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.

learn more… | top users | synonyms (1)

6
votes
5answers
12k views

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 ...
6
votes
2answers
5k views

How to promote an existing index to primary key in PostgreSQL

I know how to make a primary key within a table, but how do I make an existing index a primary key? I'm trying to copy an existing table from one database to another. When I show the table, the index ...
6
votes
2answers
5k views

Preventing PostgreSQL from starting on boot in Ubuntu

I am using PostgreSQL 9.2 and it runs automatically when I start the system (Kubuntu). How can I avoid this? I need to start it manually, and I don't want it to start unattended because I need to ...
6
votes
1answer
4k views

How to determine the collation of a table in PostgreSQL?

I want to script a check of the collations used on my tables in PostgreSQL, but googling for Postgresql detect collation is not working well for me, and the documentation is not making this an easy ...
6
votes
3answers
2k views

How to version control PostgreSQL schema with comments?

I version control most of my work with Git: code, documentation, system configuration. I am able to do that because all my valuable work is stored as text files. I have also been writing and dealing ...
6
votes
2answers
2k 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 ...
6
votes
2answers
2k views

Seeting up a PostgreSQL database on another hard drive than my system one on OS X?

I am on OS X 10.8.3, I've install PostgreSQL from macports, but I've realized that I have not enough space on my system drive for the DB I am about to populate with data. Is there a way to create new ...
6
votes
1answer
587 views

What fillfactor for caching table?

I have heavily updated / accessed table where I store serialized java objects. They are in the table for 2-3 hours (also are being updated during that period) and then removed. Size of table is around ...
6
votes
2answers
873 views

SQL ANSI JOIN precedence

I have a query that looks like this: SELECT * FROM TBLA A LEFT JOIN TBLB B ON A.Col1 = B.Col2 RIGHT JOIN TBLC C ON B.Col3 = C.Col4 JOIN TBLD D ON C.Col5 = D.Col6 In which order ...
6
votes
1answer
842 views

Why is CTE open to lost updates?

I don't understand what Craig Ringer meant when he commented: This solution is subject to lost updates if the inserting transaction rolls back; there's no check to enforce that the UPDATE affected ...
6
votes
2answers
105 views

How can I fake inet_client_addr() for unit tests in PostgreSQL?

I have a simple stored procedure whose return value depends on the value of inet_client_addr(). How can I override inet_client_addr() for the purpose of unit tests when testing my stored procedure? ...
6
votes
4answers
243 views

Store millions of rows of denomalized data or some SQL magic?

My DBA experience doesn't go much further than simple storage + retrieval of CMS style data - so this may be a silly question, I don't know! I have a problem whereby I need to lookup or calculate ...
6
votes
1answer
611 views

PostgreSQL PREPARE query with IN () parameters

I'm trying to prepare a query from PHP like: pg_prepare($con, "prep", "select * from test where tid in ($1)"); and then execute it with: $strpar = "3,4,6,8,10"; pg_execute($con, "prep", ...
6
votes
1answer
4k views

How to determine the sweet spot between pool size and database connections in PostgreSQL

We are having trouble handling the traffic during peak hours to our database server. We're looking into improving the hardware (see this question about that side of things) but we also want to work on ...
6
votes
2answers
7k views

Is there a simple way in PL/pgSQL to check if a query returned no result?

I'm currently experimenting a bit with PL/pgSQL and want to know if there is a more elegant way to do something like this: select c.data into data from doc c where c.doc_id = id and c.group_cur > ...
6
votes
2answers
1k views

Single data type for imprecise date values, as allowed by ISO 8601

How can I store date and time values with reduced precision in a PostgreSQL type, and have them behave as date and/or time values? ISO 8601 allows date values with reduced precision. ‘1964’, ...
6
votes
1answer
4k views

Moving postgresql data to different drive

I am using AWS as my cloud environment. I installed PostgreSQL on the same drive as my root instance volume. I have attached and mounted the second drive to my instance. Now I want to move all my ...
6
votes
2answers
1k views

Slow ORDER BY with LIMIT

I have this query: SELECT * FROM location WHERE to_tsvector('simple',unaccent2("city")) @@ to_tsquery('simple',unaccent2('wroclaw')) order by displaycount I'm happy with it: "Sort ...
6
votes
1answer
6k views

How to set Postgresql database to see date as “MDY” permanently

Ho can I set my database to see the 'date' as "MDY" without running: SET datestyle = "ISO, MDY"; every-time I'm trying to access it? I'm using Postgresql version 9.1, Ubuntu 12.04. My system ...
6
votes
1answer
472 views

Can PostgreSQL tell me what configuration files it's using?

I am having trouble with some changes I'm making to a configuration file. I think PostgreSQL is not using the ones I'm modifying. Is there any way to get postgres (maybe some environment variable) to ...
6
votes
2answers
165 views

Count data using multiple date ranges

Probably this has been asked before, but I can't figure it out. I have a phone_clicks table (sql fiddle http://sqlfiddle.com/#!15/855e0/1) CREATE TABLE phone_clicks ( id integer NOT NULL, ...
6
votes
2answers
2k views

Get WAL files from AWS RDS PostgreSQL instance

We have a Postgres RDS instance on Amazon Web Services. We have automatic backups enabled, and we take snapshots on a daily basis. We would like to generate a local 'up-to-date' backup of the RDS ...
6
votes
4answers
14k views

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. ...
6
votes
1answer
678 views

PostgreSQL “freeze”/“unfreeze” command equivalents

In Derby (an embedded database written in Java which is mostly used for testing or prototyping) there are "freeze" and "unfreeze" commands which can be used during an online backup. "Freeze" simply ...
6
votes
1answer
312 views

Privileges required to install PostgreSQL

I am new to PostgreSQL Database. I need to install it in my machine. I am not administrator in my system. Can some one suggest, if Non-Administrator can install it. If there is any other way of ...
6
votes
3answers
10k views

SQL to read XML from file into PostgreSQL database

How can I write SQL to read an XML file into a PostgreSQL XML value? PostgreSQL has a native XML data type with the XMLPARSE function to parse a text string to that type. It also has ways to read ...
6
votes
1answer
4k views

PostgreSQL: COUNT(*) uses a sequential scan, not index

Why does PostgreSQL sequentially scans the table for COUNT(*) query, while there is a very small and indexed primary key?
6
votes
2answers
3k views

How to wrap long lines when SELECTing SQL text columns?

I'm selecting from a table with long text columns. I'd like to wrap long lines to a maximum line length. From: SELECT * FROM test; test_id | text ...
6
votes
1answer
2k views

MATCH FULL vs MATCH SIMPLE

I've noticed a MATCH SIMPLE or MATCH FULL option in phpPgAdmin, but I can't find a description in the docs. How do they function? The default is set to MATCH SIMPLE.
6
votes
4answers
2k views

Cannot shutdown old postmaster when upgrading to Postgres 9.2

I'm upgrading to Postgres 9.2.2 (from 9.1.4). When I try to upgrade the DBs using: pg_upgrade -b /usr/local/Cellar/postgresql/9.1.4/bin -B /usr/local/Cellar/postgresql/9.2.2/bin -d ...
6
votes
1answer
190 views

How should we handle rows which won't be queried once they are old in PostgreSQL?

We have a table in a PostgreSQL database which is growing on the order of millions of rows per day. Each row consists of: ID Foreign user ID Date and time Other data The date and time aren't ...
6
votes
1answer
541 views

PostgreSQL partition hierarchy design for centralized logging

I am looking into setting up logging from all of my servers into a centralized postgresql database. It makes sense to be able to drop logs by date or by host, so I'd like to set it up with ...
6
votes
4answers
2k views

Determine when a PostgreSQL database was last changed

I'm looking at altering how backups are done and am wondering if there is a way to determine which databases in a postgreql cluster have not been recently changed? Instead of using pg_dumpall, I'd ...
6
votes
2answers
139 views

Index that is not used, yet influences query

I've got a PostgreSQL 9.3 table with some numbers and some additional data: CREATE TABLE mytable ( myid BIGINT, somedata BYTEA ) This table currently has about 10M records and takes 1GB of ...
6
votes
2answers
828 views

Is this temp table behaviour documented?

Query Language (SQL) and PL/pgSQL functions treat temp tables differently: begin; create table foo(id) as values (1); select * from foo; /* id ---- 1 */ savepoint s; create function f() returns ...
6
votes
1answer
3k views

How can I request a flush of the postgresql transaction logs?

I have the following problem: a "vertical" Linux distribution (Sophos UMT) comes with PostgreSQL 9.2 to store its configuration. Unfortunately, since the last update, it seems that the transaction ...
6
votes
1answer
10k 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 ...
6
votes
2answers
4k views

Can I have one table be an “alias”, or “symlink”, to another?

I have two tables with the same structure, A and B. A certain application is written so that it always writes the same data to both tables. After a discussion with a colleague about the potential to ...
6
votes
1answer
809 views

PostgreSQL exit status when running a file

When running PostgreSQL with a single SQL command error codes are returned as expected: % psql -c "SELECT * FROM AWDASDASDASDAS" my_db ERROR: relation "awdasdasdasdas" does not exist LINE 1: SELECT ...
6
votes
3answers
1k views

Postgres, MVCC, and Locking

I have a series of SQL statements that look like the following: BEGIN; SELECT counter FROM table WHERE id=X FOR UPDATE; REALLY COMPLEX QUERY; UPDATE table SET counter=Y WHERE id=X; END; I'd like to ...
6
votes
2answers
4k views

How can I update a json element in postgresql json datatype

I can't figure how can I update an element in a postgresql 9.3 datatype. My exemple the db CREATE TABLE "user" ( id uuid NOT NULL, password character varying(255), profiles json, gender ...
6
votes
1answer
561 views

Optimizing PostgreSQL for transient data

I have several tables with 100-300 columns of integer types each, that hold highly volatile data. The datasets are keyed by one or two primary keys, and when refresh occurs, the whole dataset is ...
6
votes
1answer
608 views

How to best use connection pooling in SQLAlchemy for PgBouncer transaction-level pooling?

Using SQLAlchemy to query a PostgreSQL database behind PgBouncer, using transaction-level pooling. What is the best pattern to use for this kind of set up? Should I have one-engine-per-process, ...
6
votes
3answers
5k views

PostgreSQL Sequential Scan instead of Index Scan Why?

Hi All I've got a problem with my PostgreSQL database query and wondering if anyone can help. In some scenarios my query seems to ignore the index that I've created which is used for joining the two ...
6
votes
1answer
303 views

in postgres, can one optimize a table across partitions?

in a database with many companies, segregating them using schema and search_path almost all access comes at the company level, that is, limited to a single schema. some data-warehouse and accounting ...
6
votes
2answers
3k views

Non-unique multicolumn foreign key

I have a "comments" table that models a conversation on a topic, like this: id serial topic_id integer parent_comment_id integer body text So, every comment has a reference to its topic AND ...
6
votes
1answer
282 views

Hierarchical structure with limited number of records per user

I am planning schema for an affiliate network. For all hierarchical queries I am using Postgres tablefunc extension but here is another problem. Any user can refer only 3 other users at max. So for ...
6
votes
1answer
295 views

Can we use old primary to sync with standby after failover in PostgreSQL?

If my standby (postgres) is behind by few seconds before failover. What is the easiest way to sync back my old primary after failover in PostgreSQL. In Oracle we have the option of Reinstating a ...
6
votes
3answers
375 views

Is using SUM() twice suboptimal?

I know I have to write SUM twice, if I wish to use it in a HAVING clause (or use a derived table otherwise): SELECT id, sum(hours) AS totalhours FROM mytable GROUP BY id HAVING sum(hours) ...
6
votes
1answer
222 views

How to dive into the PostgreSQL's optimizer and trace each step it takes to optimize the query?

Just like the MEMO structure in SQL Server which is kind of a "paper trail" of steps the optimizer takes in optimizing the query. Does PostgreSQL have the similar structure which records steps the ...