MasterTable has been moved, I move the data of the child table.
INSERT INTO TargetDatabase.dbo.ChildTable
SELECT * FROM SourceDatabase.dbo.ChildTable
Of course, in reality I use more explicit SQL... like I specifically name all the fields and things like that, but this is just a simplified version. Anyway, so far everything's going alright, except ...
The problem is that the primary key of the master table is defined as an identity field. So, when I insert into the MasterTable, the primary key for the new table gets calculated by the database. So to deal with that, I tried using the OUTPUT INTO statement to get the updated values into a Temp table:
INSERT INTO TargetDatabase.dbo.MasterTable
OUPUT INSERTED.* INTO #MyTempTable
SELECT * FROM SourceDatabase.dbo.MasterTable
So here's where it all falls apart. Since the database changed the primary key, how on earth do I figure out which record in the temp table matches up with the original record in the source table?
Do you see the problem? I know what the new ID is, I just don't know how to match it with the original record reliably. The SQL server lets me output the INSERTED values, but doesn't let me output the FROM TABLE values along side the INSERTED values. I've tried it with triggers, I've tried it with an SP, always I have the same problem.
If I were just updating one record at a time, I could easily match up my INSERTED values with the original record I was trying to insert to see the old and new primary key values, but I have this requirement to do it in a batch.
Any Ideas?
PS: I'm not allowed to change the table structure of the target or source table.
You can use MERGE.
declare #Source table (SourceID int identity(1,2), SourceName varchar(50))
declare #Target table (TargetID int identity(2,2), TargetName varchar(50))
insert into #Source values ('Row 1'), ('Row 2')
merge #Target as T
using #Source as S
on 0=1
when not matched then
insert (TargetName) values (SourceName)
output inserted.TargetID, S.SourceID;
Result:
TargetID SourceID
----------- -----------
2 1
4 3
Covered in this blog post by Adam Machanic: Dr. OUTPUT or: How I Learned to Stop Worrying and Love the MERGE
To illustrate what I mentioned in the comment:
SET IDENTITY_INSERT TargetDatabase.dbo.MasterTable ON
INSERT INTO TargetDatabase.dbo.MasterTable (IdentityColumn, OtherColumn1, OtherColumn2, ...)
SELECT IdentityColumn, OtherColumn1, OtherColumn2, ...
FROM SourceDatabase.dbo.MasterTable
SET IDENTITY_INSERT TargetDatabase.dbo.MasterTable OFF
Okay, since that didn't work for you (pre-existing values in target tables), how about adding a fixed increment (offset) to the id values in both tables (use the current max id value). Assuming the identity column is "id" in both tables:
DECLARE #incr int
BEGIN TRAN
SELECT #incr = max(id)
FROM TargetDatabase.dbo.MasterTable AS m WITH (TABLOCKX, HOLDLOCK)
SET IDENTITY_INSERT TargetDatabase.dbo.MasterTable ON
INSERT INTO TargetDatabase.dbo.MasterTable (id{, othercolumns...})
SELECT id+#incr{, othercolumns...}
FROM SourceDatabase.dbo.MasterTable
SET IDENTITY_INSERT TargetDatabase.dbo.MasterTable OFF
INSERT INTO TargetDatabase.dbo.ChildTable (id{, othercolumns...})
SELECT id+#incr{, othercolumns...}
FROM SourceDatabase.dbo.ChildTable
COMMIT TRAN
I have a question I know this was posted many times but I didn't find an answer to my problem. The problem is that I have a table and a column "id" I want it to be unique number just as normal. This type of column is serial and the next value after each insert is coming from a sequence so everything seems to be all right but it still sometimes shows this error. I don't know why. In the documentation, it says the sequence is foolproof and always works. If I add a UNIQUE constraint to that column will it help? I worked before many times on Postres but this error is showing for me for the first time. I did everything as normal and I never had this problem before. Can you help me to find the answer that can be used in the future for all tables that will be created? Let's say we have something easy like this:
CREATE TABLE comments
(
id serial NOT NULL,
some_column text NOT NULL,
CONSTRAINT id_pkey PRIMARY KEY (id)
)
WITH (
OIDS=FALSE
);
ALTER TABLE interesting.comments OWNER TO postgres;
If i add:
ALTER TABLE comments ADD CONSTRAINT id_id_key UNIQUE(id)
Will if be enough or is there some other thing that should be done?
This article explains that your sequence might be out of sync and that you have to manually bring it back in sync.
An excerpt from the article in case the URL changes:
If you get this message when trying to insert data into a PostgreSQL
database:
ERROR: duplicate key violates unique constraint
That likely means that the primary key sequence in the table you're
working with has somehow become out of sync, likely because of a mass
import process (or something along those lines). Call it a "bug by
design", but it seems that you have to manually reset the a primary
key index after restoring from a dump file. At any rate, to see if
your values are out of sync, run these two commands:
SELECT MAX(the_primary_key) FROM the_table;
SELECT nextval('the_primary_key_sequence');
If the first value is higher than the second value, your sequence is
out of sync. Back up your PG database (just in case), then run this command:
SELECT setval('the_primary_key_sequence', (SELECT MAX(the_primary_key) FROM the_table)+1);
That will set the sequence to the next available value that's higher
than any existing primary key in the sequence.
Intro
I also encountered this problem and the solution proposed by #adamo was basically the right solution. However, I had to invest a lot of time in the details, which is why I am now writing a new answer in order to save this time for others.
Case
My case was as follows: There was a table that was filled with data using an app. Now a new entry had to be inserted manually via SQL. After that the sequence was out of sync and no more records could be inserted via the app.
Solution
As mentioned in the answer from #adamo, the sequence must be synchronized manually. For this purpose the name of the sequence is needed. For Postgres, the name of the sequence can be determined with the command PG_GET_SERIAL_SEQUENCE. Most examples use lower case table names. In my case the tables were created by an ORM middleware (like Hibernate or Entity Framework Core etc.) and their names all started with a capital letter.
In an e-mail from 2004 (link) I got the right hint.
(Let's assume for all examples, that Foo is the table's name and Foo_id the related column.)
Command to get the sequence name:
SELECT PG_GET_SERIAL_SEQUENCE('"Foo"', 'Foo_id');
So, the table name must be in double quotes, surrounded by single quotes.
1. Validate, that the sequence is out-of-sync
SELECT CURRVAL(PG_GET_SERIAL_SEQUENCE('"Foo"', 'Foo_id')) AS "Current Value", MAX("Foo_id") AS "Max Value" FROM "Foo";
When the Current Value is less than Max Value, your sequence is out-of-sync.
2. Correction
SELECT SETVAL((SELECT PG_GET_SERIAL_SEQUENCE('"Foo"', 'Foo_id')), (SELECT (MAX("Foo_id") + 1) FROM "Foo"), FALSE);
Replace the table_name to your actual name of the table.
Gives the current last id for the table. Note it that for next step.
SELECT MAX(id) FROM table_name;
Get the next id sequence according to postgresql. Make sure this id is higher than the current max id we get from step 1
SELECT nextVal('"table_name_id_seq"');
if it's not higher than then use this step 3 to update the next sequence.
SELECT setval('"table_name_id_seq"', (SELECT MAX(id) FROM table_name)+1);
The primary key is already protecting you from inserting duplicate values, as you're experiencing when you get that error. Adding another unique constraint isn't necessary to do that.
The "duplicate key" error is telling you that the work was not done because it would produce a duplicate key, not that it discovered a duplicate key already commited to the table.
For future searchs, use ON CONFLICT DO NOTHING.
Referrence - https://www.calazan.com/how-to-reset-the-primary-key-sequence-in-postgresql-with-django/
I had the same problem try this:
python manage.py sqlsequencereset table_name
Eg:
python manage.py sqlsequencereset auth
you need to run this in production settings(if you have)
and you need Postgres installed to run this on the server
From http://www.postgresql.org/docs/current/interactive/datatype.html
Note: Prior to PostgreSQL 7.3, serial implied UNIQUE. This is no longer automatic. If you wish a serial column to be in a unique constraint or a primary key, it must now be specified, same as with any other data type.
In my case carate table script is:
CREATE TABLE public."Survey_symptom_binds"
(
id integer NOT NULL DEFAULT nextval('"Survey_symptom_binds_id_seq"'::regclass),
survey_id integer,
"order" smallint,
symptom_id integer,
CONSTRAINT "Survey_symptom_binds_pkey" PRIMARY KEY (id)
)
SO:
SELECT nextval('"Survey_symptom_binds_id_seq"'::regclass),
MAX(id)
FROM public."Survey_symptom_binds";
SELECT nextval('"Survey_symptom_binds_id_seq"'::regclass) less than MAX(id) !!!
Try to fix the proble:
SELECT setval('"Survey_symptom_binds_id_seq"', (SELECT MAX(id) FROM public."Survey_symptom_binds")+1);
Good Luck every one!
I had the same problem. It was because of the type of my relations. I had a table property which related to both states and cities. So, at first I had a relation from property to states as OneToOne, and the same for cities. And I had the same error "duplicate key violates unique constraint". That means that: I can only have one property related to one state and city. But that doesnt make sense, because a city can have multiple properties. So the problem is the relation. The relation should be ManyToOne. Many properties to One city
Table name started with a capital letter if tables were created by an ORM middleware (like Hibernate or Entity Framework Core etc.)
SELECT setval('"Table_name_Id_seq"', (SELECT MAX("Id") FROM "Table_name") + 1)
WHERE
NOT EXISTS (
SELECT *
FROM (SELECT CURRVAL(PG_GET_SERIAL_SEQUENCE('"Table_name"', 'Id')) AS seq, MAX("Id") AS max_id
FROM "Table_name") AS seq_table
WHERE seq > max_id
)
try that CLI
it's just a suggestion to enhance the adamo code (thanks a lot adamo)
SELECT setval('tableName_columnName_seq', (SELECT MAX(columnName) FROM tableName));
For programatically solution at Django. Based on Paolo Melchiorre's answer, I wrote a chunk as a function to be called before any .save()
from django.db import connection
def setSqlCursor(db_table):
sql = """SELECT pg_catalog.setval(pg_get_serial_sequence('"""+db_table+"""', 'id'), MAX(id)) FROM """+db_table+""";"""
with connection.cursor() as cursor:
cursor.execute(sql)
I have similar problem but I solved it by removing all the foreign key in my Postgresql