I need to change a PRIMARY KEY CONSTRAINT in PostgreSql from a single to a composite key, using Scala's Play Framework Evolutions. This Change Primary Key post gives me a good head start, so I will adapt their example; suppose my db evolutions 1.sql file is:
-- !Ups
CREATE TABLE city (
city_id BIGSERIAL PRIMARY KEY,
group_id int,
"version" int
);
CREATE INDEX city__version ON city("version");
CREATE INDEX city__group_id ON city(group_id);
-- !Downs
DROP TABLE city;
I want to change the PK to include 2 more columns, like:
CREATE TABLE city (
city_id BIGSERIAL,
group_id int,
"version" int,
CONSTRAINT city_pk PRIMARY KEY (city_id, group_id, "version");
);
-- ...
I think the 2.sql file should look like:
-- !Ups
ALTER TABLE city
DROP COLUMN city_id,
ADD COLUMN city_id BIGSERIAL,
ADD CONSTRAINT city_pk PRIMARY KEY (city_id, group_id, "version");
-- !Downs
ALTER TABLE city
DROP CONSTRAINT city_pk,
DROP COLUMN city_id,
ADD COLUMN city_id BIGSERIAL PRIMARY KEY;
But I wonder if I need to truncate the table first*, since I'm dropping an essential column... If so, should I include a TRUNCATE command to the evolution file before the ALTER TABLE command? Otherwise, is there another way to change the PRIMARY KEY w/o DROP + ADD COLUMN?
* it's OK to do it on my use case.
Just tested my suggested changes and it worked. The 2.sql file is the same as suggested; there was no need to truncate the table first, and the original data was preserved, including the city_id:
-- !Ups
ALTER TABLE city
DROP COLUMN city_id,
ADD COLUMN city_id BIGSERIAL,
ADD CONSTRAINT city_pk PRIMARY KEY (city_id, group_id, "version");
-- !Downs
ALTER TABLE city
DROP CONSTRAINT city_pk,
DROP COLUMN city_id,
ADD COLUMN city_id BIGSERIAL PRIMARY KEY;
Related
I am trying to create a database with minimum redundancy in mind. We would like to use the timescaledb hypertables (I run postgreSQL v. 12 and timescaledb v. 1.7.4). The postgreSQL code to create the tables are as follows - you can see the dbdiagram here https://dbdiagram.io/d/5f992f0e3a78976d7b797ca2 or view the tables here Image of database
CREATE TABLE "datapoints" (
"id" bigserial UNIQUE NOT NULL,
"tstz" timestamptz NOT NULL,
"entity_id" bigint NOT NULL,
"value" real NOT NULL,
PRIMARY KEY ("tstz", "entity_id")
);
CREATE TABLE "datapoint_quality" (
"tstz" timestamptz NOT NULL,
"datapoint_id" bigint NOT NULL,
"flag_id" bigint NOT NULL,
PRIMARY KEY ("tstz", "datapoint_id", "flag_id")
);
CREATE TABLE "quality_flags" (
"id" bigserial PRIMARY KEY,
"value" text
);
CREATE TABLE "sensor_types" (
"id" bigserial PRIMARY KEY,
"name" text UNIQUE NOT NULL
);
CREATE TABLE "sensors" (
"tstz" timestamptz NOT NULL DEFAULT (now()),
"id" bigserial UNIQUE NOT NULL,
"name" text NOT NULL,
"parent" bigint NOT NULL,
"type" bigint NOT NULL,
PRIMARY KEY ("tstz", "id")
);
CREATE TABLE "datapoint_annotation" (
"tstz" timestamptz NOT NULL,
"datapoint_id" bigint NOT NULL,
"annotation_id" bigint NOT NULL,
PRIMARY KEY ("tstz", "datapoint_id", "annotation_id")
);
CREATE TABLE "annotations" (
"id" bigserial PRIMARY KEY NOT NULL,
"value" text NOT NULL
);
ALTER TABLE "datapoints" ADD FOREIGN KEY ("entity_id") REFERENCES "sensors" ("id");
ALTER TABLE "datapoint_quality" ADD FOREIGN KEY ("datapoint_id") REFERENCES "datapoints" ("id");
ALTER TABLE "datapoint_quality" ADD FOREIGN KEY ("flag_id") REFERENCES "quality_flags" ("id");
ALTER TABLE "sensors" ADD FOREIGN KEY ("parent") REFERENCES "sensors" ("id");
ALTER TABLE "sensors" ADD FOREIGN KEY ("type") REFERENCES "sensor_types" ("id");
ALTER TABLE "datapoint_annotation" ADD FOREIGN KEY ("datapoint_id") REFERENCES "datapoints" ("id");
ALTER TABLE "datapoint_annotation" ADD FOREIGN KEY ("annotation_id") REFERENCES "annotations" ("id");
CREATE UNIQUE INDEX ON "quality_flags" ("value");
CREATE UNIQUE INDEX ON "annotations" ("value");
So far so good - next I want to create the hypertables, which I do as:
SELECT create_hypertable('datapoint_annotation', 'tstz');
SELECT create_hypertable('datapoint_quality', 'tstz');
SELECT create_hypertable('datapoints', 'tstz');
SELECT create_hypertable('sensors', 'tstz');
This works well for the first two lines, but for the latter two I get the following error:
ERROR: cannot create a unique index without the column "tstz" (used in partitioning)
SQL state: TS103
I can include the tstz in the primary key as ("id", "tstz") and use that as foreign key, but this gives me a one-to-one relation, and for minimum redundancy I would like to have a one-to-many relation.
I am sure there should be some way to do this - so what am I missing?
I'll take the foreign key constraint from datapoint_quality to datapoints as an example.
To make that work with a partitioned table, you need a unique constraint on datapoint. As the error message tell you, such a constraint must contain the partitioning key. So you end up with
ALTER TABLE datapoints ADD UNIQUE (id, tstz);
To reference that unique constraint from datapoint_quality, you need to have the timestamp there too:
ALTER TABLE datapoint_quality ADD datapoints_tstz timestamp with time zone;
You have to fill it with the appropriate values:
UPDATE datapoint_quality AS dq
SET datapoints_tstz = d.tstz
FROM datapoints AS d
WHERE d.id = dq.datapoint_id;
Then set it NOT NULL:
ALTER TABLE datapoint_quality ALTER datapoints_tstz SET NOT NULL;
Now you can define your foreign key:
ALTER TABLE datapoint_quality
ADD FOREIGN KEY (datapoint_id, datapoints_tstz)
REFERENCES datapoints (id, tstz) MATCH FULL;
There is no other way to have foreign key constraints with partitioned tables.
After testing the proposed solution by Laurenz in a database I have and also after replicating the original database of this case. I use PostgreSQL 12.6 and timescaledb 1.7.5.
Basically, I arrived well until defining the Foreign Key for Table datapoint_quality:
ALTER TABLE datapoint_quality
ADD FOREIGN KEY (datapoint_id, datapoints_tstz)
REFERENCES datapoints (id, tstz) MATCH FULL;
The next error is present in both databases I've tested after several attempts (included above one) to define the foreign key to a hypertable:
ERROR: foreign keys to hypertables are not supported Blockquote SQL state: 0A000
According to https://docs.timescale.com/timescaledb/latest/overview/limitations/##distributed-hypertable-limitations, it looks like the above error is part of the hypertable limitations:
Foreign key constraints referencing a hypertable are not supported.
Considering this, does anyone know any solution at the DB level to establish the relationships (1..* or ...) among a table without hypertables to other tables with hypertables behind?
Maybe could be a solution to deal with this at even a REST API level (e.g. Django or Flask) given at timescaledb or PostgreSQL I have not found much more solutions.
I have one table that has two fields. The structure is like this:
CREATE TABLE raw_links
(
value_id bigint NOT NULL,
raw_id integer NOT NULL,
CONSTRAINT raw_links_pk PRIMARY KEY (raw_id, dp_id),
CONSTRAINT raw_fk FOREIGN KEY (raw_id)
REFERENCES raw_data (raw_data_id) MATCH SIMPLE
ON UPDATE RESTRICT ON DELETE RESTRICT
)
I have to delete 5 million records from this table. For that I want to disable both constraints so that deletion will be faster. After deletion I want to create both constraints.
You can do ALTER TABLE DROP CONSTRAINT raw_links_pk and the same for raw_fk.
After you delete the records, first do a VACUUM ANALYZE raw_links (or VACUUM FULL raw_links if you want to reclaim disk space), to update the table statistics.
Then finally rebuild the constraints with ALTER TABLE ADD CONSTRAINT ....
For the example.
Schema: source, Table: finalsales, Constrait: finalsales_pkey, Column: order_id.
--Disable Primary Key
ALTER TABLE source."finalsales" DROP CONSTRAINT finalsales_pkey;
--Enable Primary Key
ALTER TABLE source."finalsales"
ADD CONSTRAINT finalsales_pkey PRIMARY KEY ( order_id );
I have a table in postgresql with a composite primary key. The primary key consists of two columns named:
DATETIME, UID
I have a another (non-null) column named ACTION already existing in this table. How do I add ACTION to the composite primary key? Ie: I'd like the resulting primary key of the table to be the triplet:
DATETIME, UID, ACTION
First drop the primary key constraint. You can get the name of the constraint by typing
\d my_table
and look under indexes for something like:
"my_table_pkey" PRIMARY KEY, btree (datetime, uid)
Drop it by doing:
alter table my_table drop constraint my_table_pkey;
Then create the new composite primary key by doing:
alter table my_table add constraint my_table_pkey primary key (datetime, uid, action);
I have a column in db which has 5 columns but no primary key.
One of the columns is named myTable_id and is integer.
I want to check if the table has a primary key column. If it doesn't, then make myTable_id a primary key column and make it identity column. Is there a way to do this?
I tried with this:
ALTER TABLE Persons
DROP CONSTRAINT pk_PersonID
ALTER TABLE Persons
ADD PRIMARY KEY (P_Id)
and I get syntax error in Management studio.
This checks if primary key exists, if not it is created
IF NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE = 'PRIMARY KEY' AND TABLE_NAME = 'Persons'
AND TABLE_SCHEMA ='dbo')
BEGIN
ALTER TABLE Persons ADD CONSTRAINT pk_PersonID PRIMARY KEY (P_Id)
END
ELSE
BEGIN
-- Key exists
END
fiddle: http://sqlfiddle.com/#!6/e165d/2
ALTER TABLE Persons
ADD CONSTRAINT pk_PersonID PRIMARY KEY (P_Id)
An IDENTITY constraint can't be added to an existing column, so how you add this needs to be your initial thought. There are two options:
Create a new table including a primary key with identity and drop the existing table
Create a new primary key column with identity and drop the existing 'P_ID' column
There is a third way, which is a better approach for very large tables via the ALTER TABLE...SWITCH statement. See Adding an IDENTITY to an existing column for an example of each. In answer to this question, if the table isn't too large, I recommend running the following:
-- Check that the table/column exist and no primary key is already on the table.
IF COL_LENGTH('PERSONS','P_ID') IS NOT NULL
AND NOT EXISTS (SELECT 1 FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_TYPE = 'PRIMARY KEY' AND TABLE_NAME = 'PERSONS')
-- Add table schema to the WHERE clause above e.g. AND TABLE_SCHEMA ='dbo'
BEGIN
ALTER TABLE PERSONS
ADD P_ID_new int IDENTITY(1, 1)
GO
ALTER TABLE PERSONS
DROP COLUMN P_ID
GO
EXEC sp_rename 'PERSONS.P_ID_new', 'P_ID', 'Column'
GO
ALTER TABLE PERSONS
ADD CONSTRAINT PK_P_ID PRIMARY KEY CLUSTERED (P_ID)
GO
END
Notes:
By explicitly using the CONSTRAINT keyword the primary key constraint is given a particular name rather than depending on SQL Server to auto-assign a name.
Only include CLUSTERED on the PRIMARY KEY if the balance of searches for a particular P_ID and the amount of writing outweighs the benefits of clustering the table by some other index. See Create SQL IDENTITY as PRIMARY KEY.
You can check if primary key exists or not using OBJECTPROPERTY Transact SQL, use 'TableHasPrimaryKey' for the second arguments.
DECLARE #ISHASPRIMARYKEY INT;
SELECT #ISHASPRIMARYKEY = OBJECTPROPERTY(OBJECT_ID('PERSONS'), 'TABLEHASPRIMARYKEY');
IF #ISHASPRIMARYKEY IS NULL
BEGIN
-- generate identity column
ALTER TABLE PERSONS
DROP COLUMN P_ID;
ALTER TABLE PERSONS
ADD P_ID INT IDENTITY(1,1);
-- add primary key
ALTER TABLE PERSONS
ADD CONSTRAINT PK_PERSONID PRIMARY KEY (P_ID);
END;
I don't think you can do that. For making a column into an identity column I think you have to drop the table entirely.
I wanted to use timetravel function (F.39. spi, PostgreSQL 9.1 Documentation) in my application, however it doesn't seem to work properly for me. With inserting rows into table everything works just fine, I get start and stop date properly, but when I'm trying to update those rows postgres gives me error about violating of PRIMARY KEY constraint. He's trying to insert a tuple with the same primary id as previous tuple...
It's insane to remove primary key constraints from all tables in the database but it's the functionality I need. So maybe you have some expierience with timetravel?
Any sort of help will be appreciated. Thanks in advance.
DDL:
CREATE TABLE cities
(
city_id serial NOT NULL,
state_id integer,
name character varying(80) NOT NULL,
start_date abstime,
stop_date abstime,
CONSTRAINT pk_cities PRIMARY KEY (city_id ),
CONSTRAINT fk_cities_states FOREIGN KEY (state_id)
REFERENCES states (state_id) MATCH SIMPLE
ON UPDATE CASCADE ON DELETE NO ACTION
)
WITH (
OIDS=FALSE
);
-- Trigger: time_travel on cities
-- DROP TRIGGER time_travel ON cities;
CREATE TRIGGER time_travel
BEFORE INSERT OR UPDATE OR DELETE
ON cities
FOR EACH ROW
EXECUTE PROCEDURE timetravel('start_date', 'stop_date');
STATEMENT GIVEN:
INSERT INTO cities(
state_id, name)
VALUES (20,'Paris');
and that's ok. I get start_date and stop_date.
But by:
UPDATE cities SET name='Rome' WHERE name='Paris'
I get error- described earlier.
Schema of states
-- Table: states
-- DROP TABLE states;
CREATE TABLE states
(
state_id serial NOT NULL, -- unikatowy numer wojewodztwa
country_id integer, -- identyfikator panstwa, w ktorym znajduje sie wojewodztwo
name character varying(50), -- nazwa wojewodztwa
CONSTRAINT pk_states PRIMARY KEY (state_id ),
CONSTRAINT uq_states_state_id UNIQUE (state_id )
)
WITH (
OIDS=FALSE
);
Unfortunately,as a new user I'm not allowed to post images here.
You can see them there:
Sample data from table cities: korpusvictifrew.cba.pl/postgres_cities.png
Sample data from table states: korpusvictifrew.cba.pl/states_data.png
Time travel converts an UPDATE into an UPDATE of the old record's stop_date and an INSERT of a new one with the changed data plus an infinity stop_date. You can't have more than one record for city_id due to pk_cities. The time travel triggers do not allow you to break that requirement.
You cannot use this:
CONSTRAINT pk_cities PRIMARY KEY (city_id )
You must use this
CONSTRAINT pk_cities PRIMARY KEY (city_id, stop_date)