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Is there a way to store a PostgreSQL database directly on a block device (not filesystem)?

I am reading about where PostgreSQL stores its data it needs to offer me its service (here: http://www.postgresql.org/docs/8.4/static/storage-file-layout.html ) As it is writen there PostgreSQL's ...
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0answers
217 views

Postgres advisory lock deadlocks itself?

I am executing pg_advisory_locks using the following set of statements: SELECT pg_advisory_lock(317,2); UPDATE posts SET dislikers = array_remove(dislikers, 7) WHERE id = 317; update posts set ...
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1answer
1k views

Left outer join not returning all rows in a grouping query

I'm trying to query all users to find the price of orders in the last month. I'm doing this on PostgreSQL. Here's a toy database to show my problem: I have a people table and an orders table. I'm ...
2
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1answer
224 views

PostgreSQL return second 'Group' as an array

I have some tables that include websites and visitors and I am trying to write a query that produces a 'top 10' for each site, the tables look something like this... websites ------- website_id (pk) ...
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1answer
290 views

Linking first and second level composite primary keys

I am trying to create a new database with a hierarchical structure of two many-to-many tables using composite keys. Unfortunately the creation of tables fails stating that the foreign keys do not ...
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2answers
1k views

Is there a faster way to get UNION ALL behavior in Postgres?

I have a table (t0), in my Postgres DB, with data that looks something like this: t1_id t2_id 1 1 2 1 2 1 4 null 4 null 5 null And I have a query to return my ...
0
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1answer
173 views

How to order by Levenshtein distance?

I want to order a table according to a char field using Levenshtein distance or similar because some entries may contain underscores or grammar errors. It is a table with all the books I plan to read ...
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1answer
439 views

Duplicate records on joining

I have two tables books and books_data. books can have multiple books_data, books_data can have only one book. books_data table has date column by which I want to sort the books table. When trying to ...
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0answers
464 views

How to select column names that contains specific value from other table's column

Suppose I have table items and logs. Both tables have col1, col2, col3, col4... col(n). col1.. col(n) in table items simply specifies key name (col1 = "beef", col2 = "chicken", col3 = "bacon") ...
2
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1answer
104 views

ORA-00937 when calculating a sub-value in an aggregate select statement

The problem described below applies to Oracle 11g databases. I also tested the statements on MySQL and PostgreSQL with no problems of the kind mentioned in this question. I want to use an ...
0
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2answers
125 views

Best way to update the content of large lookups tables

In our application we have a about 20 tables that contain lookup information (read only data that the application doesn't modify). Nightly we'd like to update this information by deleting all the ...
2
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1answer
202 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, ...
1
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1answer
642 views

PostgreSQL 9.3 Amazon RDS gives error while using UUID-OSSP extension for generating uuid

I have created DB instance on RDS and used below function it gaves error while with same postgreSQL version on local development machine works fine. create or replace function uuid() returns uuid as ...
2
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2answers
331 views

Updating every cell of of a table?

I have a table with m columns and n rows. The ETL tools I was using wrote an empty ('') to every cell without a value and I would like them to be NULL instead. This got me thinking if it would be ...
1
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1answer
1k views

Change existing column in PG to auto-incremental primary key

I have a database in Postgresql, which was migrated from SQL Server (only data). On SQL Server, a table from this database has these columns: measure_id datum measure where measure_id is ...
2
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1answer
56 views

(How) can I return the most specific row on a join?

I'm trying to work out a query that can parse through a table of prices (and exceptions to those prices) to yield the applicable price for a product, ideally using a join. I'm on PostgreSQL. For ...
2
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1answer
297 views

Postgres query plans and tuning parameters

I have a query for which the explain plan indicates that the cost for using a seq scan is lower than the cost for using an index that I have set up. However the actual time for the query is 20 times ...
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1answer
110 views

Getting rid of partitioning in Postgresql 9

it turns out that our approach with list partitioning was not the best idea. We have way to much small partitions and a lot of time is wasted on partition choosing by query optimizer. What's the ...
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1answer
2k views

Use if exists in postgresql [closed]

I know about the exists feature, but that does not help me with the given situation. What I want is: Check if some row exists, and if exists then check for an another row if row exists. Here's ...
2
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1answer
100 views

Postgresql: How do full_page_writes help prevent data loss?

From the postgresql docs [full page writes are] needed because a page write that is in process during an operating system crash might be only partially completed, leading to an on-disk page that ...
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0answers
134 views

How to deal with finding nearby locations when given a zip code or city?

I am using PostgreSQL and PostGIS for this. I have downloaded dumps from Geoname, and built my tables from allCountries, alternateNames, and countryInfo. I've created my PostGIS geometry column, and ...
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0answers
54 views

SQL JOIN excluding duplicate

I'm using PostgreSQL under ubuntu 14.04. I have two tables as below: create table material_base_name ( id bigserial, base_name varchar(50), constraint pk_materials_base_name primary key (id) ); ...
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1answer
46 views

joins with “could be blank” conditions

Question is most probably stupid but I am stuck on this and cant think anymore(Pissed Off). I have these tables-> employee(has a column foreign to location),location and location_flag. And I need ...
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1answer
2k 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 ...
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0answers
127 views

postgres: access to schema objects within a function

Here's my problem: I have Schema A, owned by User 1, that owns all objects. I've created schema B, owned by User 2. I have granted User 2 all privileges to the objects owned by User 1. When logged ...
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1answer
206 views

Removing a Key From HSTORE in Postgresql

At the moment I have an hstore that describes the properties of various items. When searching I need to remove values that are unique to a each item (such as serial number, vin, and so on). According ...
0
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1answer
282 views

When is the postgres auto vacuum executed

I am using an older version of postgres(8.4.20). I know that the auto vaccum process is executed frequently to free disk space of queries that deleted or updated data in tables. I have a database ...
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3answers
134 views

Longest matching suffix while using aggregate functions

Background Looking to find the longest matching string suffix. Setup Consider the following fiddle: CREATE TABLE noun ("label" varchar(10)) ; INSERT INTO noun ("label") VALUES ...
2
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2answers
132 views

Tables names in a supertype/subtype schema [closed]

I have 3 types of users in my app. The users share some common attributes, but they also have quite a bit of stuff that pertains uniquely to each user type. I have a person table that contains limited ...
1
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2answers
518 views

SET ROLE via parameterized query

In the very helpful response I received to a previous question, I am trying to write some JDBC code that first sets the role to a specific user before executing subsequent queries. On the safe side I ...
1
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1answer
217 views

Upgrading 8.1 to 9.3 - using statement log and WAL to check compatibility?

We're migrating from postgres 8.1 to 9.3, since we need streaming replication badly. All the application developers have deserted the company a long time ago, way before my time here, so there is ...
0
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1answer
56 views

Check for blocked queries periodically and cancel them

I have series of update queries which are executed every 5-10 seconds. Sometimes it happens that one of these will block all the pending update queries as for some reason it just freezes. Since I can ...
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2answers
356 views

PostgreSQL : dependencies on a schema

I need to delete a schema in my PostgreSQL database. I would like to make sure that the schema is not used in another schema (for instance : this schema is used for a view in another one). Is there a ...
3
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1answer
241 views

Unsupported languages in Postgres Full text search

My web application supports 3 languages, English, Traditional Chinese, Vietnamese. I understand that Traditional Chinese and Vietnamese is not supported in Postgres' Full Text Search. If I were to go ...
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2answers
142 views

pg_stat_activity entries with no corresponding process on the client

If I see an entry in pg_stat_activity for a client_addr:client_port combination where there is no process bound to that port on the indicated client, what does that mean? Just that the client process ...
0
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2answers
889 views

Postgresql. Generate sets of random integers

With this command I can generate 16384 random integers between 1 AND 200,000. SELECT generate_series (1,16384),(random()*200000)::int AS id I want to generate 10 sets of such integers. Each set ...
3
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1answer
623 views

PostgreSQL Common Table Expressions vs a temporary table?

The PostgreSQL documentation on WITH shows the following example: WITH regional_sales AS ( SELECT region, SUM(amount) AS total_sales FROM orders GROUP BY region ), ...
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2answers
4k 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 ...
0
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2answers
808 views

Postgres: error message “does not exist” when dropping existing trigger

I have a trigger associated to a table. When i drop it via DROP TRIGGER IF EXISTS myTrigger on dummytable; postgres tells me NOTICE: trigger "mytrigger" for table "dummytable" does not ...
2
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3answers
204 views

Can I perform a MAX over a pair of columns?

I would like to execute the following: SELECT person, MAX( (date, priority) ) FROM table GROUP BY person; It would return a person, date and priority row for each distinct value in the person ...
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3answers
2k views

Slow queries on billions-rows-table // index used

Since I'm a young developer and not really skilled in using databases (PostgreSQL 9.3) I ran into some problems with a project, where I really need help with. My project is about collecting data of ...
4
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1answer
144 views

PL/pgSQL - Indexes vs Collation vs Pattern Ops

I'm using PostgreSQL 9.3. Having already read articles and answers on DBA stackexchange: Why would you index text pattern ops on a text column PostgreSQL documentation: Indexes - Opclass Pattern ...
4
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1answer
62 views

Checking for multiple identical values in a Posgresql array

I have a simple table in Postgresql: CREATE TABLE data (id integer, values integer[]); INSERT INTO data VALUES (1, '{1,2,3,4,5}'); INSERT INTO data VALUES (2, '{1,1,2,3,4,5}'); INSERT INTO data ...
1
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1answer
603 views

Problem with LISTEN - NOTIFY mechanism in PostgreSQL

I'm struggling with PostgreSQL LISTEN - NOTIFY mechanism. I open two consoles and connect to my database using psql client: psql -U postgres test_db In the first console I subscribe to some ...
3
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1answer
384 views

PostgreSQL server problem in Windows XP

2014-10-01 09:22:49 IST LOG: database system was interrupted; last known up at 2014-09-30 18:30:24 IST 2014-10-01 09:22:49 IST FATAL: the database system is starting up 2014-10-01 09:22:49 IST LOG: ...
1
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0answers
116 views

Select all foreign key relationship chains from any set of potentially gapped table names

I am using this query to find all foreign key relationships: SELECT con.relname AS child_table, att2.attname AS child_column, cl.relname AS parent_table, att.attname AS parent_column ...
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1answer
28 views

Getting information on users payments via subscriptions

My current table db design looks like this : - User has one subscription - One subscription has many payments Table subscription has a user_id, which is FK to user table. Table payment has a ...
3
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2answers
248 views

How to save an interval of years in postgresql

I have to save an interval of years, like: id intervalYears 1 2014/2015 2 2015/2016 3 2016/2017 And so on. Those years are like accademic years, so the first year must be lesser then the second, ...
1
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1answer
561 views

use variable to determine the name of a column in the select in postgre

I'm trying create a update for a new structure of tables from a old table, but not using functions. I'm trying create a script to it. The old table is like this: -- old table (OldTable) name| col_a | ...
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2answers
419 views

Importing CSV into multiple tables using PostgreSQL

I have a very big CSV file with the following format: TAG,TIME,VALUE as an example row: footag,2014-06-25 08:00:00.0,3400.0 I used to import it easily inside PostgreSQL 9.3 using the following: ...