PostgreSQL is an enterprise class, open-source, object-relational database management system (ORDBMS) available for all major platforms including Linux, UNIX, Windows and OS X. Please mention your exact PostgreSQL version when asking questions.

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Using dynamic column names in PostgreSQL

I am using PostgreSSQL 8.3. I want to execute this query: select COALESCE(col_fr,col,'Unknown') from my_table where id = 'abc'; Twist in the story is column name colum_fr should be generated ...
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Select records for a day and a day - 1 day

From one table, I want to get the records from one column position when the created_at = Today and when the created_at = created_at - 1.day COALESCE(array_agg(DISTINCT pr.position)) AS position, ...
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How to Configure PostgreSQL Hotstandby Automatic Failover

So I have configured two postgeSQL servers to have hotstand by streaming, now my question is, how can I configure it so that when the master server goes down, the slave server will become the new ...
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1answer
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What is the “last” data that get's backed up, when running pg_dump on a live server?

I'm wondering: If I start doing a pg_dump of a very large database (it would take hours), that is still running actively receiving writes, what is then the last data that goes into the backup? Is it: ...
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1answer
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log_min_duration_statement setting is ignored

I am running Postgresql 9.1 on Ubuntu. Exact Postgresql version is 9.1+129ubuntu1 as my package manager shows. I have 2 databases that are actively in use and they are used from a remote server. I ...
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2answers
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PostgreSQL, integer arrays, index for equality

I have a huge list of integer arrays (300,000,000 records) stored in Postgres 9.2 DB. I want to efficiently search these records for an exact match (equality only). I have heard of the intarray module ...
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1answer
183 views

What does “ERROR: failed to find parent tuple for heap-only tuple at (1192248,5) in table ”fruits“” mean?

After being bitten by the bug mentioned in the release notes of 9.3.4, I have realized that a very small part of my data is corrupt, after doing a failover. The bug showed it self as duplicate rows, ...
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Why is it not possible to alter a view with a “CREATE OR REPLACE”?

The Postgresql documentation is clear on this point: you can not change the columns of an existing view. The new query must generate the same columns that were generated by the existing view query ...
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Postgres Streaming Replication lagging, using lots of CPU and little I/O

We have 2 dedicated DB Servers. One is master and other is its streaming slave. Postgres version 9.0.17. We have similar hardware on both servers and using 15krpm SAS drive in Raid 10 for Database ...
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1answer
552 views

How to apply a patch in PostgreSQL on Windows?

How to apply a patch in PostgreSQL? I found an advice, but it seems to be suited for *NIX only. My PostgreSQL (9.3.1 EDIT: 9.3.4 now) was installed from an exe installer on Windows XP (32 bit), so I ...
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478 views

How do I validate all my constraints in postgresql?

It seems like I have been bitten by the first bug described in the release notes of postgresql 9.3.4: http://www.postgresql.org/docs/devel/static/release-9-3-4.html I now have e.g. duplicate primary ...
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Why does my table hold duplicate primary keys?

To my big (and worrying) surprise I just realized that my table with millions of rows, has a few handful of rows, where the primary key (ID) is a duplicate! I don't understand how this can ever ...
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1answer
2k views

Installing pgcrypto Extension

I have this password hash function that hashes a password to sha256. I've already got it running in pgadmin3 in a local database. I've done it by importing the extension, a feature that has been added ...
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Organizing a couple tables in postgresql

I have a data structure that is represented like this: { 'question_id': 1, 'is_required': False, 'question_text': [ { 'id': 1, ...
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2answers
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How to implement business logic permissions in PostgreSQL (or SQL in general)?

Let's assume I have a table of items: CREATE TABLE items ( item serial PRIMARY KEY, ... ); Now, I want to introduce the concept of "permissions" for each item (please note, I'm not talking ...
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2answers
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select specified number of unique IDs where second column is unique

Look at the following example starting from the top row (id=9) and work your way down, selecting a limit of 4 rows that have sec's that we have not yet seen. We "select" id=9 because we don't yet have ...
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1answer
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PostgreSQL 9.1: vacuumdb vs. autovacuum

Have a question on the difference between just allowing autovacuum to take care of vacuum'ing or having to run a full db vacuum in a certain interval (every night?, every week?). We used to run a ...
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Why does this query cause the Postgres worker process to consume so much memory?

I have a PostgreSQL 9.3.4 instance running in a CentOS 5.x VM (Linux 2.6.18-308.8.2.el5xen) with 6GB RAM. I've set shared_buffers to 1GB and work_mem to 1MB (a low value for testing). Here are my ...
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3answers
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Join table on some conditions

I've got a table called activities. And a table messages. Activity has many messages, and one message has one activity. This are the message columns : id sender_id receiver_id body activity_id I'm ...
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1answer
58 views

Consolidating large table

I need some help with a complex query. Table def: Table "public.agent_log" Column | Type | Modifiers ...
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2answers
4k views

Improve performance of COUNT/GROUP-BY in large PostgresSQL table?

I am running PostgresSQL 9.2 and have a 12 column relation with about 6,700,000 rows. It contains nodes in a 3D space, each one referencing a user (who created it). To query which user has created how ...
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2answers
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Problem translating MySQL to PostgreSQL

We're using Trac for issue tracking. I migrated it from MySQL to PostgreSQL, but some of the ticket queries no longer work. In the below, all I did this far is replace IFNULL() with COALESCE() and ...
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1answer
124 views

RETURN NEXT in Postgres Function

I'm currently writing a plpgsql function that will select from a table and produce a substantial amount of data. I was originally going to return an array, but I found a resource that explains the ...
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PostgreSQL: cache, disk, replication. What order?

I am thinking of using two servers in Master/Slave replication I want to add following condition: RAM size = dataset size * x, where x > 2. After that, I plan to force PGSQL to keep all data in RAM ...
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select and count based on a condition

I have two tables, proj: id name and proj_reports: id, position, created_at, key_id, proj_id and I want to select from key_reports for each proj_id: `- total number of `key_id` which can be done ...
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PostgreSQL Error: out of memory

I'm trying to run a query that should return around 2000 rows, but my RDS-hosted PostgreSQL 9.3 database is giving me the error "out of memory DETAIL: Failed on request of size 2048.". What does ...
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1answer
342 views

Postgres startup fail error

I was running some code when my laptop shut down. Now everytime I connect to the server, I get an error message as follows: ambangra@access1:~$ LOG: database system shutdown was interrupted; last ...
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2answers
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Privileges for database owner; application user

Quick version: What command should I issue to enable a database owner to allow it to access tables in this database and can this be done from that owner's account? Longer Version: I am creating ...
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1answer
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How can I speed up a Postgres query containing lots of Joins with an ILIKE condition

I have an odd problem which I really don't understand. Simply put I have a join containing 4 table joins, which I believe all have appropriate indexes, but which takes a ridiculous amount of time to ...
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1answer
771 views

Postgres memory usage too low

I have a 400GB Postgres 9.3.4 DB running on Fedora20, and a few indices per table. I have upped shared buffers to 4GB (the system has 16GB available), set shm in the kernel and set the ...
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1answer
44 views

Preparing a former master to run as slave again

I have a streaming replication setup using postgresql 9.3. I have two servers, the master (server_1) and the slave (server_2). The other day I did a failover to my slave (server_2). Now server_2 has ...
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How to index WHERE (start_date >= '2013-12-15')

I have a table named items, and inside the table there is a some_date column, with date as the datatype. I was wondering how can I index the some_date column with PostgreSQL SELECT "items".* FROM ...
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How to see all queries via pgBadger

The excellent pgBadger has an interface to reviewing specific queries - the slowest, by host, by user etc. Is it possible to see all queries processed, perhaps in a given timeframe. If not available ...
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What are the disadvantages of PostgreSQL compared to other DBMS? [closed]

I am a student studying PostgreSQL. I want to know the advantages and disadvantages of PostgreSQL in comparison to other DBMS.
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Reduce read write delays in specific database setup

I have a database with a large table with 15 columns (type double). It contains a large amount of data (~ 100 rows of data for every second. Holds 3 days of data). I also have a real-time program that ...
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Lost all my Postgres database tables? [closed]

I'm a novice using PostgreSQL on a local database that I created using Postgres.app on my Mac. My dbase included multiple related tables with ~50MB of data, and after restarting my Mac (system update) ...
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1answer
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PostgreSQL : send all rows of a table to a function

I have a table with one column (double precision numbers). I also have made a function (with double precision numbers as input and output), and I want to send every value of my table to the function, ...
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357 views

Howto debug sudden crazy high CPU usage

I'm running postgresql 9.3 on a production server. An hour ago, out of the "blue", I ran into an issue I have never encountered before: my server started to use CPU as crazy. The server is a standard ...
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1answer
355 views

Organizing Postgres Databases

Is there a way in pgAdmin to organize Postgres databases into "folders" or groups? Each Django project I'm creating has it's own Postgres database, and I would like to find a way to organize them. I ...
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6answers
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Efficiently storing irregular/repeating intervals (think calendar/events)

I am developing a service that relies on users being able to recieve messages that they themselves choose. These messages need to be stored somewhere before they are send for processing. Right now ...
3
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1answer
354 views

How to reuse an update trigger for multiple tables in postgresql?

In the database for a new project, I've started the convention of having each table have a last modified timestamp column. To implement this, I wrote a trigger for each table: CREATE TRIGGER ...
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581 views

Postgresql Database on external HD

I'm completely inexperienced with PostgreSQL, but have to do some work on it, and I have been googling for a solution for almost two days. I hope someone here can help me out. I have a PostgreSQL ...
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Granting permissions to PostgreSQL user

I am trying to grant permissions to one of my Postgres users. I am running CentOS with PostgreSQL, Ruby On Rails 3, ruby 1.9.3 postgres=# GRANT ALL PRIVILEGES ON loadmax TO loadmax; ERROR: relation ...
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Select Into Regexp_replace doesn't write changes into newly generated table

I have been using this query in postgres 9.1 in order to remove '' from existing data. Below is a sample of the data before running regexp_replace. 6'' 6'' 6'' 20'' 12'' 18'' 20'' 8'' 10'' '' '' ...
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Do I need to set tcpip_socket = true to allow remote connections to a postgresql database?

I am trying to enable remote connections to my postgresql 9.1 db running on ubuntu 12.04. This tutorial says to "set tcpip_socket to true" -- but it is for a centos server. I am on ubuntu. I ...
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Add 0 into array_agg if there is no matching data

I wrote this view, and it is selecting almost everything I want, but I do not get results for all: project_keywords(which has_many project_report(keyword_id, project_id)) So a project_keyword has a ...
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1answer
35 views

Suggested ways to route traffic between master / slave

I have multiple Postgres servers up, running in master / slave streaming replication mode. I was wondering what the suggested methods of routing write traffic to the master, and the read traffic to ...
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What happens in PostgreSQL checkpoint?

Here's part of my checkpoint log: 2014-03-26 11:51:29.341 CDT,,,18682,,532854fc.48fa,4985,,2014-03-18 09:15:24 CDT,,0,LOG,00000,"checkpoint complete: wrote 15047 buffers (1.4%); 0 transaction log ...
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database filesystem backup error

I get this error earch time: postgres=# select pg_stop_backup(); NOTICE: pg_stop_backup cleanup done, waiting for required WAL segments to be archived WARNING: pg_stop_backup still waiting for all ...
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2answers
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psql: id SERIAL PRIMARY KEY not starting with 1?

This is something I don't understand, can somebody explain? I create a table CREATE TABLE cali (id SERIAL PRIMARY KEY, ALK_from char, ALK_to char, AND_from char, AND_to char); Then ...