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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Is replication from SQL Server 2008 to PostgreSql possible?

Is it possible ? Sql Server as publisher(master) and PostgreSql as slave(subscriber) ? Any type of replication really.
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pg_dump from 9.2 to 8.4 [closed]

I'm trying to restore a db dump from PostgreSQL 9.2 to PostgrSQL 8.4 (from separate machines, both are running Windows 7). I followed the instructions in this answer: Use pg_restore to restore from ...
3
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1answer
932 views

Is it safe to call pg_ctl reload while doing heavy writes?

I am running Postgres 8.4, and I would like to change the authentication method for a user. It's my understanding that I have to do this in pg_hba.conf, and then reload the configuration files with ...
3
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1answer
6k views

Select first row (grouping) + add aggregate function

First have a look at this question on StackOverflow. I'm looking to accomplish the same task, except I also need to add an aggregate function (PostGIS's ST_Union) to my query. How can I combine the ...
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2answers
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Can't connect to the postgres server ls: /tmp/.s.PGSQL.5432: No such file or directory

*Update*I included an update at the bottom of this post with details from the logs explaining the problem that I haven't been able to fix. Following along with this Railscast ...
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2answers
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Changing PostgreSQL port using command line

My PostgreSQL default port is 5432, I want to change default port by using command line (in Windows 7). I saw this solution before: http://stackoverflow.com/questions/187438/want-to-change-pgsql-port ...
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4answers
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Daily and Differential Backups [closed]

Is there a program with which I can create daily MySQL, PostgreSQL and MariaDB backups with these requirements: The first time, make a full backup. The second time, only the changes since the last ...
3
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1answer
1k views

Use cases for hstore vs json datatypes in postgresql [closed]

In Postgresql, the hstore and json datatypes seem to have very similar use cases. When would you choose to use one vs. the other? Initial thoughts: You can nest with json; you can't with hstore ...
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4answers
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Database design - People and Organisations

Databases are not my primary skill and I am finding I need some assistance please. The software we are building has "Customers". The Customer could either be a Person or an Organisation. I really ...
5
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1answer
325 views

force PostgreSQL into recovery mode

I have a somewhat strange question. Is there a way to manually force PostgreSQL into recovery mode? I've not been able to find aything in the documentation. I've been working with a script ...
3
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1answer
124 views

Why do psql queries take longer when inserting many rows. Why is it non linear

So if I insert a single row into a postgres database it takes 18 ms. If I do this in a loop like this: INSERT INTO contacts (numbers) SELECT distinct array[ (random() * 99999999)::integer, ...
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1answer
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Foreign Key to Multicolumn Primary Key?

I have three connected table in my design. Basic logic is when a category deleted, also delete records in category_product table which has deleted category's id in its cat_id column. But when I tried ...
0
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1answer
326 views

Postgres - Schema information within Trigger?

Background : (Multi-tenant design;separate schema per customer, all table structures identical;Data-warehouse / non-OLTP system here; Postgres 9.2.x). Reviewing patterns for the following problem: I ...
1
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1answer
208 views

OK to put temp tablespace on volatile storage or to omit it from backups? (Postgresql)

I would intuit that it's fine, but I just want to make sure there are no gotchas from a recovery point of view: If I were to lose my temp tablespace upon system crash, would this prevent proper crash ...
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0answers
132 views

PostgreSQL datasource URL?

My first attempt to use PostgreSQL: I have the elephant icon on the top right: running on port 5432. I want to use LibreOffice as an interface: Connect to an existing database: PostgreSQL ...
1
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1answer
2k views

PostgreSQL stored function that returns arbitrary resultset

I would like to write a PostgreSQL stored function that essentially behaves like the stored procedures I know and love from MSSQL and MySQL where I can just wrap a query that takes no parameters and ...
2
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2answers
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Read Committed Isolation Level

Quote from docs: Read Committed is the default isolation level in PostgreSQL. When a transaction uses this isolation level, a SELECT query (without a FOR UPDATE/SHARE clause) sees only data ...
4
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1answer
15k views

Performance difference between MySQL and PostgreSQL for the same schema/queries [closed]

I'm a newbie DBA, and I have experience in Microsoft SQL Server but I want to jump to FLOSS. I'm starting a company, and we develop an app (PHP) with a Postgres backend, and we did some tests ...
1
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1answer
461 views

Table for optional parent/child relationship

Assuming we have the following table: Item, Parent, Child and Parent is the parent of child. The item can either belong to a parent or child and not both. I have other tables that are similar to ...
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0answers
394 views

PostgreSQL: Slave doesn't replicate the Master's data

I'm using PostgreSQL 9.2.3 on both computers, both of which run Win2008R2. I've setup streaming replication by following this guide: ...
4
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2answers
559 views

Is it ever a good idea to denormalize for integrity?

I'm using Postgres 9.2 to develop a quiz app, in which I present the user with a series of problems and record their answers. These problems can take a variety of forms - they might be multiple ...
0
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1answer
47 views

Storing no of players the last seven days in an online game

I want to plot the number of players, in the last seven days, of an MMORPG which haves 50~ servers. The system fetches the number of players in each server every 15 minutes and I'm not really sure how ...
4
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1answer
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Postgres: count(*) vs count(id)

I saw in the documentation the difference between count(*) and count(pk). I had been using count(pk) (where pk is a SERIAL PRIMARY KEY) not knowing about the existence of count(*). My question is ...
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2answers
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Dropping a group of schemas with similar name patterns

Consider a situation where one need to perform a bunch of essentially identical operations, with the only variable being the name of some object. In my case, I need to drop some schemas, all of the ...
3
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3answers
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Getting SELECT to return a constant value even if zero rows match

Consider this select statement: SELECT *, 1 AS query_id FROM players WHERE username='foobar'; It returns the column query_id with value 1 along with a player's other columns. How would ...
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1answer
278 views

Should I keep pg_xlog on the same disk as data if using disk snapshotting?

We're running on EBS volumes on EC2. We're interested in leveraging EBS snapshotting for backups. However, does this mean we'd need to ensure our pg_xlog is on the same EBS volume as our data? (I ...
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2answers
10k views

Optimizing bulk update performance in PostgreSQL

Using PG 9.1 on Ubuntu 12.04. It currently takes up to 24h for us to run a large set of UPDATE statements on a database, which are of the form: UPDATE table SET field1 = constant1, field2 = ...
8
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1answer
12k views

Usage of COPY FROM STDIN in postgres

I just started using Postgres and I'm trying to create a sample db to understand its functions, looking around, I found some scripts in pgfoundry.org. I understand the commands, since I previously ...
0
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1answer
891 views

Cannot create PostgreSQL user

I'm using PostrgreSQL 9.1.9 on Ubuntu 13.04. Using the following StackOverflow question, I tried to create a user/role in postgressql: ...
3
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2answers
5k views

Creating a PostgreSQL SERIAL column using pgAdmin3

When I use pgAdmin3 to create a column of type serial, why does it instead create nextval('prices_id_seq'::regclass)? Should we keep this type defined by pgAdmin? Manually create the table with SQL ...
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2answers
241 views

“Rewinding” a Postgresql database

I have heard that Postgresql uses an append-only format for it's databases, and if this is true I should be able to 'rewind' the database to a previous point in time by removing the commits that came ...
4
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1answer
338 views

Is there better way to 'touch' a row than performing a dummy update?

I use the xmin system column to implement a form of optimistic locking, and sometimes need to 'touch' the row to bump xmin without actually updating the row. I currently just do a 'dummy' update: ...
1
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1answer
158 views

PostgreSQL socket not listening on the right one

I'm trying to get my PostgreSQL to work. It is clearly running, according to: ps aux | grep postgres | grep -v grep I am getting - username 5781 0.0 0.0 2441364 524 ?? Ss ...
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1answer
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PosgreSQL: setting high work_mem does not avoid disk merge

This is not quite my day with postgres. On my server machine with PosgreSQL 9.2.3 I have set work_mem to 4MB to avoid Sort Method: external merge Disk: 2072kB but it did not help: cwu=# vacuum ...
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2answers
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Why PostreSQL 9.2 does not use index scan if it can?

My PosgreSQL planner (9.2) does not pick index and rather choose to do seq scan. Here is my table. The index I am talking about is name_left_prefix cwu=# \d web_city; ...
3
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1answer
5k views

Error “column does not exist” in a SELECT with JOIN and GROUP BY query

I'm using PostgreSQL 9.1 with a Ruby on Rails application. I'm trying to list the last version of each "charge" (in my history table : hist_version_charges) belonging to the same project id ...
1
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2answers
330 views

Error installing pgcrypto extension [closed]

I want to install the pgcrypto extension on my postgresql installation on Windows. I found that I just have to call CREATE EXTENSION pgcrypto; but I've got an error : Syntax error on « CREATE » LINE ...
0
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2answers
277 views

Storing data in PostgreSQL: One table or two?

I've just started using PostgreSQL 9.2 and my data consists of product prices at various points in time, usually a different price every month. Question: Because every product can have different ...
1
vote
1answer
116 views

Does PostgreSQL work well as a workstation-based DBMS?

I've been considering PostgreSQL for an application I am writing in .NET WinForms, and the app is intended to be standalone with occasional sync-ing with a web service. I plan to use Sql Server for ...
2
votes
1answer
180 views

Mismatch between size computed from pg_buffercahce Vs shared_buffers in postgresql?

I have a rather naive question regarding the size of shared_buffers computed from pg_buffercache and the shared_buffers size mentioned in postgresql.conf. Based on my understanding pg_buffercache ...
1
vote
1answer
600 views

Postgres: Given some parent id's how can I SELECT X child records for each?

In Postgres, if I have : Parent Table id, name 1, Parent1 2, Parent2 ..... 5, Parent5 Child Table id, parent_id, name 1, 1, Child1 2, 1, Child2 ..... 6, 2, Child6 ..... 25, 5, Child25 so 5 ...
2
votes
2answers
776 views

Creating sequence for longer numeric values

I need to create a database model that includes a field to store 20 digit unique values. Which will be used by many clients over an API. The value must be 20 digit long, numeric and unique. Best ...
2
votes
2answers
519 views

PostgreSQL and default Schemas

Whenever I create a brand new database in PostgreSQL Maestro it creates the following list of default schemas: Now from my understanding Schemas are like folders for organization, etc. So the ...
2
votes
2answers
3k views

Get all partition names for a table

I want to list all the partitions created by dynamic triggers in PostgreSQL 9.1. I was able to generate a count of partitions using this related answer by Frank Heikens. I have a table foo with an ...
2
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1answer
739 views

How to get user-specific settings in PostgreSQL?

I have to collect some information of PostgreSQL roles. One piece of information is whether the role has different settings than 'usual', usual meaning here default values for only a few parameters ...
2
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2answers
156 views

Different queries result in big difference in performance

I have 2 similar functions, different way result in big diff in performance. The PostgreSQL version: 9.2.1. Function 1 create or replace function func_1() returns text as $$ declare v_i ...
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1answer
221 views

Equivalent of MRG_MYISAM in databases other than MySQL? [closed]

Does anyone know if other database have something equivalent to MRG_MYISAM (aka the MERGE table type/storage engine)? I know about fragmenting, but this is not quite the same AFAIK. We're using ...
4
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1answer
5k views

PostgreSQL: Cannot change directory to /root

I am trying to copy a table planet_osm_polygon from one database osm to another test. I su postgres and performed the pg_dump. Problem: However I'm getting the error could not change directory to ...
3
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0answers
321 views

How to count selectivity rows in PostgreSQL 8.2

I have problem with two queries on PostgreSQL v8.2. It seem like the optimizer chooses a wrong index: db=# explain select count(*), messagetype, alias from event where templateinfoid = 10 and ...
6
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1answer
3k views

Recovering a dropped table in PostgreSQL

I have : CREATE TABLE ketoan_vn.Customers ( CustomerId character varying(10) NOT NULL, CustomerName character varying(150), CONSTRAINT Customers_PK_CustomerID PRIMARY KEY (CustomerId) ); I ...