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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EC2 - How to correctly back up PostgreSQL data?

Here is the setup: 1 small Amazon Linux (EBS-backed) EC2 instance with 3 additional volumes. This is both a web server and database server. One volume for code, one for the PostgreSQL (8.4) data ...
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3answers
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Can a single PostgreSQL query use multiple cores?

In recent versions of PostgreSQL, can we share a query between two or more cores to get a performance boost? Or should we get faster cores?
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How do I detach all other users from a postgres database?

I need exclusive access to a database. Is it possible using an SQL command to "detach" all other users from a postgres database. Or maybe closing all other connections and then gaining exclusive ...
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4answers
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PostgreSQL user can not connect to server after changing password

I've met this with 4 roles I created: After changing password for a user in pgAdmin III using the GUI (1), that user can not log in any more. pgAdmin III show error message: An error has occurred: ...
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3answers
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How to drop all connections to a specific database in postgres without stopping the server?

I want to drop all connections (sessions) that are currently opened to a specific postgresql database but without restarting the server or disconnecting connections to other databases. How can I so ...
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Is it possible to quickly create/restore database snapshots with PostgreSQL?

First of all, I'm a developer, not a DBA or sysadmin; please be gentle :) I'm working on an application workflow where a single user action will trigger complex changes in the database - creating ...
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3answers
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Set names to attributes when creating JSON with row_to_json

Is it possible to rename default f1, f2, f3... names when using row_to_json function for only some columns? I can do row_to_json(customers) returning ...
13
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4answers
6k views

Locking issue with concurrent DELETE / INSERT in PostgreSQL

This is pretty simple, but I'm baffled by what PG does (v9.0). We start with a simple table: CREATE TABLE test (id INT PRIMARY KEY); and a few rows: INSERT INTO TEST VALUES (1); INSERT INTO TEST ...
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1answer
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How to migrate large blob table from mysql to postgresql?

I'm now in process of migrating my MySQL database to PostgreSQL. Almost everything went fine (well, after lots of googling for correct mysqldump params etc.) except one table I have - actually the ...
10
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1answer
2k views

Generate an exception with a Context

When PostgreSQL throws an exception, there is a line "CONTEXT" like: ERROR: INSERT has more target COLUMNS than expressions LINE 3: ... ...
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2answers
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Database for building a realtime analytics system

I want to build a system similar to Google Analytics (only used for internal use, less traffic and less feature), and mainly focus on Real time counting of unique URI visit/PV by different ...
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2answers
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PostgreSQL maximize performance SSD

I will have a huge PostgreSQL 9.3 database with many tables with more than 100M entries per table. This database will be basically be read-only (once I fill all the necessary tables and build the ...
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2answers
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PostgreSQL crash recovery

We are planning to use PostgreSQL in our application but are concerned about crash-safety and recovery. I can't find any database crash recovery method or process in PostgreSQL. I know there must be ...
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5answers
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What are the differences between “Stored Procedures” and “Stored Functions”?

So a comment from this question mentions, that there is a slight difference in "Stored Procedrues" and "Stored Funtions" in PostgreSQL. The comment links to a wikipedia article but some of this don't ...
12
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2answers
931 views

Modelling constraints on subset aggregates?

This is a cross-post from Stack Overflow. I figured I might get more interesting thoughts here. I am using PostgreSQL but I figure most of the top-end db's must have some similar capabilities, and ...
9
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1answer
7k views

PostgreSQL Database Data File Integrity Check

When running a PostgreSQL database system how do I know my database as a whole has 100% integrity? Basically how do I know if my data files and pages are all 100% good with no corruption? In the ...
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4answers
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No NULLs, yet invalid byte sequence for encoding “UTF8”: 0x00

I've spent the last 8 hours trying to import the output of 'mysqldump --compatible=postgresql' into PostgreSQL 8.4.9, and I've read at least 20 different threads here and elesewhere already about this ...
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4answers
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Why won't PostgreSQL 9.3 start on Ubuntu?

I have successfully installed PostgreSQL 9.3 from the APT repository on 2 VM's running Ubuntu 12.04 and 13.04...however, I cannot get it to install properly on my host machine running Ubuntu 12.04. ...
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1answer
794 views

How to access NEW or OLD field given only the field's name?

I'm writing a validation trigger. The trigger must validate that the sum of an array equals another field. Since I have many instances of this validation, I want to write a single procedure and create ...
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2answers
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How to choose a collation for international database?

I'm designing a database which will store data in different languages (using UTF-8), so I think the best way to display the queries results is ordering it according to the user's language during the ...
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2answers
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Possible to keep max number of records in postgresql?

Basically part of our Postgresql table is used to keep server access logs, and as such sometimes during production this can get pretty large. is there any way of setting in postgresql to have a ...
5
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1answer
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Ways to speed up IN queries under PostgreSQL

I have a query of the following form: SELECT * FROM twitter_personas WHERE twitter_user_id IN ($1, $2, $3, ..., $25000) The IN query has anywhere from 10 to 25000 values. The query runs for minutes ...
3
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1answer
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Cannot get my slave - replication server to start

My replication server will not start. I have followed the instructions here: http://opensourcedbms.com/dbms/setup-replication-with-postgres-9-2-on-centos-6redhat-el6fedora/ As well as several other ...
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2answers
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Creating High Availability Cluster with PostgreSQL

I am new to database design. I have a task to create a high-availability cluster. I Googled a lot, however I haven't found any good way to do this on PostgreSQL. Where should I start and what are ...
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2answers
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How to do incremental backup every hour in Postgres?

Trying to do an hourly incremental backup of a single Postgres server (Win7 64). I have the following setup in postgresql.conf: max_wal_senders = 2 wal_level = archive archive_mode = on ...
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3answers
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Indexes for SQL query with WHERE condition and GROUP BY

I am trying to determine which indexes to use for an SQL query with a WHERE condition and a GROUP BY which is currently running very slow. My query: SELECT group_id FROM counter WHERE ts between ...
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3answers
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Can IS DISTINCT FROM be combined with ANY or ALL somehow?

Is a postgres way of combining IS DISTINCT FROM with ANY or some other neat way of getting the same result? select count(*) from (select 'A' foo union all select 'Z' union all select null) z where ...
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2answers
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Streaming replication and failover on PostgreSQL

I am doing a proof of concept on PostgreSQL replication. After the discussion on forum we decided to go with streaming replication as the performance is good compared to other solutions. PostgreSQL is ...
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1answer
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Why would you index text_pattern_ops on a text column?

Today Seven Databases in Seven Weeks introduced me to per-operator indexes. You can index strings for pattern matching the previous queries by creating a text_pattern_ops operator class index, as ...
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3answers
544 views

What is retrieved from disk during a query?

Fairly simple question, probably answered somewhere, but I can't seem to form the right search question for Google... Do the number of columns in a particular table affect the performance of a query, ...
8
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1answer
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How to determine if there are [idle connections with] uncommitted transactions in PostgreSQL?

According to a comment on this question I asked about idle connections in PostgreSQL 9.2, some uncommitted transactions (possibly related to some of those idle connections) might cause some ...
7
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1answer
762 views

Equality query on NVARCHAR column yields multiple results in SQL Server 2012

I am in the process of moving a pet project from PostgreSQL (9.2.2) to SQL Server (2012 Standard). I've noticed an interesting phenomenon when querying unicode words. Given the definition: CREATE ...
7
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1answer
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Is the optimisation fence behaviour of a CTE (WITH query) specified in the SQL:2008 standard? If so, where?

I see frequent references to WITH queries (common table expressions, or CTEs) acting as an optimisation fence, where the server isn't permitted to push filters down into the CTE queries, pull common ...
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Compare two similar Postgres databases for differences

I occasionally download publicly available data sets in the form of Postgres dBs. These datasets are updated/modified/expanded over time by the repository host. Is there a Postgres command or ...
6
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1answer
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What are the privileges required to execute a trigger function in PostgreSQL 8.4?

What are the privileges required to execute a trigger function in PostgreSQL 8.4? It seems that the privileges set to a role does not matter to execute a trigger function. I think I have seen some ...
6
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1answer
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PostgreSQL: Unable to run repmgr cloned database

I'm running tests with PostgreSQL hot standby with 1 master, and exactly 1 slave. I am using the instructions on this guide: ...
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5answers
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PostgreSQL: The database cluster initialization failed

Both C:\PostgreSQL and C:\PostgreSQL\data have postgres user with full access and admin rights. I ran postgresql-9.1.2-1-windows.exe from postgres user as admin. Target C:\PostgreSQL Every way I ...
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2answers
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Running pg_dump on a hot standby server?

Disclaimer: I admittedly haven't tried this yet, but I'm not sure I would know if it wasn't working correctly, so I wanted to ask. I would like to run a nightly backup job (via pg_dumpall) from a hot ...
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3answers
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Should I manually VACUUM my PostgreSQL database if autovacuum is turned on?

I use software which makes a big PostgreSQL database (there is a table with a million rows in it) and the developers says I should VACUUM and ANALYZE periodically. But the PostgreSQL database default ...
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2answers
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How do I know what indexes to create for a table

Is there a way I can figure out the best way to know which indexes to create for a table?
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0answers
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Recovery when failover

1/ Description: I have 2 Centos machine: master, slave (streaming replication). Both of them are built on PostgreSQL 9.3 (image below) and configured failover event (failover PG 9.3 document). Last ...
3
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1answer
181 views

Postgresql 9.3 replication: Preventing wal-files from building up, if receiver goes offline

I have a streaming replication running between two servers. I just upgraded to postgresql 9.3 from 9.2. Earlier on in my 9.2 setup, I have tried that my slave server went offline due to a network ...
2
votes
1answer
759 views

Use GIN to index bit strings

I'm trying to extend PostgreSQL to index bit strings up to 1000 bits. (These bit strings are created by quantization of high-dimensional vectors, so for each dimension up to 4 bits are assigned). ...
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2answers
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PostgreSQL stored procedure to return rows or empty set

I have a stored procedure, which RETURNS SETOF ct_custom_type and inside I do RETURN QUERY EXECUTE 'some dynamic query' And I want to do this: If this 'dynamic query' returns >= 10 rows, I want to ...
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1answer
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How to use psql with no password prompt?

I wrote a script to REINDEX indexes in a database. Here is one of them: echo -e "\nreindex for unq_vbvdata_vehicle started at: `date "+%F %T"`" >> ${LOG_FILE} psql -U ${USERNAME} -h ${HOSTNAME} ...
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6answers
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Are there any good and free tools for managing a PostgreSQL database? [closed]

Before, I have used phpmyadmin to manage an MySQL database, but now I would like to manage a PostgreSQL database. The PostgreSQL database is on a server, but not a webserver, so I don't use PHP. Are ...
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1answer
599 views

Why is there a PostgreSQL Turtle?

I was just checking out the propaganda page for PostgreSQL and I found this little piece of art: It is the "Turtle Style" PostgreSQL logo. How old is this, and did PostgreSQL ever officially use a ...
11
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1answer
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How to get notices to the output stream?

I have debugging messages in functions. Those message are raised like RAISE NOTICE 'Value of id : %', id; I set my log file with \o messages.txt Then I do what I need to do with \i process.sql And ...
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2answers
889 views

How can I generate a random bytea

I would like to be able to generate random bytea fields of arbitrary length (<1Gb) for populating test data. What is the best way of doing this?
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2answers
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PgAdmin III - How to connect to database when password is empty?

I have installed PostgreSQL 9.1 on my PC (Win 7). I have a small Java application connecting successfully to it with login=sa and password="". The connection works. However, it is refused from ...