Questions tagged [postgresql]

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

Filter by
Sorted by
Tagged with
22
votes
2answers
10k views

How to store time series data

I have what I believe is a time series data set (please correct me if I'm wrong) that has a bunch of associated values. An example would be modeling a car and tracking its various attributes during a ...
22
votes
1answer
53k views

How to connect to an remote PostgreSQL database on Ubuntu using pgAdmin3?

I'm trying to setup a PostgreSQL database on an Ubuntu machine. I would like to be able to access it using pgAdmin3 from a remote machine. How do I setup this? I have installed the PostgreSQL ...
22
votes
3answers
13k views

Replace a materialized view in Postgres

I have a materialized view in Postgres 9.3 that I'd like to update with new columns. However, other materialized views also depend upon this view, and the error message indicates that dropping a view ...
22
votes
2answers
18k views

What is the Maintenance DB asked by pgAdmin?

pgAdmin dialog for adding new database connections asks for a "Maintenance DB". In order to be able to connect, I set it to the database I want to connect (and also, I have the rights to connect). So,...
22
votes
1answer
6k views

Is there a good way to run a trigger for each record in a postgres table?

I have a system where I can't control the design of some tables (replicated via Slony-I), and so I have a series of what we refer to as 'shadow tables', where I extract some information out of the ...
22
votes
2answers
5k views

What is the modern way to partition PostgreSQL across machines, when the data is “naturally partitionable”

After several years of dwelling into the "NoSQL" space, now I have a problem that is quite "relational" in its nature. Today I see data stores with quite different eyes than before. Things like Riak ...
21
votes
2answers
28k views

Postgres multiple columns to json

I am running postgresql 9.3.4. I have a table with 3 fields: id name addr --- ---- ---- 1 n1 ad1 2 n2 ad2 ... I need to move the data to a new table with fields like: id data --- ...
21
votes
1answer
33k views

Number of active connections and remaining connections

I would like to get statistics about the peak number of connections over a period of time. I know the pg_stat_activity view, like select count(*) from pg_stat_activity, but I think this method is not ...
21
votes
1answer
12k views

Why does NOT IN with a set containing NULL always return FALSE/NULL?

I had a query (for Postgres and Informix) with a NOT IN clause containing a subquery that in some cases returned NULL values, causing that clause (and the entire query) to fail to return anything. ...
21
votes
5answers
47k views

PostgreSQL: How to backup only One Schema from a database and restore it on another server

I have a database named "A" which has two schemas "B" and "C". I want to backup and restore Schema "B" on a different server? not sure how to do this as I am new to Postgres. Do I have to create a new ...
20
votes
1answer
42k 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 ...
20
votes
2answers
56k views

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 ...
20
votes
2answers
301k views

Using SELECT in the WHERE clause of another SELECT

I have made a draft remote application on top of libpq for PostrgreSQL. It behaves well, but I have profiled the general functioning of the application. For each final business result that I produce, ...
20
votes
2answers
21k views

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 query's results is ordering it according to the user's language during the ...
20
votes
2answers
8k views

PostgreSQL procedural languages - differences between PL/pgSQL and SQL

Can anybody please summarize the differences between: http://www.postgresql.org/docs/9.1/static/xfunc-sql.html and http://www.postgresql.org/docs/9.1/static/plpgsql.html ? Main points: ...
20
votes
6answers
4k views

Count where two or more columns in a row are over a certain value [basketball, double double, triple double]

I play a basketball game which allows to output its statistics as a database file, so one can calculate statistics from it that are not implemented in the game. So far I've had no problem caluclating ...
20
votes
3answers
12k views

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 ...
20
votes
7answers
31k views

How to convert a MySQL database to PostgreSQL?

Is there any command line tool for converting the MySQL database to PostgreSQL? I'd also like to know if there is a way to convert the database using the normal mysqldump command.
20
votes
4answers
7k views

Combining separate ranges into largest possible contiguous ranges

I'm trying to combine multiple date ranges (my load is about max 500, most cases 10) that may or may not overlap into the largest possible contiguous date ranges. For example: Data: CREATE TABLE ...
20
votes
1answer
24k views

What is the meaning of n_live_tup and n_dead_tup in pg_stat_user_tables

What is the meaning of n_live_tup and n_dead_tup in pg_stat_user_tables or pgstattuple?
20
votes
2answers
27k views

Most efficient way of bulk deleting rows from postgres

I'm wondering what the most efficient way would be to delete large numbers of rows from PostgreSQL, this process would be part of a recurring task every day to bulk import data (a delta of insertions +...
20
votes
5answers
15k views

Best cloud platform for PostgreSQL [closed]

Currently, in our project, we use dedicated servers for our PostgreSQL database. In theory, we can run anything on some cloud platforms. However, PostgreSQL configuration is strictly related to ...
20
votes
3answers
28k views

How to optimization database for heavy I/O from updates (software and hardware)

The situation I have a postgresql 9.2 database which is quite heavily updated all the time. The system is hence I/O bound, and I'm currently considering making another upgrade, I just need some ...
20
votes
3answers
22k views

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 ...
19
votes
6answers
19k views

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 ...
19
votes
1answer
101k views

How can I convert a string to a double precision in PostgreSQL? [closed]

How can I convert a string to a double precision in PostgreSQL ? I tried something like : update points set latitude2 = cast(latitude as double) ; where latitude is a string and latitude2 is a ...
19
votes
2answers
19k views

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 ...
19
votes
2answers
30k views

How to best store a timestamp in PostgreSQL?

I'm working on a PostgreSQL DB design and I am wondering how best to store timestamps. Assumptions Users in different timezones will use the database for all CRUD functions. I have looked at 2 ...
19
votes
2answers
11k views

How to create an index to speed up an aggregate LIKE query on an expression?

I may be asking the wrong question in the title. Here are the facts: My customer service folk have been complaining about slow response times when doing customer lookups on the administration ...
19
votes
6answers
38k views

PostgreSQL Change owner of all tables under a specific schema

I am trying to change the owner of all tables under the same schema in one command line. i.e: alter table schema_name.* owner to newowner. Is there a way to accomplish that?
19
votes
1answer
66k views

Rolling sum / count / average over date interval

In a database of transactions spanning 1,000s of entities over 18 months, I would like to run a query to group every possible 30-day period by entity_id with a SUM of their transaction amounts and ...
19
votes
3answers
18k views

In PostgreSQL, is there a type-safe first() aggregate function?

Full question re-write I'm looking for a First() aggregate function. Here I found something that almost works: CREATE OR REPLACE FUNCTION public.first_agg ( anyelement, anyelement ) RETURNS ...
19
votes
3answers
17k 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 ...
19
votes
7answers
8k views

Efficiently select beginning and end of multiple contiguous ranges in Postgresql query

I've got about a billion rows of data in a table with a name and an integer in the range 1-288. For a given name, every int is unique, and not every possible integer in the range is present--so there ...
19
votes
2answers
2k views

Why are the plans different if the queries are logically alike?

I wrote two functions to answer Day 3's first homework question from Seven Databases in Seven Weeks. Create a stored procedure where you can input a movie title or actor's name you like, and it ...
19
votes
3answers
8k views

PostgreSQL: Can I do pg_start_backup() on a live, running db under load?

Our established replication has broken ("requested WAL segment has already been removed" during downtime) We cannot easily stop the master again. Can we do pg_start_backup(), rsync ${PGDATA}/ ...
19
votes
2answers
34k views

Disable all constraints and table checks while restoring a dump

I've obtained a dump of my PostgreSQL database with: pg_dump -U user-name -d db-name -f dumpfile which I then proceed to restore in another database with: psql X -U postgres -d db-name-b -f ...
19
votes
1answer
2k views

Is it worth it to run VACUUM on a table that only receives INSERTs?

In a 2015 re:Invent talk, AWS mentioned that vacuum should be run not only after updates or deletes but also after inserts. Here is the relevant part of the talk: http://www.youtube.com/watch?v=...
18
votes
4answers
21k views

Find IDs from a list that don't exist in a table

Say I have the following schema and data: create table images( id int not null ); insert into images values(1), (2), (3), (4), (6), (8); I want to perform a query like: select id from images ...
18
votes
2answers
18k views

Query the definition of a materialized view in Postgres

I'm wondering how to query the definition of a materialized view in Postgres. For reference, what I hoped to do is very similar to what you can do for a regular view: SELECT * FROM information_schema....
18
votes
2answers
6k views

Custom unique column constraint, only enforced if one column has a specific value

Is it possible to have a custom unique column constraint as follows? Suppose I have two cols, subset and type, both strings (though the data types probably doesn't matter). If type is "true", then ...
18
votes
1answer
2k views

What is the special database “postgres” for?

I have a PostgreSQL server with several databases running on it. One of the databases is called postgres, and it was there right from the beginning. I could not see any tables inside and I've never ...
18
votes
2answers
10k views

Is a Postgres long-running query aborted if the connection is lost/broken?

If I open a connection to Postgres and issue a long-running query, and then break the connection (e.g., kill the client process that opened the connection), will the long-running query continue to run,...
18
votes
2answers
5k views

Postgres query plan of a UDF invocation written in pgpsql

It's possible when using the pgadmin or plsql to get a hold of a query plan for a sql statement executed via a UDF (using EXPLAIN). So, how do I get a hold of the query plan for a particular ...
18
votes
3answers
27k views

Postgresql doesn't accept replication connection

Plain old streaming replication. PostgreSQL: 9.2.7 Windows 8.1 64 bit My primary and secondary clusters are on same windows machine. I have already done pg_start_backup() and everything, so both ...
18
votes
5answers
122k views

Query to return output column names and data types of a query, table or view

Is there a PostgreSQL query or command that returns the field names and field types of a query, table or view? E.g., a solution if applied to simple SELECT query like SELECT * from person should ...
18
votes
2answers
9k views

“Recheck Cond:” line in query plans with a bitmap index scan

This is a spin-off from comments to the previous question: Postgres 9.4.4 query takes forever Using PostgreSQL 9.4, there always seems to be a Recheck Cond: line after bitmap index scans in query ...
18
votes
1answer
24k views

ERROR: database “dbname” does not exist

According to the documentation, so long as I'm not connected to a database, I can either delete a database in the console using: DROP DATABASE dbname; Or I can drop it using the wrapper tool dropdb. ...
18
votes
3answers
37k views

Can I provide a default for a left outer join?

Suppose I have tables a (with column a1) and b (with columns b1 and b2) and I perform a left outer join SELECT * FROM a LEFT OUTER JOIN b ON a.a1 = b.b1 Then b1 and b2 will be NULL where a value of ...
18
votes
2answers
11k views

Trigger: move deleted rows to archive table

I have a small (~10 rows) table called restrictions in my PostgreSQL database, where values are deleted and inserted on a daily basis. I would like to have a table called restrictions_deleted, where ...