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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Sharding Postgres Database

I have a Postgres database that has grown to the size where it is no longer feasible to store everything on a single database node. There is a Customer table in my schema where each row represents a ...
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insert inserted id to another table

Here's the scenario: create table a ( id serial primary key, val text ); create table b ( id serial primary key, a_id integer references a(id) ); create rule a_inserted as on insert to a do ...
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Are CTEs multithreaded?

Here and here seem to suggest that they are, but I've also been told (source unlocatable) that a multi-row single-statement insert will only use one thread for all writing, that to multithread it, the ...
1
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1answer
24 views

Performance of single vs multiple column unique constraint

I'm using PostgreSQL 9.3. I want to understand if I have an option to make a constraint unique across the entire table vs. unique across a subset of the table (i.e. by using 2 columns in the unique ...
1
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1answer
19 views

Table-based custom type does not verify check constraints

Is there any way for a table-based custom type to obey the table check constraints, other than creating my own type based on the table? Assume the following table that serves as a source for the ...
2
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1answer
43 views

Monitoring the Postgres query parser

As I understand it, when you send a query to Postgres like: SELECT id FROM table1 WHERE name = $1; Postgres will create a query plan. The plan will be cached for the same query in the same ...
3
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1answer
2k views

How to remove known elements from a JSON[] array in PostgreSQL?

I'm facing an issue regarding using the JSON data type in PostgreSQL. I try to achieve storing a Java model denormalized in the DB. The model features lists of complex objects. Thus, I decided to ...
0
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0answers
18 views

Get columns from NEW when execute update on postgresql [on hold]

I need know if determide fields are into result of update execution, e.g. IF NEW.niveope is null THEN _new_nivope := 0; ELSE _new_nivope := NEW.nivope; END IF; When I execute: EXPLAIN ...
2
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1answer
30 views

Get products of category plus all child categories till leaf nodes

We have a hierarchy which looks this: Now the problem is that most products are only connected with 1 category, which is most of the time the lowest level. I am trying to get ALL products below a ...
1
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1answer
330 views

Upgrading using pg_upgrade on windows fails

When upgrading from postgres 9.2 to 9.3 by following the upgrade procedure found in PostgreSQL 9.3.4 documentation about pg_upgrade, the following command fails: RUNAS /USER:postgres "CMD.EXE" ...
2
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1answer
64 views

Recursive CTE to find unique slug

I have an article table where I want the slug to be unique. CREATE TABLE article ( title char(50) NOT NULL, slug char(50) NOT NULL ); When the user enters a title e.g. News on Apple, I want ...
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1answer
22 views

How can I create a bool column for a view based on the result of a statement?

I'm using PostgreSQL as my database. CREATE TABLE groups ( id SERIAL NOT NULL, name TEXT NOT NULL, PRIMARY KEY (id), UNIQUE (name) ); CREATE TABLE users ( id ...
3
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2answers
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Query planner thinks doing a sequential scan on a very large table is faster than using an index?

I've got a query that selects the most favorited photo for each of the last 12 editions for a particular domain (this is just a segment of a larger query, but the problem seems to stem from here): ...
3
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1answer
158 views

Add NOT NULL constraint to large table without table scan

Trying to add a NOT NULL constraint to a table with 1 billion rows. I cannot afford a table lock for more than a couple of seconds. Is there a way to prevent a full table scan during the alter table ...
0
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1answer
403 views

pgpool-II configuring multiple master databases

I could not find a solution for this anywhere, not even in the pgpool manuals. How do I configure multiple - master postgresql databases with pgpool-II? Additional requirement is that each master ...
0
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1answer
34 views

Postgresql csv to db translate foreign keys

I'm trying to import data from a csv to a postgresql database. the db table looks like this: CREATE TABLE texts( text_id serial PRIMARY KEY, topic_id integer REFERENCES topics, format_id integer ...
2
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1answer
86 views

SELECT query with DISTINCT on a table-structure for graphs is very slow

I have 2 tables where nodes contains about 60m rows and edges about 500m rows (both growing fast). These two tables represent a directed graph. CREATE TABLE edges ( node_from bigint NOT NULL, ...
3
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1answer
34 views

Possible reasons for irregularly high query execution time?

The above is a graph showing the average response times per second (including error bars) for an experiment where I simulate 30 clients which are all invoking the same query multiple times. I ran ...
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0answers
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Are A or D series VMs better for deploying PostgreSQL on Azure?

In Azure there are VMs that have local storage either as spinning disk (A-series) or SSD (D-series). Considering this space is wiped on reboot... Is there a benefit to choosing the SSD option for ...
1
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1answer
19 views

How do I use pg_dump and pg_restore to move a large database to another machine?

I'm a bit unclear on how to use the pg_dump/pg_restore duo to move a large-ish database. Here is the command I use to dump the database (the host and username are taken from environmental variables): ...
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2answers
38 views

Group by range of years

I've got a big table (~9M rows) and want to group the rows on a field containing the year. So far that's pretty easy: // greatly simplified: SELECT count(*), year FROM dataset GROUP BY year ORDER BY ...
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0answers
22 views

We are trying to set up a database to be able to read and write messages on a website [on hold]

We are trying to set up a database to be able to read and write messages on a website but cannot figure out how to make a function for a button to take the information from the webpage text box and ...
2
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0answers
59 views

Prepared statement overhead

I am using libpqxx to communicate with a PostgreSQL 9.3 server. For multiple table inserts, if they are split into individual prepared statements, they cost approximately 2ms each. If they are all ...
1
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1answer
117 views

Should one always VACUUM ANALYZE before REINDEXing in PostgreSQL 8.4?

Early in the morning every day a pgAgent job refreshes the contents of table A from table B on my PostgreSQL 8.4 database. Table A contains around 140k records across 91 columns and has two indexes - ...
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PostgreSQL: PANIC: heap2_redo: unknown op code 32

I was doing migrations while the server was still accessing the slave DB. I have a master / slave setup. After I restarted the server, I realized I couldn't connect to the SLAVE anymore. I went into ...
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21 views

ETL - Moving data from Postgres/Oracle to a TripleStore (RDF)

I'm looking for pointers on how to handle an ETL process that I have to implement for my organization. I know how to query SQL database but i'm not SQL DB specialist. I work more in the sphere of the ...
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0answers
38 views

Unique index on columns which are allowed to be NULL

I'm having a little problem right now, we use this table in our database: CREATE TABLE offer ( offer_id serial PRIMARY KEY , product_id int NOT NULL REFERENCES product , price_old ...
5
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2answers
134 views

Managing CTE execution order under uncertainty

I am writing a large, multi-step CTE for performance reasons. In one query, data must be moved from one table to another, but the quantity of rows moved is uncertain and could be zero. In a ...
5
votes
1answer
491 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 ...
2
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2answers
27 views

Get all (non repeated) distribuidores with their paises given a producto_solicitud

I have this schema: And as title says I need to get all records from fabricante_distribuidor by given producto_solicitud.id value. I'm doing in this way: SELECT ...
0
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1answer
1k views

postgres service suddenly not working after the computer crashed while working

I've been working with postgres on a linux server for the last couple of months. Last week, half of our servers crashed and my one with them. I was in the middle of uploading data to the postgres ...
0
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1answer
22 views

Initialize, Start Server and Create Database in Single Script

I am writing a provision script for a dev environment with the following: sudo su - postgres <<EOF cd ~/data pg_ctl -D . initdb pg_ctl -D . -l run.log start createdb mydb pg_ctl -D . stop EOF ...
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1answer
26 views

How to update values from bytea to varchar in Greenplum?

I need to convert hexa to values and need to update the values in a varchar field, I have tried: select pg_catalog.decode(column,'hex') The above code converted hexa to values but when I try to ...
5
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1answer
67 views

Sort by number of related rows in referencing table

Let there be two tables: Users id [pk] | name --------+--------- 1 | Alice 2 | Bob 3 | Charlie 4 | Dan Emails id | user_id | email ----+---------+------- 1 | 1 ...
0
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1answer
14 views

create insertion rule on view returning id

I have a table private.products and a view public.products representing that table. And I want to create entries in private.products while inserting into view, it all works right, except that I also ...
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0answers
25 views

How to Insert records from remote database to local database using dblink in postgresql 9.3

I have a scenario like i have a two DB, one resides in remote server and other resides local. Now i have to fetch the records from remote DB when new records are inserted on tables (in remote DB) and ...
0
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1answer
226 views

Taking hot backup of slave node in postgres (master-slave config with repmgr)

I have a postgresql setup with master-slave configuration using repmgr. I'm struggling with taking a consistent snapshot backup (pg_start_backup) of the slave node, this is due the fact that the slave ...
4
votes
2answers
927 views

Postgres log files not rotating

I have a postgres system with a hot standby server. They use the same config file. I've setup the log rotation to use log_rotation_size and log_rotation_age so that the master server is rotated every ...
0
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1answer
302 views

Sync offline PostgreSQL server

I am new to PostgreSQL. I am looking for a solution wherein 2 mirror images of a database sit on a local and remote server. All the work is done on the local server and at periodically synced with the ...
7
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2answers
843 views

Migrate heroku database to Amazon RDS with minimum downtime

I have a heroku postgres database and want to migrate it to Amazon RDS to save cost. What's a way to do so with minimum downtime? Usually this involves replicating database in real time and then ...
1
vote
1answer
131 views

PostgreSQL's Query Hierarchical data poor performance

Badly need some technical assistance on this query performance issue I'm working on. Summary of the data structure is: 1 project has many homeprofiles, 1 homeprofile has many tasks, 1 task has many ...
0
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1answer
101 views

Error: /var/lib/postgresql/9.3/main is not accessible or does not exist

I have a PostgreSQL db that was running on my server. I tried to do a db_dump and got a weird error message. I eventually thought I would just restart PostgreSQL. However its now stopped and won't ...
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1answer
30 views

What are the side-effects of disabling nested loops in postgres?

A query of multiple joins spends a lot of time on nested loops. I disabled the nested loops and the query ran much faster. However, I have been told that nested loops might give me wrong results by ...
3
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2answers
27 views

How can I determine if a table exists in the current search_path with PLPGSQL?

I'm writing a setup script for an application that's an addon for another application, so I want to check if the tables for the other application exist. If not, I want to give the user a useful ...
2
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1answer
45 views
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0answers
13 views

How to do a pgdump with strings encoded?

When I perform a dump with pg_dump tool, with a "flat" sql format, pg_dump create a regular sql file but the restoration with pg_restore fails because the strings are not escaped. For example, single ...
1
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1answer
41 views

Migrate SQL Server binary datadump to postgresql

I just got a very big dataset (+/-55GB) in a binary SQL Server format. Is there an easy way to import this file into a Postgresql Server? I found some converter-programs, but they 'only' convert ...
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2answers
42 views

Add function parameter to SQL query WHERE clause

I have a web application in java and it uses a query. I don't want to write the query into Java, so I made a function: CREATE OR REPLACE FUNCTION testFunc(inputs text) RETURNS TABLE(...) AS $$ ...
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0answers
36 views

Translate psql meta-command to SQL

How can I translate a psql meta-command (like \dt or \ds) to the equivalent SQL query? I found some of the translations here. But it would be nice to have a command to do it automatically.
0
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1answer
841 views

What is best strategy for backup on streaming replication(hot standby) environment

I have questions. What is best strategy for backup on streaming replication(hot standby) environment. I’d like to do backup on slave server and restore(PITR). First, I set up streaming ...