Questions tagged [postgresql]

All versions of PostgreSQL. Add an additional version-specific tag like postgresql-11 if that context is important.

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729 views

PostgreSQL vs MySQL benchmarks when a 2nd level cache is included

Has anyone been able to find any benchmarks comparing PostgreSQL and MySQL performance when they are used by a system through Hibernate (or another comparable ORM) and the 2nd level cache (backed by ...
15
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2answers
10k views

Index on primary key not used in simple join

I have the following table and index definitions: CREATE TABLE munkalap ( munkalap_id serial PRIMARY KEY, ... ); CREATE TABLE munkalap_lepes ( munkalap_lepes_id serial PRIMARY KEY, ...
3
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1answer
904 views

querying a linked PostgreSQL database in SQL Server 2008

We will be deploying an application with a Postgres back-end and need to provide report writing capabilities in SQL Server. I am exploring options for real-time or near real-time reporting in this ...
60
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3answers
37k views

What are the drawbacks with using UUID or GUID as a primary key?

I would like to build a distributed system. I need to store data in databases and it would be helpful to use an UUID or a GUID as a primary key on some tables. I assume it's a drawbacks with this ...
4
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2answers
4k views

Improving performance of nasty nested-view joins

I have a moderate-sized database spread out over a few tables, the rough architecture is: Input Data (Data ID, Session ID and a few fields of statistical importance) Input File (Data ID and a blob) ...
9
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1answer
7k views

Fast general method to calculate percentiles

I want to find n>1 percentiles of an unsorted column in PostgreSQL. For example the 20th, 40th, 60th, 80th and 100th percentile. An obvious solution is to count and sort the column and then do a ...
2
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1answer
16k views

How to export a table on postgresql command line

Anyone can do tell me how to do that? (I know maybe is a dumb question but I'm trying to learn how to use command line of postgresql) ~$ psql mybase psql (9.1.3) Type "help" for help. and then ...
2
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1answer
2k views

Dropping indexes doesn't seem to release space to the OS. Can it?

I'm running PostgreSQL 9.1. I have noticed really alarmingly bad indexes are taking up a lot of space on my server, e.g: evlampts=# SELECT pg_size_pretty(pg_relation_size('mcdata_2011_07')) AS ...
5
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1answer
2k views

Concurrency with Select-conditional Insert/Update/Delete - PostgreSQL

I have an intervals table which stores a start date and an end date for variables variable_id (four columns : id, start, end, variable_id). Clients compute new intervals for one variable and store ...
1
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2answers
933 views

pg_upgrade fails with an unspecified error

I’m running Postgres 9.1’s pg_ugrade to migrate from 9.0 to 9.1 on Windows x64. After editing the permissions to allow full trust, running the tool as the postgres user, and working around a bug ...
1
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1answer
1k views

slow index scan on postgresql 9.1

I have a view which is amazingly slow :) It joins two tables only, having a few simple WHERE conditions and one in a form of a subquery (see SubPlan1 below). The simplest condition is checked as an ...
2
votes
1answer
4k views

pg_restore: [archiver] unsupported version (1.11) in file header postgresql

My server is working on Ubuntu with PostgreSQL 8.4 and the development machine I'm using has Debian Lenny with PostgreSQL 8.3. My machine can't be upgraded to PostgreSQL 8.4 and I need to restore a ...
3
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4answers
5k views

migrating tables from Postgres to SQL Server 2008

(I fear what I wish to accomplish shall not be easy, but a lot of my googling around about it yielded rather dated results, so here it goes...) I have a Postgres 8.4.x database with over 100 tables. ...
0
votes
1answer
344 views

Update Postgres on server that already has version included with system

Mac OS X (Lion) Server includes Postgres (9.0.5) that it uses for some system utilities (Wiki server, caldav, etc.). I'm about to start using this server for some Rails applications and am wondering ...
2
votes
2answers
624 views

pg_relation_size does not show any difference after VACUUM ANALYZE

I wrote a script to backup a postgresql using COPY and then delete those records. I have used pg_relation_size before and after delete. pg_relation_size DELETE VACUUM ANALYZE pg_relation_size But ...
4
votes
2answers
2k views

psql won't list databases

I have a situation that I'm scratching my head over, but I'm new to postgresql, so I may be overlooking something obvious. I set up a testbed server and set access in pg_hba.conf: local all ...
2
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2answers
2k views

Request suggestion for a database between MySQL and Postgresql

We maintain a list of all the SAN Switch Ports that are either free or allocated to hosts. Currently, we enter the information on the company portal. But we need to move if off to a database because ...
0
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1answer
132 views

What DML commands can be allowed / limited on a reporting server?

I have a largish database (PostgreSQL 9.1) which I'm preparing to replicate using streaming replication. The 2nd server will be used for reporting and backup purposes. When building reports, it's ...
2
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1answer
338 views

Postgres synchronized backup - what's with the archive?

I am setting up a Postgres 9.1 master and a hot standby-server. I read the documentation but I'm not quite sure yet what I should do with my WAL files. Every commit is done on both servers before ...
2
votes
1answer
319 views

Working of window functions and idea window size for window function

I am not able to understand the concept of window functions. How exactly they work and what are the pros and cons of such technique? I have read that using limit and offset is slow but its still used....
1
vote
2answers
2k views

Backup of Postgres database

I want to create a backup of my database in Postgres. I'm using pgAdmin. on my database I have clicked right button of mouse after that I've selected the "Create a backup of database" After that I'...
3
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1answer
4k views

Disable automatic login in pgAdmin

I have enabled automatic login in pgAdmin and would like to disable it to make it possible to connect to the servers using different roles. How do I do this?
4
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2answers
8k views

Reindexing a large database

I have a very large database (millions of rows) which has been indexed. I receive a diff of rows from another source that I need to update in my database. The problem I am facing is that is it ...
2
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1answer
235 views

postgresql - transaction log - versioning?

Is it possible to "version" your database so that any change can be reviewed or roll backed? Obviously backups are important but being able to go back to any previous state of the database (at least ...
6
votes
1answer
259 views

Upgrade postgres without messing with ports?

The standard procedure for upgrading Postgres appears to require that I temporarily run both the old and the new version. This means that I have to change the port of the old version. This seems ...
2
votes
2answers
951 views

Attempting to avoid SORT in query planner

I have a query that is used VERY frequently in my application. Without modifying the query itself, I'm trying to optimize it by toying with different indexing schemes. Here's the query (basically): ...
4
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1answer
5k views

PostgreSQL Scheduled Database Backup

For scheduling a daily back up on a postgres database we execute the following command: 0 2 * * * /usr/local/pgsql/bin/pg_dump -Fp -b -U database_name \ > $HOME/db_backups/database_name-`...
2
votes
1answer
3k views

How to import the data of postgres 8.x to postgres 9.x

My OS is windows 7 x64. I was use postgres 8.4, and all databases are in postgres/8.4/data. Yesterday, I reinstalled my os system, but I found I can't install postgres 8.4 anymore (there is always an ...
6
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2answers
4k views

Is Tablespace something like Logical Volume?

I'm confused about tablespaces in PostgreSQL. Is it something like LVM? I mean when disk is getting full, can we add another disk, format and then CREATE TABLESPACE tblspace LOCATION /media/disk2/data?...
2
votes
1answer
2k views

Triggers not being run on a partitioned table

I'm using PostgreSQL. I have a table that I have partitioned into three sub-tables - and as far as I can tell, this all works correctly. Rows are correctly inserted into the appropriate partition and ...
4
votes
2answers
811 views

Huge database logging of event type rows and ways to optimize it

We have a database that stores events. Events are generated at a 1000 per sec rate. We need to keep these events accessible for some years. Usual use of these events is selecting some of them from the ...
2
votes
1answer
530 views

Query takes hours

Up until now all queries in my PostgreSQL application were fast. During the last days, sometimes a query takes several hours. Index are healthy, because after dump, restore, vacuum -z, it is still the ...
1
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1answer
152 views

Impact of changing schema name

I have a server with two databases. Each database has a different schema name despite the fact that DB2 is a subset of DB1 (DB2 has a subset of the tables in DB1). Not withstanding any code changes ...
5
votes
4answers
3k views

Trouble setting up Postgres for the first time

I have some, albeit limited, experience with MySQL and MongoDB (both running fine on server) but having trouble with Postgres and find the documentation lacking for newbies, like myself. Postgres is ...
2
votes
1answer
292 views

Streaming Replication on Two Postgres Systems?

There's two servers, a Primary Server and a Backup Server. Both have Postgres installed. The Primary Server has one database, and the Backup Server has two - one for a warm backup/standby of the ...
11
votes
1answer
8k views

Postgresql performed a “fast shutdown” by itself. Why? How was it able to do that?

I've already googled and manual read as much as I could before posting this here. Version info: Postgres8.4 on Ubuntu10.x I have a personal laptop that I run a postgres server on, and a Java script ...
2
votes
2answers
8k views

Joining based on date (or date range)

I'm not sure if I've completely fudged the design of my small hobby database (I'm not a DBA by any means), but I have a table like this (primary key is (staffid, effectivefrom)): staffid | target | ...
1
vote
1answer
322 views

Postgres shared_buffers and pooled processes

I have read several articles (including Postgres docs) that suggest setting the shared_buffer's config value to 25% of your total physical memory. Using my 4 GB memory as an example... If I ...
1
vote
1answer
5k views

Postgres: trying to fix some unicode encoding issues

I've got a postgres 8.4 database with a few mangled characters in one of the columns on a table. For example, the word "don't" gets displayed within psql as: donâ\u0080\u0099t I want to be able to ...
7
votes
2answers
11k views

Fastest validation query in PostgreSQL

What is the fastest query in PostgreSQL, which I can use as a validationQuery binding a JNDI resource? I though that SELECT 1 is the simplest, but in this document it is said that in PostgreSQL we ...
7
votes
2answers
3k views

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 dimensions ...
5
votes
1answer
3k views

WAL backups with pg_dump not possible?

I am hoping to move to WAL backup from pg_dump. But I am confused by this note in 4.3 documentation: Perform the backup, using any convenient file-system-backup tool such as tar or cpio. And in ...
0
votes
2answers
228 views

New PostgreSQL 9.1 configuration doesn’t work

I changed the length of table names in PostgreSQL in the file pg_config_manual.h (in C:\Program Files\PostgreSQL\9.1\include) to 128. Then I reloaded the new configuration by selecting menu "Reload ...
5
votes
2answers
3k views

Span single transaction over several sequential psql sessions

I am running PostgreSQL 8.4 database server and psql terminal front-end on Ubuntu 10.04 Lucid Lynx and would like to span a single transaction over several sequential psql sessions. When I connect to ...
0
votes
1answer
214 views

How to improve restoring the PostgreSQL database?

I'd like to restore the PostgreSQL database from a dump. The below command works fine for me: CALL "%PGBIN%\pg_restore" -c -d NetCatalog %DUMPFILE% How can I add a few lines to my .bat file to ...
2
votes
1answer
2k views

Postgres - how to randomize two columns in a table

I have a table of User data which I would like to disguise/anonymize. Two of the columns have location data (e.g. lat and long, both BigDecimals). I have anonymized all the names and other ...
1
vote
1answer
326 views

Show all variations of 2 characters in postgres

How would I do this in postgres : Lets say I have an x and a y and I want to show all possible combinations : xx yy xy yx How can I make postgres do this for me ?
1
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1answer
8k views

Postgres Administration roles

I need to work with a remote postgresql server. My application needs to perform the following actions: to be able to create/drop database (I only need to work with 1 specific database) to be able to ...
2
votes
2answers
222 views

Validation of availability for a new order

I have a management application of sales, stock and payment on a warehouse whole saler from a web interface. In particular, when a order is effectuated it must create a line corresponding to each ...
4
votes
1answer
2k views

How can I escape XML field in XML-output query?

I have following request: SELECT XMLAGG(data) FROM (SELECT XMLELEMENT(name item, XMLFOREST( title, body as description, date_created as date, 'http://example.com/news'||id as link )) AS ...