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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Non-sequential Primary Key performance in PostgreSQL 9.3

Due to requirement to support distributed environment, each of my clients has been assigned unique node id, it appends the node id with running number as primary key and stores at local database. E.g. ...
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Extract timestamp from UUIDv1

Is it possible to extract timestamp from uuid version 1 in PostgreSQL? I am also curious is it possible to order by uuid's timestamp value like it's done in Cassandra's TimeUUID datatype?
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31 views

PostgreSQL SELECT primary key as serial or bigserial query review

I've meshed together a way to determine what the data_type is as in the data_type you use in the syntax when creating a new table (not the political definition) based off of the PostgreSQL wiki page ...
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Clustered index performance consideration in MySQL & PostgreSQL

In MySQL/InnoDB, the clustered index is synonymous with the primary key, so picking up a poor primary key affect your db performance, i.e. use of UUID as PK is a performance killer for database write. ...
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115 views

Schema for lists of relationship differences

Say there is a data model that allows for relationships to be defined either explicitly or as a list of records added or removed relative to some existing item: Item <–> *Properties and Item ...
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42 views

Export Postgres table as json

Is there a way to export postgres table data as json to a file? I need the output to be line by line, like: {'id':1,'name':'David'} {'id':2,'name':'James'} ... EDIT: postgres version: 9.3.4
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6 views

pg_restore certain tables only

I'm looking for a way to use pg_restore to restore a newly-created database from a dump file, but only certain tables from that file. (There are a lot of extra tables in the database that are slow to ...
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3k views

USING construct in JOIN clause can introduce optimization barriers in certain cases?

It was brought to my attention that the USING construct (instead of ON) in the FROM clause of SELECT queries might introduce optimization barriers in certain cases. I mean this key word: SELECT * ...
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1answer
21 views

Alternate per 2 postgresql rows, but start over if there are rows remaining

I'm trying to select below table, grouped by two (=max, if there is only one, show one) of each supplier_id. But, after all suppliers are selected it needs to start over. So this is the table: Table: ...
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1answer
596 views

Configuring Postgres 9.2 streaming replication with Redhat Clustering Suite for High Availability

I'm in the process of configuring postgresql 9.2 streaming replication with Redhat Clustering Suite for high availability. I have 1 master and 1 hot standby configured to replicate the data from ...
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2answers
69 views

How to do an =ANY(SELECT…query in postgresql?

I'm trying to select all the latitudes and longitudes for a group of users based on their id being in an array stored in another table. Here's my attempt: SELECT latitude, longitude FROM userloc ...
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3answers
7k views

Connecting pgAdmin3 to Postgres on Heroku

I'm running a Heroku Postgres database (Database) in assosciation with a Django app. The docs that refer to the add-on are here. I thought this would be a worthwhile question for the community ...
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1answer
28 views

How to enforce an “exactly-one-per-group” constraint?

I have a table x that I've defined like this: CREATE TABLE x ( xid INTEGER NOT NULL PRIMARY KEY, yid INTEGER NOT NULL REFERENCES y(yid), is_principal BOOLEAN NOT NULL ); This definition ...
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1answer
39 views

Maximum sum() of overlapping ranges

Essentially my question is: how does one do aggregate operations involving overlapping ranges in PostgreSQL 9.3 (or 9.4)? The specific problem I have at hand is that given a range, I want to find the ...
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3answers
56 views

Slow query when adding additional where clause

Here's my setup (Postgres 9.3) Posts project_id Messages post_id kind updated_at I'm trying to get the most recently updated 100 messages that belong to posts (on a specific project) that are ...
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1answer
630 views

How to add FK on a column of composite type in PostgreSQL?

I have a table which contains a composite type and I am trying to connect a column of it to another table's PK. CREATE TABLE aaa (col1 SERIAL PRIMARY KEY); CREATE TYPE bbb AS (col2 INTEGER); CREATE ...
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2answers
2k views

How do I determine if a column is defined as a serial data type instead of an integer based off the catalog?

So I'm currently creating some SQL to read through the postgres (9.1) catalogs to build table definitions. However, I am encountering a problem with SERIAL/BIGSERIAL data types. Example: CREATE ...
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33 views

Is it bad practice to launch more than 100 sql statements at once?

I have PHP code that is meant to updating the billing status of someone. I only want it to update if the bill has been successfully created and therefore I think a possible solution would be to ...
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1answer
20 views

How to view full blocking postgres queries?

I'm using a statement from this page to view blocking queries in Postgres SELECT bl.pid AS blocked_pid, a.usename AS blocked_user, ka.query ...
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1answer
45 views

Is making joins between different table spaces slower?

In MySQL and PostgreSQL, is making joins between different tablespaces inherently slower, compared to joining tables in the same tablespace?
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14 views

Rely on .pgpass in CREATE USER MAPPING

I am trying to create a script which creates a postgres-fdw connection between two postgres 9.4 databases. The script (which is checked in under version control), has been relying on pgpass to do ...
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6answers
6k views

SQL Query Formatter [on hold]

Are there any (Linux based) SQL Query Formatting programs/plugins/extensions? I use PostgreSQL and MySQL but other DB's are welcome as well. I can use a VM to test with but would prefer a Linux ...
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1answer
94 views

How to get back the PostgreSQL database to a specific poin in time?

I am running a batch script(10:40) in postgresql database which will insert values in differnt tables on postgresql till (11:00).Later i came to know that the script was executed mistakenly.Now how ...
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1answer
75 views

How can I identify queries that are producing cache misses in Postgres?

I have a Postgres database with a total data size of 115GB. The server has ~60GB of memory. The index cache hit rate is holding at 99%+ but the table cache hit rate has fallen to ~97%. I am trying ...
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13 views

Amazon RDS non superuser create function in C

I am asked to restore a Rails application to a postgresql RDS instance. There are many functions in C but looks like only superuser can create functions in C and I could not get superuser access on ...
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13 views

Determine existence in recursive working table

I have a query that needs to check for existence of each input row type in another table, but it is unnecessary and inefficient to check for existence of subsequent rows of the same row type if one is ...
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1answer
34 views

PostgreSQL: Foreign key on string column

I'm currently in a process of redesigning a legacy database. One of the tables primary key is a varchar(254). I need to create a table relating to it. So for example: create table "Item" ( ...
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1answer
30 views

Keep trailing zeros on Timestamp SELECT

This is the issue: I am reading rows with a timestamp column from a table and I need to make sure that the database returns the timestamp with a fixed width. But I am encountering instances where the ...
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1answer
1k views

PgPool 2 with HA Proxy

So, I'm looking to add high availability to a postgresql server. I've looked into some tutorials on the web but, haven't been able to find exactly what I'm looking for. E.g.: PostgreSQL ...
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1answer
23 views

pg_restore: [archiver (db)] could not execute query: ERROR: schema “public” already exists

I am using pg_dump / pg_restore to backup and restore a PostgreSQL database, but am getting some error messages (and a non-zero exit status) from pg_restore. I tried a super simple base case (outlined ...
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1answer
589 views

pgpool2 setup on master-slave replication using postgreql 9.1

I have already setup 2 ubuntu server 12.04 LTS on my local machine using virtual box and is using the master-slave replication (postgresql 9.1). 192.168.0.109 = master 192.168.0.110 = slave my ...
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1answer
4k views

How can I benchmark a PostgreSQL query?

I want to benchmark a query containing an user-defined function I have written for PostgreSQL. Are there any standard ways to run such a benchmark? I know that timing can be turned on with \timing ...
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2answers
51 views

Is there a way I can speed up queries against this particular view?

I have three tables in a PostgreSQL database that I'm querying via a view and some joins. CREATE TABLE network_info ( network CIDR NOT NULL, some_info TEXT NULL, ...
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29 views

(How) does table inheritance interfere with locking in postgres?

I have a table inheritance setup that might be simplified like this: CREATE TABLE p ( id BIGSERIAL PRIMARY KEY, type_id BIGINT, approved BOOLEAN ); CREATE INDEX ON p(approved); CREATE ...
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1answer
87 views

PostgreSQL replication with fsync disabled?

I need to run PostgreSQL in-memory (for performance reasons), so I intend to disable fsync, which means that no writes will be sent to the WAL. However, as part of my scheme to meet another ...
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41 views

Postgres 9.0 recovery from inadvertent drop-all-tables event

Due to a accidental config file check-in, a unit test wiped out our entire production database (did a drop, then re-created the tables). Trying to restore from backup revealed the recent backups were ...
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5 views

XRC error when trying to access PostgreSQL view properties

I have strange problem, when trying to access PostgreSQL view properties through PgAdmin III: Error: XRC error: 197: invalid row index 1: must be less than 1 After this error is displayed, I am ...
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1answer
27 views

Compare data between 2 different schemas

We refactored our old database. Some tables were dropped, some tables were split into 2 new tables etc. So now we have an absolutely new DB schema which has many differences from the old one. Someone ...
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5 views

postgres containers share pgdata mount

Due to an oversight, we have 3 postgres containers (docker) all mounting the same pgdata directory. In essence this means 3 postgres instances are running over the same pgdata. I imagine this would ...
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Delete fabricante_producto_solicitud only if is not related to modelo_marca_producto

I have this related tables: It's possible, in one query, check if fabricante_producto_solicitud has relation with modelo_marca_producto or do I need to rely on programmatic way? I need some ...
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1answer
33 views

How to select a record and update another record with selected

Say, I have a table: User User_key User_id User_name User_status State 1 001 Adam Active CA 2 002 Zack Active NY 3 003 ...
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1answer
18 views

PostgreSQL determine column type when data_type is set to ARRAY

I came across an oddity where PostgreSQL sets the data_type to ARRAY in the information_schema.columns table. I did the following query to gain some insight: SELECT * FROM information_schema.columns ...
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1answer
332 views

How can I get data from broken PostgreSQL server?

I have installed CentOS on a virtual machine and installed the latest version of PostgreSQL server 9.3. I have added PostGIS extension and some data. For some reason, the PostgreSQL service now fails ...
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2answers
5k views

psql: could not connect to server: No such file or directory

The error in its entirety reads: psql: could not connect to server: No such file or directory. Is the server running locally and accepting connections on Unix domain socket ...
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2answers
29 views

join value in a RETURNING which is not inserted

Im doing an insert from a query which joins two tables, then I want the new ID from the inserted row, and a field from the original row which is not involved in the insert.Is it possible? I get a ...
0
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1answer
316 views

pgpool2 not working on my Ubuntu i686 athlon i386 GNU/Linux

I am trying to implement replication and load balancing on my Ubuntu i686 athlon i386 GNU/Linux.for creating database clustures I have installed postgresql contrib 9.1.11 having initially database ...
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3answers
61 views

Getting around the constraint “column must appear in the GROUP BY clause or be used in an aggregate function”

I'm using Postgres, which enforces the constraint that all columns in a SELECT...GROUP BY must appear in the GROUP BY clause or be used in an aggregate function. Lets say I'm modelling peoples' cars, ...
2
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1answer
50 views

Unused index in range of dates query (PostgreSQL, timestamp with time zone)

I think maybe I am making a dumb mistake here, so apologies in advance. But I have a query that is not using existing indices and I do not understand why. Am I reading the plan wrong? Are the indices ...
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1answer
16 views

Adding column to Postgres table fails

I have a Postgres (8.4.20) table that I'm supposed to add columns to, but it seems to have some problems that I have difficulties to debug: I'm attempting what I thought was a simple ALTER TABLE... ...
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Need help on transferring data from a PostgreSQL database to a future (to be decided) database!

(English isn't my native language) I'm doing an internship for school and my task is to theoretically describe the best way to transfer the data from their current database (PostgreSQL) that they have ...