question stringlengths 11 28.2k | answer stringlengths 26 27.7k | tag stringclasses 130
values | question_id int64 935 78.4M | score int64 10 5.49k |
|---|---|---|---|---|
Running a worker on a different machine results in errors specified below. I have followed the configuration instructions and have sync the dags folder.
I would also like to confirm that RabbitMQ and PostgreSQL only needs to be installed on the Airflow core machine and does not need to be installed on the workers (the ... | The ImportError: No module named postgresql error is due to the invalid prefix used in your celery_result_backend. When using a database as a Celery backend, the connection URL must be prefixed with db+. See
https://docs.celeryproject.org/en/stable/userguide/configuration.html#conf-database-result-backend
So replace:
... | RabbitMQ | 37,785,061 | 22 |
I've done a ton of research on this, and I'm surprised I haven't found a good answer to this yet anywhere.
I'm running a large application on Heroku, and I have certain celery tasks that run for a very long time processing, and at the end of the task save a result. Every time I redeploy on Heroku, it sends SIGTERM (and... | Starting in version >= 4, Celery comes with a special feature, just for Heroku, that supports this functionality out of the box:
$ REMAP_SIGTERM=SIGQUIT celery -A proj worker -l info
source: https://devcenter.heroku.com/articles/celery-heroku#using-remap_sigterm
| RabbitMQ | 29,872,998 | 22 |
Is there a way to get the size (remaining messages) of a queue in rabbitmq with a simple Curl?
Something like curl -xget http://host:1234/api/queue/test/stats
Thank you
| Finally I did the trick with the following:
curl -s -i -u guest:guest http://host:port/api/queues/vhost/queue_name | sed 's/,/\n/g' | grep '"messages"' | sed 's/"messages"://g'
| RabbitMQ | 24,402,399 | 22 |
I am running code on python to send and receive from RabbitMQ queue from another application where I can't allow threading.
This is very newbie question but, is there a possibility to just check if there is message and if there are no any then just quit listening ? How should I change basic "Hello world" example for s... | Ok, I found following solution:
def receive():
parameters = pika.ConnectionParameters(RabbitMQ_server)
connection = pika.BlockingConnection(parameters)
channel = connection.channel()
channel.queue_declare(queue='toM')
method_frame, header_frame, body = channel.basic_get(queue = 'toM')
if... | RabbitMQ | 9,876,227 | 22 |
Is there a way to determine if any task is lost and retry it?
I think that the reason for lost can be dispatcher bug or worker thread crash.
I was planning to retry them but I'm not sure how to determine which tasks need to be retired?
And how to make this process automatically? Can I use my own custom scheduler wh... | What you need is to set
CELERY_ACKS_LATE = True
Late ack means that the task messages will be acknowledged after the task has been executed,
not just before, which is the default behavior.
In this way if the worker crashes rabbit MQ will still have the message.
Obviously of a total crash (Rabbit + workers) at the same... | RabbitMQ | 5,336,645 | 22 |
I'm trying to use rabbitmq for a django tutorial but when I want to start the server I get this error:
~$ sudo rabbitmq-server
Configuring logger redirection
14:49:57.041 [error]
14:49:57.044 [error] BOOT FAILED
BOOT FAILED
14:49:57.044 [error] ===========
===========
14:49:57.044 [error] ERROR: could not bind to di... | Try:
sudo lsof -i :25672
sudo kill <PID>
sudo rabbitmq-server
Where <PID> is the process ID that is occupying port 25672
| RabbitMQ | 63,263,177 | 21 |
When I set permissions to the rabbitmq user, there is output the vhost:
[root@ha-node1 my.cnf.d]# rabbitmqctl set_permissions openstack ".*" ".*" ".*"
Setting permissions for user "openstack" in vhost "/" ...
What is the meaning of the vhost when I set permission, and what function does it have?
| In RabbitMQ virtual hosts are logical groups of entities, they are similar to virtual hosts in Apache or server blocks in Nginx.
Virtual hosts are created using rabbitmqctl or HTTP API and they provide logical grouping and separation of resources.
Every virtual host has a name. When an AMQP 0-9-1 client connects to Rab... | RabbitMQ | 45,250,282 | 21 |
From spring boot tutorial:
https://spring.io/guides/gs/messaging-rabbitmq/
They give an example of creating 1 queue and 1 queue only, but, what if I want to be able to create more then 1 queue? how would it be possible?
Obviously, I can't just create the same bean twice:
@Bean
Queue queue() {
return new Queue(queue... | Give the bean definition factory methods different names. Usually, by convention, you would name them the same as the queue, but that's not required...
@Bean
Queue queue1() {
return new Queue(queueNameAAA, false);
}
@Bean
Queue queue2() {
return new Queue(queueNameBBB, false);
}
The method name is the bean n... | RabbitMQ | 41,210,688 | 21 |
I've done a lot of searching but I cannot fix this issue.
I have a basic Rabbitmq container running via this command:
docker run -d --hostname rabbitmqhost --name rabbitmq -p 15672:15672 -p 5672:5672 rabbitmq:3-management
I am using nameko to create a microservice which connects to this container. Here's a basic micr... | If you're running a service inside a container, then amqp://guest:guest@localhost won't do you any good; localhost refers to the network namespace of the container...so of course you get an ECONNREFUSED, because there's nothing listening there.
If you want to connect to a service in another container, you need to use t... | RabbitMQ | 40,563,469 | 21 |
I want to scale my Node.js Socket application vertically and horizontally and I haven´t found a sophisticated solution yet.
My application has two use-cases:
Broadcast messages from one user to all others
Push messages from one user to a subset of users
On one hand, I´ve read that I need Redis for both cases togethe... | I'd say Kafka is a good fit for the horizontal scaling. It is a fairly sophisticated way of distributing a huge amount of events across servers (which at the end is what you want). This is a good read about it: https://engineering.linkedin.com/kafka/running-kafka-scale
Regarding the vertical scale, instead of socket.io... | RabbitMQ | 37,116,615 | 21 |
I've set up RabbitMQ in order to parse some 20.000 requests from an external API but it keeps timing out after a few minutes. It does get to correctly parse about 2000 out of the total 20.000 requests.
The log file says:
=INFO REPORT==== 16-Feb-2016::17:02:50 ===
accepting AMQP connection <0.1648.0> (127.0.0.1:33091 ->... | I've just solved a similar problem in python. In my case, it was solved by reducing the prefetch count on the consumer, so that it had fewer messages queued up in its receive buffer.
My theory is that the receive buffer on the consumer gets full, and then RMQ tries to write some other message to the consumer's socket a... | RabbitMQ | 35,438,843 | 21 |
I am trying to create integration test for a Scala / Java application that connects to a RabbitMQ broker. To achieve this I would like an embedded broker that speaks AMQP that I start and stop before each test. Originally I tried to introduce ActiveMQ as an embedded broker with AMQP however the application uses RabbitM... | A completely in-memory solution. Replace the spring.* properties as required.
<dependency>
<groupId>org.apache.qpid</groupId>
<artifactId>qpid-broker</artifactId>
<version>6.1.1</version>
<scope>test</scope>
</dependency>
public class EmbeddedBroker {
public void start() {
Broker broker = new Broker();
... | RabbitMQ | 30,918,557 | 21 |
I am using rabbitmctl using pika library.
I use the following code to create a Producer
#!/usr/bin/env python
import pika
import time
import json
import datetime
connection = pika.BlockingConnection(pika.ConnectionParameters(
host='localhost'))
channel = connection.channel()
channel.queue_declare(queue='he... | Since this seems to be a maintenance procedure, and not something you'll be doing routinely on your code, you should probably be using the RabbitMQ management plugin and delete the queue from there.
Anyway, you can delete it from pika with:
channel.queue_delete(queue='hello')
https://pika.readthedocs.org/en/latest/mo... | RabbitMQ | 19,912,344 | 21 |
I have Celery running with RabbitMQ broker.
Today, I have a failure of a Celery node, it doesn't execute tasks and doesn't respond on service celeryd stop command. After few repeats, the node stopped, but on start I get this message:
[WARNING/MainProcess] celery@nodename ready.
[WARNING/MainProcess] /home/ubuntu/virtua... | From here http://celery.readthedocs.org/en/latest/userguide/workers.html#starting-the-worker you might need to name each node uniquely. Example:
$ celery -A proj worker --loglevel=INFO --concurrency=10 -n worker1.%h
In supervisor escape by using %%h.
| RabbitMQ | 18,673,319 | 21 |
I know that there are similar questions to this, such as:
https://stackoverflow.com/questions/8232194/pros-and-cons-of-celery-vs-disco-vs-hadoop-vs-other-distributed-computing-packag
Differentiate celery, kombu, PyAMQP and RabbitMQ/ironMQ
but I'm asking this because I'm looking for a more particular distinction backe... |
They are the same in that both can solve the problem that you describe (map-reduce). They are different in that Hadoop is entirely build to solve only that usecase and Celey/RabbitMQ is build to facilitate Task execution on different nodes using message passing. Celery also supports different usecases.
Hadoop is solvi... | RabbitMQ | 18,521,196 | 21 |
It looks like celery does not release memory after task finished. Every time a task finishes, there would be 5m-10m memory leak. So with thousands of tasks, soon it will use up all memory.
BROKER_URL = 'amqp://user@localhost:5672/vhost'
# CELERY_RESULT_BACKEND = 'amqp://user@localhost:5672/vhost'
CELERY_IMPORTS = (
... | There are two settings which can help you mitigate growing memory consumption of celery workers:
Max tasks per child setting (v2.0+):
With this option you can configure the maximum number of tasks a worker can execute before it’s replaced by a new process. This is useful if you have memory leaks you have no control... | RabbitMQ | 17,541,452 | 21 |
I'm trying to get a Django Celery worker to connect to a RabbitMQ server, all running on the same host.
However, when I run manage.py celery worker all I get is:
[2013-06-11 17:33:41,185: WARNING/MainProcess] celery@localhost has started.
[2013-06-11 17:33:44,192: ERROR/MainProcess] Consumer: Connection Error: Socket c... | It looks like you need to grant access to the "/myapp" vhost for the "guest" user.
From the docs:
set_permissions [-p vhostpath] {user} {conf} {write} {read}
So something similar to this will give your guest user unlimited access:
rabbitmqctl set_permissions -p /myvhost guest ".*" ".*" ".*"
| RabbitMQ | 17,054,533 | 21 |
I might be misunderstanding how this works (which is why I'm asking), but I think when a celery worker consumes a task from RabbitMQ it puts a lock on it -- so to speak -- and then must acknowledge it completed that task onces it's done. So say I have 4 workers which all have the prefetch setting at 1 and queue of 6 ta... | This is mentioned in the FAQ, but I can't blame you for not finding it:
http://docs.celeryproject.org/en/latest/faq.html#should-i-use-retry-or-acks-late
The default behavior of early ack is there because we don't want to enforce users
to write idempotent tasks.
| RabbitMQ | 12,594,802 | 21 |
I am using Celery with RabbitMQ. Lately, I have noticed that a large number of temporary queues are getting made.
So, I experimented and found that when a task fails (that is a tasks raises an Exception), then a temporary queue with a random name (like c76861943b0a4f3aaa6a99a6db06952c) is formed and the queue remains. ... | It sounds like you're using the amqp as the results backend. From the docs here are the pitfalls of using that particular setup:
Every new task creates a new queue on the server, with thousands of
tasks the broker may be overloaded with queues and this will affect
performance in negative ways. If you’re using Rab... | RabbitMQ | 7,144,025 | 21 |
I send the following message with content type application/json:
However whene i get messages from the same RabbitMQ Web console, it shows the payload as String.
What am I doing wrong? Or am I fundamentally misunderstanding and the Payload is always of type String?
| From the official docs:
AMQP messages also have a payload (the data that they carry), which AMQP brokers treat as an opaque byte array. The broker will not inspect or modify the payload. It is possible for messages to contain only attributes and no payload. It is common to use serialisation formats like JSON, Thrift, ... | RabbitMQ | 49,788,162 | 20 |
Is it possible to use a different message broker with celery?
For example: I would like to use PostgreSQL instead of RabbitMQ.
AFAIK it is only supported in the result backend: http://docs.celeryproject.org/en/latest/userguide/configuration.html#database-backend-settings
Since PostgreSQL 9.5 there is SKIP LOCKED which ... | Yes, you can use postgres as broker instead of rabbitmq. Here is a simple example to demonstrate it.
from celery import Celery
broker = 'sqla+postgresql://user:pass@host/dbname'
app = Celery(broker=broker)
@app.task
def add(x, y):
return x + y
Queuing tasks
In [1]: from demo import add
In [2]: add.delay(1,2... | RabbitMQ | 47,473,583 | 20 |
I have configured the RabbitMQ rabbitmq.config file with new port number i.e. 5671 with SSL.
Now I want to disable the default port i.e. 5672.
Config file as below :-
[
{rabbit, [
{ssl_listeners, [5671]},
{ssl_options, [{cacertfile,"/ay/app/xxx/softwares/rabbitmq_server-3.1.1/etc/ssl/cacert.pem"},
... | To disable standart RabbitMQ 5672 port add {tcp_listeners, []} to your rabbitmq.conf:
[
{rabbit, [
{tcp_listeners, []},
{ssl_listeners, [5671]},
{ssl_options, [{cacertfile,"/ay/app/xxx/softwares/rabbitmq_server-3.1.1/etc/ssl/cacert.pem"},
{certfile,"/ay/app/xxx/softwares/rabbitmq_se... | RabbitMQ | 19,806,313 | 20 |
When I route a task to a particular queue it works:
task.apply_async(queue='beetroot')
But if I create a chain:
chain = task | task
And then I write
chain.apply_async(queue='beetroot')
It seems to ignore the queue keyword and assigns to the default 'celery' queue.
It would be nice if celery supported routing in chai... | I do it like this:
subtask = task.s(*myargs, **mykwargs).set(queue=myqueue)
mychain = celery.chain(subtask, subtask2, ...)
mychain.apply_async()
| RabbitMQ | 14,953,521 | 20 |
I am using celery with a rabbitmq backend. It is producing thousands of queues with 0 or 1 items in them in rabbitmq like this:
$ sudo rabbitmqctl list_queues
Listing queues ...
c2e9b4beefc7468ea7c9005009a57e1d 1
1162a89dd72840b19fbe9151c63a4eaa 0
07638a97896744a190f8131c3ba063de 0
b34f8d6d7402408c... | Celery with the AMQP backend will store task tombstones (results) in an AMQP queue named with the task ID that produced the result. These queues will persist even after the results are drained.
A couple recommendations:
Apply ignore_result=True to every task you can. Don't depend on results from other tasks.
Switch ... | RabbitMQ | 14,636,534 | 20 |
I have tried to use Rabbitmq server for some reason the connection closes abruptly even though I passed the correct username and password.
Rabbitmq server is running on port 5672 and telneting to my server at port 5672 says its running fine.
I have installed rabbitmq server in CentOS and my rabbitmq server log are as ... | connection_closed_abruptly means the client closed the TCP connection without going through the proper AMQP connection termination process.
Is your rabbit server behind a load balancer? A common cause for connections being abruptly closed as soon as they're started is a TCP load balancer's heartbeat. If this is the cas... | RabbitMQ | 13,946,153 | 20 |
When using RabbitMQ for sending messages you basically have exchanges, queues and bindings. I've understood their idea and how they relate to each other, but I am not quite sure who sets up what.
Basically, I have three scenarios in my application.
Scenario 1: One publisher, several worker processes
What I want to achi... | I think what you say is right except on Scenario 3.
If messages should not be lost if a consumer goes offline then you need durable queues and the queues can't be auto_delete'd.
Everything else seems right to me.
In the case of scenario 2 you could also let RabbitMQ auto-generate queue names for you and then let those... | RabbitMQ | 12,597,006 | 20 |
I'm just looking in to the config details of RabbitMQ and came across
[{rabbit, [{vm_memory_high_watermark, 0},
{disk_free_limit, {mem_relative, 1.0}}
]
}]
What does this config mean?
vm_memory_high_watermark set to 0 means => Block all publishers immediately the rabbitmq app starts? But we still... | The vm_memory_high_watermark is a percentage value is related to memory flow control in RabbitMQ.
If you take a look at Memory flow control you will see that it says, under "Memory-Based Flow Control" heading:
The RabbitMQ server detects the total amount of RAM installed in the computer on startup and when rabbitmqctl... | RabbitMQ | 12,175,156 | 20 |
I'm trying to install the RabbitMQ PECL extension but after running
sudo pecl install amqp
I get the following cryptic error message, which extensive googling hasn't helped resolve.
I have these packages installed:
librabbitmq - RabbitMQ C client itself)
librabbitmq-dev - dev headers etc.
and RabbitMQ runnin... | I had to install it applying following steps found here:
# Download the rabbitmq-c library @ version 0-9-1
git clone git://github.com/alanxz/rabbitmq-c.git
cd rabbitmq-c
# Enable and update the codegen git submodule
git submodule init
git submodule update
# Configure, compile and install
autoreconf -i && ./conf... | RabbitMQ | 9,520,914 | 20 |
I have a RabbitMQ cluster with two nodes in production and the cluster is breaking with these error messages:
=ERROR REPORT==== 23-Dec-2011::04:21:34 ===
** Node rabbit@rabbitmq02 not responding **
** Removing (timedout) connection **
=INFO REPORT==== 23-Dec-2011::04:21:35 ===
node rabbit@rabbitmq02 lost 'rabbit'
=ER... | RabbitMQ Clusters do not work well on unreliable networks (part of RabbitMQ documentation). So when the network failure happens (in a two node cluster) each node thinks that it is the master and the only node in the cluster. Two master nodes don't automatically reconnect, because their states are not automatically sync... | RabbitMQ | 8,654,053 | 20 |
I am new to Spring AMQP. I am having an application which is a producer sending messages to the other application which is a consumer.
Once the consumer receives the message, we will do validation of the data.
If the data is proper we have to ACK and message should be removed from the Queue.
If the data is improper we... | See the documentation.
By default, (with defaultRequeueRejected=true) the container will ack the message (causing it to be removed) if the listener exits normally or reject (and requeue) it if the listener throws an exception.
If the listener (or error handler) throws an AmqpRejectAndDontRequeueException, the default b... | RabbitMQ | 39,530,787 | 19 |
I have a Spring AMQP message listener running.
public class ConsumerService implements MessageListener {
@Autowired
RabbitTemplate rabbitTemplate;
@Override
public void onMessage(Message message) {
try {
testService.process(message); //This process method can throw Business Excepti... | Since onMessage() doesn't allow to throw checked exceptions you can wrap the exception in a RuntimeException and re-throw it.
try {
testService.process(message);
} catch (BusinessException e) {
throw new RuntimeException(e);
}
Note however that this may result in the message to be re-delivered indefinitely. He... | RabbitMQ | 36,979,840 | 19 |
I have a RabbitMQ 3.4.2 instance with a web management plugin installed.
When I push to the message {'operationId': 194} to the queue using Python's kombu queue package, the message is read on the other end as a dictionary.
However, when I send the message using the web console:
I get the following error on the receiv... | I had to use content_type instead of content-type (an underscore instead of a hyphen).
This is a pretty questionable design decision, because the standard everybody knows is content-type.
| RabbitMQ | 34,200,756 | 19 |
I need to limit the rate of consuming messages from rabbitmq queue.
I have found many suggestions, but most of them offer to use prefetch option. But this option doesn't do what I need. Even if I set prefetch to 1 the rate is about 6000 messages/sec. This is too many for consumer.
I need to limit for example about 70 t... | Implementing a token bucket might help:
https://en.wikipedia.org/wiki/Token_bucket
You can write a producer that produces to the "token bucket queue" at a fixed rate with a TTL on the message (maybe expires after a second?) or just set a maximum queue size equal to your rate per second. Consumers that receive a "normal... | RabbitMQ | 29,226,590 | 19 |
I've been learning RabbitMQ various topologies, however, I couldn't find any reference to dynamic queue creation (aka Declare Queue) emitted from a producer.
The idea would be to create queues dynamically depending on a particular event (e.g a HTTP request). The queue would be temporary with a TTL set and named after t... | Essentially, what you want to do is use RabbitMQ to buffer messages waiting in a set of queues (which is what a message queuing system does by definition). :)
Assuming you know what your queues are from the consuming side, you won't have any issues. There is no constraint that a producer can't create a queue. As a cav... | RabbitMQ | 21,265,242 | 19 |
I have create a simple publisher and a consumer which subscribes on the queue using basic.consume.
My consumer acknowledges the messages when the job runs without an exception. Whenever I run into an exception I don´t ack the message and return early. Only the acknowledged messages disappear from the queue, so that´s ... | If message was not acknowledged and application fails, it will be redelivered automatically and redelivered property on envelope will be set to true (unless you consume them with no-ack = true flag).
UPD:
You have to nack message with redelivery flag in your catch block
try {
//Do some business logic
} ... | RabbitMQ | 17,654,475 | 19 |
How can I use two different celery project which consumes messages from single RabbitMQ installation.
Generally, these scripts work fine if I use different rabbitmq for them. But on production machine, I need to share the same RabbitMQ backend for them.
Note: Due to some constraint, I cannot merge new projects in exist... | RabbitMQ has the ability to create virtual message brokers called virtual
hosts or vhosts. Each one is essentially a mini-RabbitMQ server with its own queues. This lets you safely use one RabbitMQ server for multiple applications.
rabbitmqctl add_vhost command creates a vhost.
By default Celery uses the / default vhost... | RabbitMQ | 12,209,652 | 19 |
I just switched from ForkPool to gevent with concurrency (5) as the pool method for Celery workers running in Kubernetes pods. After the switch I've been getting a non recoverable erro in the worker:
amqp.exceptions.PreconditionFailed: (0, 0): (406) PRECONDITION_FAILED - delivery acknowledgement on channel 1 timed out.... | The accepted answer is the correct answer. However, if you have an existing RabbitMQ server running and do not want to restart it, you can dynamically set the configuration value by running the following command on the RabbitMQ server:
rabbitmqctl eval 'application:set_env(rabbit, consumer_timeout, 36000000).'
This wil... | RabbitMQ | 69,828,547 | 18 |
I have a .net micro-service receiving messages using RabbitMQ client, I need to test the following:
1- consumer is successfully connected to rabbitMq host.
2- consumer is listening to queue.
3- consumer is receiving messages successfully.
To achieve the above, I have created a sample application that sends messages and... | I have built many such tests. I have thrown up some basic code on
GitHub here with .NET Core 2.0.
You will need a RabbitMQ cluster for these automated tests. Each test starts by eliminating the queue to ensure that no messages already exist. Pre existing messages from another test will break the current test.
I have a ... | RabbitMQ | 50,176,793 | 18 |
I am trying to build my airflow using docker and rabbitMQ. I am using rabbitmq:3-management image. And I am able to access rabbitMQ UI, and API.
In airflow I am building airflow webserver, airflow scheduler, airflow worker and airflow flower. Airflow.cfg file is used to config airflow.
Where I am using broker_url = amq... | From within your airflow containers, you should be able to connect to the service rabbit1. So all you need to do is to change amqp://user:**@localhost:5672//: to amqp://user:**@rabbit1:5672//: and it should work.
Docker compose creates a default network and attaches services that do not explicitly define a network to i... | RabbitMQ | 44,710,248 | 18 |
I'm working on a personnal project which is to transform a monolithic web application into microservices (each service has its own database).
At this moment the monolithic backend is made with NodeJS and is able to reply REST request.
When I began to split the application into multiple services I faced the next probl... | Tom suggested a pretty good link, where the top-voted answer with its reasoning and solution is the one you can rely on. Your specific problem may be rooted in the fact that Register Service and User Service are separate. Maybe they should not be?
Ideally, Register service should publish "UserRegistered" event to a bu... | RabbitMQ | 41,636,566 | 18 |
We have a wrapper library around RabbitMQ at my workplace, created by someone who no longer works here. I'm designing a new system using Rabbit, and am working out the best approach for declaring queues, exchanges and bindings. Our Rabbit architecture has a few federated global zones, and each zone has multiple Rabbit ... |
Is re-declaring the queues and exchanges a significant performance hit
it can be for a very large volume of messages
Is re-declaring on each use a good approach because it handles queues/exchanges disappearing due to broker restarts or explicit deletion?
"good approach" - no.
"effective" at preventing disappeared e... | RabbitMQ | 35,445,391 | 18 |
RabbitMQ allows you to "heartbeat" a connection, i.e. from time to time the client and the server check (using empty messages) that the other party is still there and available. So far, so good.
Unfortunately, I was not able to find a place in the documentation where a suggestion is made what a reasonable value for thi... | This answer if for RabbitMQ < 3.5.5, for newer versions see the answer from @bmaupin.
It depends on your application needs. Out of the box it is 10 min for RabbitMQ. If you fail to ack heartbeat twice (20min of inactivity), connection will be closed immediately without sending any connection.close method or any error f... | RabbitMQ | 25,984,602 | 18 |
Ok here is an overview of what's going on:
M <-- Message with unique id of 1234
|
+-Start Queue
|
|
| <-- Exchange
/|\
/ | \
/ | \ <-- bind to multiple queues
Q1 Q2 Q3
\ | / <-- start of the problem is here
\ | /
\ | /
\|/
|
Q4 <-- Queues 1,2 and 3 must finish firs... | You need to implement this: http://www.eaipatterns.com/Aggregator.html but the RabbitMQBundle for Symfony doesn't support that so you would have to use the underlying php-amqplib.
A normal consumer callback from the bundle will get an AMQPMessage. From there you can access the channel and manually publish to whatever e... | RabbitMQ | 13,861,459 | 18 |
I've got rabbitmq 2.8.2 set up with the web management interface running. The Queues and Exchanges show no data.
rabbitmqctl list_queues works and shows my queues.
I've done rabbitmqctl stop_app, start_app.. and also service rabbitmq-server restart.
Any idea how to get the queue & exchange details to populate?
| I had removed the guest user and created a new user for myself. My new user did not have permission to access the / vhost. Adding that permission fixed my issue.
| RabbitMQ | 10,939,545 | 18 |
This is probably a very simple answer, but I'm not seeing an obvious solution in the MassTransit docs or forums.
When you have some messages that have been moved over to the error queue in RabbitMQ, what's the best mechanism for getting them back into the processing queue? Also, is there any built-in logging of why the... | Enable logging with the right plugin (NLog, log4net, etc) and failures should be in the log, assuming the right log level is enabled.
There is no great way to move messages back. Dru has worked on a busdriver tool https://github.com/MassTransit/MassTransit/tree/master/src/Tools/BusDriver. This, I believe, will allow y... | RabbitMQ | 10,502,905 | 18 |
I know that we can do this to list queue in a rabbitmq:
rabbitmqctl list_queues
but how can I do this via pika?
| No.
Pika is an AMQP library.
If you want to manage an MQ Broker, then you need an MQ Broker management tool. Fortunately, RabbitMQ comes with such a tool if you install a recent version of RabbitMQ such as 2.7.1 and you install the RabbitMQ management plugins. That gives you a web GUI as well as a RESTful API that you ... | RabbitMQ | 9,652,295 | 18 |
Does RabbitMQ call the callback function for a consumer when it has some message for it, or does the consumer have to poll the RabbitMQ client?
So on the consumer side, if there is a PHP script, can RabbitMQ call it and pass the message/parameters to it. e.g. if rating is submitted on shard 1 and the aggregateRating ta... | The AMQPQueue::consume method is now a "proper" implementation of basic.consume as of version 1.0 of the PHP AMQP library (http://www.php.net/manual/en/amqpqueue.consume.php). Unfortunately, since PHP is a single threaded language, you cant do other things while waiting for a message in the same process space. If you c... | RabbitMQ | 9,151,698 | 18 |
Just upgraded to a new version of RabbitMQ -- 2.3.1 -- and now the following error occurs:
PRECONDITION_FAILED unknown delivery tag 1
...followed by the channel closing. This worked on an older RabbitMQ with no client-side changes.
In terms of application behavior:
When App A wants to send an async message to App b... | The only codepath that can cause that exception is through the broker handling a 'basic.ack', so this sounds like a client issue; check the client code.
In particular, check that you aren't ack'ing messages more than once. Doing so is in violation of the AMQP 0-9-1 spec:
A message MUST not be acknowledged more than o... | RabbitMQ | 5,075,694 | 18 |
I'm a little confused as to which one I should use. I think either will work, but is one better or more appropriate than the other?
http://github.com/ask/carrot/tree/master
http://github.com/ask/celery/tree/master
| If you need to send/receive messages to/from AMQP message queues, use carrot.
If you want to run scheduled tasks on a number of machines, use celery.
If you're making soup, use both ;-)
| RabbitMQ | 1,102,254 | 18 |
I want to set message header while sending a message to rabbit.
I am using below code, but confused how to set message header in it.
public static <T> void sendMessage(String routingKey,final Object message,Class<T> type){
DefaultClassMapper typeMapper = new DefaultClassMapper();
typeMapper.setDefaultType(typ... | Java 8:
template.convertAndSend(routingKey, message, m -> {
m.getMessageProperties().getHeaders().put("foo", "bar");
m.getMessageProperties().setPriority(priority);
return m;
});
Java 6,7:
template.convertAndSend(routingKey, message, new MessagePostProcessor() {
@Override
public Message po... | RabbitMQ | 39,853,393 | 17 |
I have two, separate RabbitMQ instances. I'm trying to find the best way to listen to events from both.
For example, I can consume events on one with the following:
credentials = pika.PlainCredentials(user, pass)
connection = pika.BlockingConnection(pika.ConnectionParameters(host="host1", credentials=credentials))
cha... | The answer to "what is the best way" depends heavily on your usage pattern of queues and what you mean by "best". Since I can't comment on questions yet, I'll just try to suggest some possible solutions.
In each example I'm going to assume exchange is already declared.
Threads
You can consume messages from two queues o... | RabbitMQ | 28,550,140 | 17 |
I have a set up to send messages to durable queues from server (NodeJS) and the client (android app) listens to messages on their respective queues (each android device listens to its corresponding queue which is unique).
As per the RabbitMQ document, when we try to connect to a queue with empty name (i.e "") then Rabb... | If you are creating queue with blank name a random queue name amq.gen-* will be generated.
If you are connecting to queue with blank name then, depending of method, last declared on this channel queue name will be used. If no queue was declared or method doesn't support blank queue name error will be thrown.
See queue.... | RabbitMQ | 22,194,675 | 17 |
It seems PostgreSQL does not allow to create a database table named 'user'. But MySQL will allow to create such a table.
Is that because it is a key word? But Hibernate cannot identify any issue (even if we set the PostgreSQLDialect).
| user is a reserved word and it's usually not a good idea use reserved words for identifiers (tables, columns).
If you insist on doing that you have to put the table name in double quotes:
create table "user" (...);
But then you always need to use double quotes when referencing the table. Additionally the table name is... | PostgreSQL | 22,256,124 | 157 |
I've just got myself a little bit stuck with some SQL. I don't think I can phrase the question brilliantly - so let me show you.
I have two tables, one called person, one called appointment. I'm trying to return the number of appointments a person has (including if they have zero). Appointment contains the person_id an... | You want an outer join for this (and you need to use person as the "driving" table)
SELECT person.person_id, COUNT(appointment.person_id) AS "number_of_appointments"
FROM person
LEFT JOIN appointment ON person.person_id = appointment.person_id
GROUP BY person.person_id;
The reason why this is working, is that the o... | PostgreSQL | 14,793,057 | 157 |
Ok I have a table with a indexed key and a non indexed field.
I need to find all records with a certain value and return the row.
I would like to know if I can order by multiple values.
Example:
id x_field
-- -----
123 a
124 a
125 a
126 b
127 f
128 b
129 a
130 x
131 x
132 b
133 ... | ...
WHERE
x_field IN ('f', 'p', 'i', 'a') ...
ORDER BY
CASE x_field
WHEN 'f' THEN 1
WHEN 'p' THEN 2
WHEN 'i' THEN 3
WHEN 'a' THEN 4
ELSE 5 -- fallback for values not inside the IN clause. eg : x_field = 'b'
END, id
| PostgreSQL | 6,332,043 | 157 |
How do you view a stored function or procedure?
Say I have an old function without the original definition - I want to see what it is doing in pg/psql but I can't seem to figure out a way to do that.
using Postgres version 8.4.1
| \df+ <function_name> in psql.
| PostgreSQL | 3,524,859 | 157 |
I am running my development on Ubuntu 11.10, and RubyMine
Here is my development settings for the database.yml: which RubyMine created for me
development:
adapter: postgresql
encoding: unicode
database: mydb_development
pool: 5
username: myuser
password:
when I try to run the app, I get this error below, i... | If you installed postresql on your server then just host: localhost to database.yml, I usually throw it in around where it says pool: 5. Otherwise if it's not localhost definitely tell that app where to find its database.
development:
adapter: postgresql
encoding: unicode
database: kickrstack_development
host:... | PostgreSQL | 9,987,171 | 155 |
myCol
------
true
true
true
false
false
null
In the above table, if I do :
select count(*), count(myCol);
I get 6, 5
I get 5 as it doesn't count the null entry.
How do I also count the number of true values (3 in the example)?
(This is a simplification and I'm actually using a much more complicated expression w... | SELECT COALESCE(sum(CASE WHEN myCol THEN 1 ELSE 0 END),0) FROM <table name>
or, as you found out for yourself:
SELECT count(CASE WHEN myCol THEN 1 END) FROM <table name>
| PostgreSQL | 5,396,498 | 155 |
I would like to list all tables in the liferay database in my PostgreSQL install. How do I do that?
I would like to execute SELECT * FROM applications; in the liferay database. applications is a table in my liferay db. How is this done?
Here's a list of all my databases:
postgres=# \list
... | If you wish to list all tables, you must use:
\dt *.*
to indicate that you want all tables in all schemas. This will include tables in pg_catalog, the system tables, and those in information_schema. There's no built-in way to say "all tables in all user-defined schemas"; you can, however, set your search_path to a lis... | PostgreSQL | 12,445,608 | 154 |
I have a two tables
Student
--------
Id Name
1 John
2 David
3 Will
Grade
---------
Student_id Mark
1 A
2 B
2 B+
3 C
3 A
Is it possible to make native Postgresql SELECT to get results like below:
Name Array of marks
-----------------------
'John', {'... | Use array_agg: http://www.sqlfiddle.com/#!1/5099e/1
SELECT s.name, array_agg(g.Mark) as marks
FROM student s
LEFT JOIN Grade g ON g.Student_id = s.Id
GROUP BY s.Id
By the way, if you are using Postgres 9.1, you don't need to repeat the columns on SELECT to GROUP BY, e.g. you don't need to repeat the student n... | PostgreSQL | 10,928,210 | 154 |
If I have a docker-compose file like:
version: "3"
services:
postgres:
image: postgres:9.4
volumes:
- db-data:/var/lib/db
volumes:
db-data:
... then doing docker-compose up creates a named volume for db-data. Is there a way to remove this volume via docker-compose? If it were an anonymous volume, the... | docker-compose down -v
removes all volumes attached. See the docs
| PostgreSQL | 45,511,956 | 153 |
I'm looking to write a postgresql query to do the following :
if(field1 > 0, field2 / field1 , 0)
I've tried this query, but it's not working
if (field1 > 0)
then return field2 / field1 as field3
else return 0 as field3
thank youu
| As stated in PostgreSQL docs here:
The SQL CASE expression is a generic conditional expression, similar to if/else statements in other programming languages.
Code snippet specifically answering your question:
SELECT field1, field2,
CASE
WHEN field1>0 THEN field2/field1
ELSE 0
END
AS field3
FROM test
| PostgreSQL | 19,029,842 | 153 |
I have a small table (~30 rows) in my Postgres 9.0 database with an integer ID field (the primary key) which currently contains unique sequential integers starting at 1, but which was not created using the 'serial' keyword.
How can I alter this table such that from now on inserts to this table will cause this field to ... | Look at the following commands (especially the commented block).
DROP TABLE foo;
DROP TABLE bar;
CREATE TABLE foo (a int, b text);
CREATE TABLE bar (a serial, b text);
INSERT INTO foo (a, b) SELECT i, 'foo ' || i::text FROM generate_series(1, 5) i;
INSERT INTO bar (b) SELECT 'bar ' || i::text FROM generate_series(1, ... | PostgreSQL | 9,490,014 | 153 |
Does Postgres have any way to say ALTER TABLE foo ADD CONSTRAINT bar ... which will just ignore the command if the constraint already exists, so that it doesn't raise an error?
| A possible solution is to simply use DROP IF EXISTS before creating the new constraint.
ALTER TABLE foo DROP CONSTRAINT IF EXISTS bar;
ALTER TABLE foo ADD CONSTRAINT bar ...;
Seems easier than trying to query information_schema or catalogs, but might be slow on huge tables since it always recreates the constraint.
Edi... | PostgreSQL | 6,801,919 | 153 |
We use copy command to copy data of one table to a file outside database.
Is it possible to copy data of one table to another table using command.
If yes can anyone please share the query.
Or is there any better approach like we can use pg_dump or something like that.
| You cannot easily do that, but there's also no need to do so.
CREATE TABLE mycopy AS
SELECT * FROM mytable;
or
CREATE TABLE mycopy (LIKE mytable INCLUDING ALL);
INSERT INTO mycopy
SELECT * FROM mytable;
If you need to select only some columns or reorder them, you can do this:
INSERT INTO mycopy(colA, colB)
SELECT co... | PostgreSQL | 31,284,514 | 152 |
I have this query I have written in PostgreSQL that returns an error saying:
[Err] ERROR:
LINE 3: FROM (SELECT DISTINCT (identifiant) AS made_only_recharge
This is the whole query:
SELECT COUNT (made_only_recharge) AS made_only_recharge
FROM (
SELECT DISTINCT (identifiant) AS made_only_recharge
FROM cdr_dat... | Add an ALIAS onto the subquery,
SELECT COUNT(made_only_recharge) AS made_only_recharge
FROM
(
SELECT DISTINCT (identifiant) AS made_only_recharge
FROM cdr_data
WHERE CALLEDNUMBER = '0130'
EXCEPT
SELECT DISTINCT (identifiant) AS made_only_recharge
FROM cdr_data
... | PostgreSQL | 14,767,209 | 152 |
I have a query like this that nicely generates a series of dates between 2 given dates:
select date '2004-03-07' + j - i as AllDate
from generate_series(0, extract(doy from date '2004-03-07')::int - 1) as i,
generate_series(0, extract(doy from date '2004-08-16')::int - 1) as j
It generates 162 dates between 2004... | Can be done without conversion to/from int (but to/from timestamp instead)
SELECT date_trunc('day', dd):: date
FROM generate_series
( '2007-02-01'::timestamp
, '2008-04-01'::timestamp
, '1 day'::interval) dd
;
| PostgreSQL | 14,113,469 | 152 |
I would like to take a look at the PostgreSQL log files to see what my app writes to them but I can't find them.
Any ideas?
| On OSX Homebrew installation the log can be found at:
Latest Homebrew:
/opt/homebrew/var/log/postgres.log
or older:
/usr/local/var/log/postgres.log
or for older version of postgres (< 9.6)
/usr/local/var/postgres/server.log
Bonus - check if PostgreSQL is running using Homebrew:
brew services info --all
| PostgreSQL | 2,563,494 | 152 |
I am working with a fresh postgresql install, with 'postgres' super user. Logged in via:
sudo -u postgres psql
postgres=# createdb database
postgres-# \list
List of databases
Name | Owner | Encoding | Collation | Ctype | Access privileges
-----------+----------+... | createdb is a command line utility which you can run from bash and not from psql.
To create a database from psql, use the create database statement like so:
create database [databasename];
Note: be sure to always end your SQL statements with ;
| PostgreSQL | 13,321,005 | 151 |
I have a json array stored in my postgres database.
The json looks like this:
[
{
"operation": "U",
"taxCode": "1000",
"description": "iva description",
"tax": "12"
},
{
"operation": "U",
"taxCode": "1001",
"description": "iva description",
"ta... | I post the answer originally written by pozs in the comment section.
unnest() is for PostgreSQL's array types.
Instead one of the following function can be used:
json_array_elements(json) (9.3+)
jsonb_array_elements(jsonb) (9.4+)
json[b]_array_elements_text(json[b]) (9.4+)
Example:
select * from json_array_elements... | PostgreSQL | 36,174,881 | 150 |
I would like to delete rows which contain a foreign key, but when I try something like this:
DELETE FROM osoby WHERE id_osoby='1'
I get this statement:
ERROR: update or delete on table "osoby" violates foreign key constraint "kontakty_ibfk_1" on table "kontakty"
DETAIL: Key (id_osoby)=(1) is still referenced from... | To automate this, you could define the foreign key constraint with ON DELETE CASCADE.
I quote the the manual for foreign key constraints:
CASCADE specifies that when a referenced row is deleted, row(s)
referencing it should be automatically deleted as well.
Look up the current FK definition like this:
SELECT pg_get_c... | PostgreSQL | 14,182,079 | 150 |
I'm trying to do something like this in postgres:
UPDATE table1 SET (col1, col2) = (SELECT col2, col3 FROM othertable WHERE othertable.col1 = 123);
INSERT INTO table1 (col1, col2) VALUES (SELECT col1, col2 FROM othertable)
But point 1 is not possible even with postgres 9.0 as mentioned in the docs (http://www.postgre... | For the UPDATE
Use:
UPDATE table1
SET col1 = othertable.col2,
col2 = othertable.col3
FROM othertable
WHERE othertable.col1 = 123;
For the INSERT
Use:
INSERT INTO table1 (col1, col2)
SELECT col1, col2
FROM othertable
You don't need the VALUES syntax if you are using a SELECT to populate the INSERT ... | PostgreSQL | 3,736,732 | 150 |
I cannot understand the syntax error in creating a composite key. It may be a logic error, because I have tested many varieties.
How do you create composite keys in Postgres?
CREATE TABLE tags
(
(question_id, tag_id) NOT NULL,
question_id INTEGER NOT NULL,
tag_id SERIAL NO... | Your compound PRIMARY KEY specification already does what you want. Omit the line that's giving you a syntax error, and omit the redundant CONSTRAINT (already implied), too:
CREATE TABLE tags
(
question_id INTEGER NOT NULL,
tag_id SERIAL NOT NULL,
tag1 VARCHAR(20),
... | PostgreSQL | 1,285,967 | 150 |
I have just install Postgres 9.3 on Windows 7. The installation completed successfully. It has never asked me to provide the password for postgres user.
The service postgresql-x64-9.3 is up and running. However, I cannot connect: I do not not know the password. I've found the following answer, but it did not help:
simi... | [WINDOWS]
https://stackoverflow.com/a/27108276/1087499
[LINUX]
might work for windows too
After installing postgres follow following steps in order to setup password for default system account of Linux execute following in terminal:
user:~$ sudo -i -u postgres
postgres@user:~$ psql
after executing above two commands y... | PostgreSQL | 27,107,557 | 149 |
I'd like to perform division in a SELECT clause. When I join some tables and use aggregate function I often have either null or zero values as the dividers. As for now I only come up with this method of avoiding the division by zero and null values.
(CASE(COALESCE(COUNT(column_name),1)) WHEN 0 THEN 1
ELSE (COALESCE(CO... | You can use NULLIF function e.g.
something/NULLIF(column_name,0)
If the value of column_name is 0 - result of entire expression will be NULL
| PostgreSQL | 17,681,375 | 149 |
How can I add comment to column in PostgreSQL?
create table session_log (
UserId int index not null,
PhoneNumber int index);
| Comments are attached to a column using the comment statement:
create table session_log
(
userid int not null,
phonenumber int
);
comment on column session_log.userid is 'The user ID';
comment on column session_log.phonenumber is 'The phone number including the area code';
You can also add a comment to the ... | PostgreSQL | 32,070,876 | 148 |
MySQL's explain output is pretty straightforward. PostgreSQL's is a little more complicated. I haven't been able to find a good resource that explains it either.
Can you describe what exactly explain is saying or at least point me in the direction of a good resource?
| The part I always found confusing is the startup cost vs total cost. I Google this every time I forget about it, which brings me back to here, which doesn't explain the difference, which is why I'm writing this answer. This is what I have gleaned from the Postgres EXPLAIN documentation, explained as I understand it.
H... | PostgreSQL | 117,262 | 148 |
Before anything, please note that I have found several similar questions on Stack Overflow and articles all over the web, but none of those helped me fix my issue:
PG Error could not connect to server: Connection refused Is the server running on port 5432?
PG::ConnectionBad - could not connect to server: Connection re... | run postgres -D /usr/local/var/postgres and you should see something like:
FATAL: lock file "postmaster.pid" already exists
HINT: Is another postmaster (PID 379) running in data directory "/usr/local/var/postgres"?
Then run kill -9 PID in HINT
And you should be good to go.
| PostgreSQL | 37,307,346 | 147 |
I have a query that returns avg(price)
select avg(price)
from(
select *, cume_dist() OVER (ORDER BY price desc) from web_price_scan
where listing_Type='AARM'
and u_kbalikepartnumbers_id = 1000307
and (EXTRACT(Day FROM (Now()-dateEnded)))*24 < 48
and price>( select avg(price)* 0.5... | use coalesce
COALESCE(value [, ...])
The COALESCE function returns the first of its arguments that is not null.
Null is returned only if all arguments are null. It is often
used to substitute a default value for null values when data is
retrieved for display.
Edit
Here's an example of COALESCE with your query:
SE... | PostgreSQL | 11,007,009 | 147 |
I need to remove some attributes from a json type column.
The Table:
CREATE TABLE my_table( id VARCHAR(80), data json);
INSERT INTO my_table (id, data) VALUES (
'A',
'{"attrA":1,"attrB":true,"attrC":["a", "b", "c"]}'
);
Now, I need to remove attrB from column data.
Something like alter table my_table drop column ... | Update: for 9.5+, there are explicit operators you can use with jsonb (if you have a json typed column, you can use casts to apply a modification):
Deleting a key (or an index) from a JSON object (or, from an array) can be done with the - operator:
SELECT jsonb '{"a":1,"b":2}' - 'a', -- will yield jsonb '{"b":2}'
... | PostgreSQL | 23,490,965 | 146 |
I am looking for a way to implement the SQLServer-function datediff in PostgreSQL. That is, this function returns the count (as a signed integer value) of the specified datepart boundaries crossed between the specified start date and end date.
datediff(dd, '2010-04-01', '2012-03-05') = 704 // 704 changes of day in this... | Simply subtract them:
SELECT ('2015-01-12'::date - '2015-01-01'::date) AS days;
The result:
days
------
11
| PostgreSQL | 17,833,176 | 146 |
I have been migrating a MySQL db to Pg (9.1), and have been emulating MySQL ENUM data types by creating a new data type in Pg, and then using that as the column definition. My question -- could I, and would it be better to, use a CHECK CONSTRAINT instead? The MySQL ENUM types are implemented to enforce specific values ... | Based on the comments and answers here, and some rudimentary research, I have the following summary to offer for comments from the Postgres-erati. Will really appreciate your input.
There are three ways to restrict entries in a Postgres database table column. Consider a table to store "colors" where you want only 'red'... | PostgreSQL | 10,923,213 | 145 |
How can I tell if my Postgresql server is running or not?
I'm getting this message:
[~/dev/working/sw] sudo bundle exec rake db:migrate
rake aborted!
could not connect to server: Connection refused
Is the server running on host "localhost" and accepting
TCP/IP connections on port 5432?
Update:
> which postgre... | The simplest way to to check running processes:
ps auxwww | grep postgres
And look for a command that looks something like this (your version may not be 8.3):
/Library/PostgreSQL/8.3/bin/postgres -D /Library/PostgreSQL/8.3/data
To start the server, execute something like this:
/Library/PostgreSQL/8.3/bin/pg_ctl start... | PostgreSQL | 7,975,414 | 145 |
Is there a way with PostgreSQL to sort rows with NULL values in fields to the end of the selected table?
Like:
SELECT * FROM table ORDER BY somevalue, PUT_NULL_TO_END
| NULL values are sorted last in default ascending order. You don't have to do anything extra.
The issue applies to descending order, which is the perfect inverse and thus sorts NULL values on top.
PostgreSQL 8.3 introduced NULLS LAST:
ORDER BY somevalue DESC NULLS LAST
For PostgreSQL 8.2 and older or other RDBMS withou... | PostgreSQL | 7,621,205 | 145 |
This is a summary of what I am trying to do:
$array[0] = 1;
$array[1] = 2;
$sql = "SELECT * FROM table WHERE some_id = $array"
Obviously, there are some syntax issues, but this is what I want to do, and I haven't found anything yet that shows how to do it.
Currently, my plan is to do something along these lines:
fore... | SELECT *
FROM table
WHERE some_id = ANY(ARRAY[1, 2])
or ANSI-compatible:
SELECT *
FROM table
WHERE some_id IN (1, 2)
The ANY syntax is preferred because the array as a whole can be passed in a bound variable:
SELECT *
FROM table
WHERE some_id = ANY(?::INT[])
You would need to pass a string represen... | PostgreSQL | 10,738,446 | 143 |
I am using following query:
ALTER TABLE presales ALTER COLUMN code TYPE numeric(10,0);
to change the datatype of a column from character(20) to numeric(10,0) but I am getting the error:
column "code" cannot be cast to type numeric
| You can try using USING:
The optional USING clause specifies how to compute the new column value from the old; if omitted, the default conversion is the same as an assignment cast from old data type to new. A USING clause must be provided if there is no implicit or assignment cast from old to new type.
So this might ... | PostgreSQL | 7,683,359 | 143 |
I have a somewhat detailed query in a script that uses ? placeholders. I wanted to test this same query directly from the psql command line (outside the script). I want to avoid going in and replacing all the ? with actual values, instead I'd like to pass the arguments after the query.
Example:
SELECT *
FROM foo... | You can use the -v option e.g:
$ psql -v v1=12 -v v2="'Hello World'" -v v3="'2010-11-12'"
and then refer to the variables in SQL as :v1, :v2 etc:
select * from table_1 where id = :v1;
Please pay attention to how we pass string/date values using two quotes " '...' " But this way of interpolation is prone to SQL inject... | PostgreSQL | 7,389,416 | 143 |
Attempting to insert an escape character into a table results in a warning.
For example:
create table EscapeTest (text varchar(50));
insert into EscapeTest (text) values ('This is the first part \n And this is the second');
Produces the warning:
WARNING: nonstandard use of escape in a string literal
(Using PSQL 8.... | Partially. The text is inserted, but the warning is still generated.
I found a discussion that indicated the text needed to be preceded with 'E', as such:
insert into EscapeTest (text) values (E'This is the first part \n And this is the second');
This suppressed the warning, but the text was still not being returned c... | PostgreSQL | 935 | 143 |
I am trying to configure ssl certificate for PostgreSQL server. I have created a certificate file (server.crt) and key (server.key) in data directory and update the parameter SSL to "on" to enable secure connection.
I just want only the server to be authenticated with server certificates on the client side and don't re... | psql below 9.2 does not accept this URL-like syntax for options.
The use of SSL can be driven by the sslmode=value option on the command line or the PGSSLMODE environment variable, but the default being prefer, SSL connections will be tried first automatically without specifying anything.
Example with a conninfo stri... | PostgreSQL | 14,021,998 | 142 |
I have the following table projects.
id title created_at claim_window
1 Project One 2012-05-08 13:50:09.924 5
2 Project Two 2012-06-01 13:50:09.924 10
A) I want to find the deadline with the calculation deadline = created_at + claim_window, where claim_window is the number of days. Something... | This will give you the deadline :
select id,
title,
created_at + interval '1' day * claim_window as deadline
from projects
Alternatively the function make_interval can be used:
select id,
title,
created_at + make_interval(days => claim_window) as deadline
from projects
To get all proje... | PostgreSQL | 10,909,902 | 142 |
I am trying to create table with Postgis. I do it by this page. But when I import postgis.sql file, I get a lot of errors:
ERROR: type "geometry" does not exist
Does anybody know how can I fix it?
| I had the same problem, but it was fixed by running following code
CREATE EXTENSION postgis;
In detail,
open pgAdmin
select (click) your database
click "SQL" icon on the bar
run "CREATE EXTENSION postgis;" code
| PostgreSQL | 6,850,500 | 142 |
Did a new install of postgres 8.4 on mint ubuntu. How do I create a user for postgres and login using psql?
When I type psql, it just tells me
psql: FATAL: Ident authentication failed for user "my-ubuntu-username"
| There are two methods you can use. Both require creating a user and a database.
By default psql connects to the database with the same name as the user. So there is a convention to make that the "user's database". And there is no reason to break that convention if your user only needs one database. We'll be using mydat... | PostgreSQL | 2,172,569 | 142 |
When I have a column with separated values, I can use the unnest() function:
myTable
id | elements
---+------------
1 |ab,cd,efg,hi
2 |jk,lm,no,pq
3 |rstuv,wxyz
select id, unnest(string_to_array(elements, ',')) AS elem
from myTable
id | elem
---+-----
1 | ab
1 | cd
1 | efg
1 | hi
2 | jk
...
How can I include... | Postgres 14 or later
Use string_to_table() instead of unnest(string_to_array()) for a comma-separated string:
SELECT t.id, a.elem, a.nr
FROM tbl t
LEFT JOIN LATERAL string_to_table(t.elements, ',')
WITH ORDINALITY AS a(elem, nr) ON true;
fiddle
Related:
Split column into multiple rows in Postg... | PostgreSQL | 8,760,419 | 141 |
I'd like to make a random string for use in session verification using PostgreSQL. I know I can get a random number with SELECT random(), so I tried SELECT md5(random()), but that doesn't work. How can I do this?
| You can fix your initial attempt like this:
SELECT md5(random()::text);
Much simpler than some of the other suggestions. :-)
| PostgreSQL | 3,970,795 | 141 |
I have pgAdmin version 1.16.1 installed on my machine.
For exporting a table dump, I do:
Right click on the table => Choose backup => Set Format to Plain => Save the file as some_name.sql
Then I remove the table.
Ok, now I need to import the backup I just created from some_name.sql into the database.
How am I supposed ... |
In pgAdmin, select the required target schema in object tree (databases ->your_db_name -> schemas -> your_target_schema)
Click on Plugins/PSQL Console (in top-bar)
Write \i /path/to/yourfile.sql
Press enter
| PostgreSQL | 18,736,345 | 140 |
For development I'm using SQLite database with production in PostgreSQL. I updated my local database with data and need to transfer a specific table to the production database.
Running sqlite database .dump > /the/path/to/sqlite-dumpfile.sql, SQLite outputs a table dump in the following format:
BEGIN TRANSACTION;
CREAT... | You should be able to feed that dump file straight into psql:
/path/to/psql -d database -U username -W < /the/path/to/sqlite-dumpfile.sql
If you want the id column to "auto increment" then change its type from "int" to "serial" in the table creation line. PostgreSQL will then attach a sequence to that column so that I... | PostgreSQL | 4,581,727 | 140 |
I have an application using hibernate 3.1 and JPA annotations. It has a few objects with byte[] attributes (1k - 200k in size). It uses the JPA @Lob annotation, and hibernate 3.1 can read these just fine on all major databases -- it seems to hide the JDBC Blob vendor peculiarities (as it should do).
@Entity
public cl... |
What is the portable way to annotate a byte[] property?
It depends on what you want. JPA can persist a non annotated byte[]. From the JPA 2.0 spec:
11.1.6 Basic Annotation
The Basic annotation is the simplest
type of mapping to a database column.
The Basic annotation can be applied
to a persistent property or... | PostgreSQL | 3,677,380 | 140 |
Is it possible to change the constraint name in Postgres?
I have a PK added with:
ALTER TABLE contractor_contractor ADD CONSTRAINT commerce_contractor_pkey PRIMARY KEY(id);
And I want to to have different name for it, to be consistent with the rest of the system.
Shall I delete the existing PK constraint and create a ... | To rename an existing constraint in PostgreSQL 9.2 or newer, you can use ALTER TABLE:
ALTER TABLE name RENAME CONSTRAINT constraint_name TO new_constraint_name;
| PostgreSQL | 971,786 | 140 |
I am trying to do a like query like so
def self.search(search, page = 1 )
paginate :per_page => 5, :page => page,
:conditions => ["name LIKE '%?%' OR postal_code like '%?%'", search, search], order => 'name'
end
But when it is run something is adding quotes which causes the sql statement to come out like so
SE... | Your placeholder is replaced by a string and you're not handling it right.
Replace
"name LIKE '%?%' OR postal_code LIKE '%?%'", search, search
with
"name LIKE ? OR postal_code LIKE ?", "%#{search}%", "%#{search}%"
| PostgreSQL | 19,105,706 | 139 |
I'll need to invoke REFRESH MATERIALIZED VIEW on each change to the tables involved, right? I'm surprised to not find much discussion of this on the web.
How should I go about doing this?
I think the top half of the answer here is what I'm looking for: https://stackoverflow.com/a/23963969/168143
Are there any dangers t... |
I'll need to invoke REFRESH MATERIALIZED VIEW on each change to the tables involved, right?
Yes, PostgreSQL by itself will never call it automatically, you need to do it some way.
How should I go about doing this?
Many ways to achieve this. Before giving some examples, keep in mind that REFRESH MATERIALIZED VIEW co... | PostgreSQL | 29,437,650 | 138 |
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