PostgreSQL is a powerful, enterprise class, open source RDBMS. It has more than 15 years of active development and a proven architecture that has earned it a strong reputation for reliability and data integrity. It runs on all major operating systems, including Linux, UNIX and Windows. It prides ...
0
votes
1answer
59 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 ...
0
votes
1answer
59 views
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 ...
2
votes
2answers
63 views
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
...
1
vote
4answers
153 views
Daily and Differential Backups
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 ...
0
votes
0answers
36 views
Backup daily for MySQL, MariaDB or PostgreSQL [duplicate]
Good day:
I wonder if there is a program with which I can create daily backups with these requirements:
The first time, make a full backup.
The second time, only the changes since the last backup, ...
-1
votes
1answer
80 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
...
1
vote
4answers
128 views
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 ...
4
votes
1answer
39 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
votes
1answer
36 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,
...
1
vote
1answer
31 views
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
votes
1answer
39 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 ...
0
votes
1answer
20 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 ...
1
vote
0answers
28 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
...
0
votes
1answer
41 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 ...
1
vote
2answers
44 views
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 ...
0
votes
0answers
84 views
Performance difference between MySQL and PostgreSQL for the same schema/queries
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
vote
1answer
58 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 ...
0
votes
0answers
48 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
votes
2answers
226 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
votes
1answer
36 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 ...
2
votes
1answer
88 views
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 ...
1
vote
2answers
42 views
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 ...
1
vote
2answers
88 views
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 ...
0
votes
0answers
28 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 ...
2
votes
2answers
95 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 = ...
0
votes
1answer
85 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
votes
0answers
24 views
Query Postgres For Combinations Where Both values are Unique to Each Other [migrated]
Confusing title, let's see if I can explain.
I have a large Database of Records. The values of interest are an EIN and A Registration Number.
There are lots of records for each value.
What I want ...
0
votes
1answer
26 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:
...
1
vote
2answers
54 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 ...
1
vote
2answers
47 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
votes
1answer
45 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
vote
1answer
28 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 ...
1
vote
1answer
31 views
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 ...
1
vote
2answers
26 views
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;
...
0
votes
1answer
90 views
Error “column does not exist” in a SELECT with JOIN and GROUP BY querry
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
vote
0answers
30 views
Failover - automatic switching between servers in Postgresql 9.1
I'm pretty new to Postgresql 9.1 and failover replication. We have a simple master-slave setup, for failover replication, which our application (client) is connected to. On a failure of the master, ...
0
votes
2answers
28 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
votes
2answers
67 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
34 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
20 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
40 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
54 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
66 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 ...
1
vote
1answer
70 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 for tables which are partitioned using Frank Heikens' answer in ...
1
vote
1answer
25 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
votes
2answers
91 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 ...
1
vote
1answer
49 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 ...
2
votes
1answer
63 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
votes
0answers
46 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 ...
4
votes
1answer
62 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 ...
