I am working on postgres, I have 2 databases in the same server/instance, DB1 and DB2.
In DB2 I have my schema1.person table
Create table schema1.person (
person_id int primary key,
name varchar(20)
);
In DB1 I have this table
Create table schemaX.orders (
OrderId int primary key,
notes text,
person_id,
CONSTRAINT "fk person.id to order.person"
FOREIGN KEY (person_id) REFERENCES "DB2".schema1.person (person_id)
)
orders has a fk from another database, and when I ran this showed me this error on PG-ADMIN:
ERROR: cross-database references are not implemented: "DB2"
SQL state: 0A000
Any idea how I can solve this issue? and make fk from different databases, I have more tables with this scenario.
Related
I am trying to create a foreign key called 'user_id' for a 'transactions' table where the user_id references the 'user_accounts' table 'id' column. I keep getting an error when I execute the script that says:
SQL Error [42P01]: ERROR: relation "user_accounts" does not exist
The table clearly exists as I have been populating the user_accounts table with data that can be viewed in dbeaver. I am using Postgres and I am aware that quotes/capitalization can really make things difficult but I have executed my entire script without capitalizing or using quotes on any of the table or column names. Although, I did capitalize some of my column data types and I am wondering if that is the issue here? If so, what direction should I take to get my foreign key to work?
My script:
create table if not exists user_accounts (
id serial primary key,
first_name VARCHAR(30),
last_name VARCHAR(30),
username VARCHAR(20),
password VARCHAR(20),
deposit INT,
creditScore INT
)
create table if not exists transactions (
transaction_id serial primary key,
user_id INT references user_accounts(id) not null,
transaction_type VARCHAR(20),
amount INT
)
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 am new to SQL and am attempted to create a table, then alter the table to add some constraints with ALTER and finally insert 2 employees, one managing the other.
I have been getting this error in pgAdmin4 "ERROR: syntax error at or near "INSERT"
If anyone could let me know any other obvious issues in my code that would be great
Here is the table:
CREATE TABLE employee (
emp_id integer NOT NULL,
first_name varchar(15) NOT NULL,
last_name varchar(15) NOT NULL,
manager integer
);
And the altering:
ALTER TABLE employee ADD CONSTRAINT unique_emp_id UNIQUE (emp_id);
ALTER TABLE employee ADD FOREIGN KEY (manager) REFERENCES emp_id;
ALTER TABLE employee ADD CHECK (emp_id != manager)
INSERT INTO employee VALUES
(1, 'Tom', 'Jones', 2);
INSERT INTO employee (emp_id, first_name, last_name)
VALUES (2, 'Dave', 'Smith');
The foreign key reference needs to mention the table, even for a self-reference:
ALTER TABLE employee ADD FOREIGN KEY (manager) REFERENCES employee(emp_id);
In addition, the first insert doesn't work because the table is empty, so the foreign key fails. The inserts are in the wrong order. You should also list all the columns for an insert, even when you think you know them.
Here is a SQL Fiddle with the rest of the statements working.
I want to create a foreign key in my postgresql db table but i'm receiving still message about non existing table (???!!?) It's driving me crazy because I have created necessary relation (address).
CREATE TABLE base_schema.station
(
id SERIAL PRIMARY KEY NOT NULL,
phone VARCHAR(20) NOT NULL,
station_address INT NOT NULL,
CONSTRAINT station_address_id_fk FOREIGN KEY (station_address)
REFERENCES address (id)
);
CREATE UNIQUE INDEX station_id_uindex ON base_schema.station (id);
I'm using jetbrains datagrip
Thanks in advance
I have a foreign table, for example:
CREATE FOREIGN TABLE film (
id varchar(40) NOT NULL,
title varchar(40) NOT NULL,
did integer NOT NULL,
date_prod date,
kind varchar(10),
len interval hour to minute
)
SERVER film_server;
with id as the primary key for that table (set in the remote database). I would like to have a local table reference the foreign table, and set a foreign key constraint on the local table -- for example:
CREATE TABLE actor (
id varchar(40) NOT NULL,
name varchar(40) NOT NULL,
film_id varchar(40) NOT NULL,
)
ALTER TABLE actor ADD CONSTRAINT actor_film_fkey FOREIGN KEY (film_id)
REFERENCES film(id);
However, when I try to add the foreign key constraint, I get the error:
ERROR: referenced relation "film" is not a table
Is it possible to add a foreign key constraint to a foreign table?
It's no possible create index on foreign tables.
CREATE INDEX idx_film ON film (id);
This is the error:
ERROR: cannot create index on foreign table