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Postgresql querying trends

Firstly apologies if this is a duplicate, I am fairly new to SQL and so Im not sure what the correct terminology to use in my searches So I have a database which records motor races, with the ...
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Set field values to newly imported rows in PostgreSQL table with existing data

I have a PostgreSQL table with existing data, and needs to import all the rows in a CSV file into that table. I am using pgadmin3's Import tool to do the import. Question: For the newly imported ...
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Inner join using an array column

Having trouble indexing and executing a query in O (log n) time. The query includes an INNER JOIN, an ORDER BY, and an equality operation. If I understand the laws of databases correctly, a query can ...
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How to execute a non-table-locking update operation on PostgreSQL? [closed]

Looking for a good way to update the value on a column for all the rows in a database (not huge, but big enough - about 10M records), without locking the whole table, so operations can continue while ...
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598 views

Most efficient to prevent duplicates

I'm building an application that will fetch messages with JSON every once in a while and store these in a postgres db. Now I want to prevent duplicates, so I calculate the sha-512 of the message and ...
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114 views

Big jump in search time for Postgres Index query for results with high selectivity

I am doing some performance comparison of databases and lucene for full-text searching. So I use Postgres to create an Index for the data to search: CREATE INDEX bodies_index ON bodies USING gin ...
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1answer
2k views

Limiting number of results in a Partition using OVER(PARTITION BY)

In the following query, why is it that we have to limit the results returned from each Partition by using the clause WHERE foo.row_num < 3 outside of the subquery foo but not from within the ...
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75 views

Very fast replication

I used this guide to make replication between my two db servers : http://wiki.postgresql.org/wiki/Streaming_Replication But, when I updated a row on master server it will be available in slave ...
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which postgres do i have installed? what directory needs to be in my path to run initdb?

I need to use postgresql with ruby on rails. I have these directories /Library/PostgreSQL and /usr/local/Cellar/postgresql/usr:local:Cellar:postgresql:9.2.2 This 2nd directory name is ...
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940 views

Getting error while importing large data through csv

I am new Postgres. I am getting constraint violation errors while importing a large CSV file. I want to disable all of the database constraints temporarily - I do not know how to do this.
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How to use array variable in query in PostgreSQL

Create table t1 ( xcheck varchar[], name text ); CREATE OR REPLACE FUNCTION fn_acgroup(xch varchar[]) RETURNS record AS DECLARE xrc as record; execute 'select name from t1 where xcheck @> ...
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Can pg_hba.conf trust processes?

Is it possible to configure PostgreSQL such that it can trust a single process, instead of a specific user?
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Postgres: Use result of group by as column names

I have a messages table in a database, which include a sender id and a message type (and of course many more columns not relevant for this question). I try to create a query which counts how many ...
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1answer
62 views

What is the algorithmic complexity of a PosgtreSQL greater than or lesser than index query (compared to equality)?

Assuming there is an index idx_int on an int_col column, what is the algorithmic complexity of a query like this? SELECT id FROM table WHERE table.int_col > 1; I'm specifically interested in ...
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5k views

Using MongoDB and PostgreSQL together

My current project is essentially a run of the mill document management system. That said, there are some wrinkles (surprise, surprise). While some of the wrinkles are fairly specific to the ...
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524 views

How does PostgreSQL physically order new records on disk (after a cluster on primary key)?

Need to know how PostgreSQL orders records on disk. In this case, I would like to take advantage of index combination as stated in the docs, which as I understand uses bitmaps to get matching rows ...
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1answer
673 views

Passing argument in trigger dynamically

CREATE TRIGGER audit_proc_tr AFTER INSERT OR UPDATE OR DELETE ON "log".hi FOR EACH ROW EXECUTE PROCEDURE "log".audit_proc(argument); CREATE OR REPLACE FUNCTION ...
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1answer
130 views

Postgres caching and bytea

I have a DB which, among other things, stores images (as bytea, if that's interesting). It also stores users' metadata, activity logs, etc., but images currently take 500MB out of the total 600MB ...
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1answer
351 views

REST webservice as a Foreign Data Wrapper in postgresql

I know it's possible to embed data from a foreign resource in a postgresql database as a foreign table and have seen examples including redis, another postgres database, etc but I can't really find ...
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How to make postgresql SUM to be more accurate on large amount of floating point data?

I'm trying to SUM 8 million floating point (REAL) values with simple query like this: SELECT SUM(metric) FROM metrics; However, it returns very inaccurate result. It should return 137,586.77, but ...
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PostgreSQL : Londiste issue

I am new to Londiste, And I want to install Londiste, accroding the Londiste Tutorial after I intall skytool (http://pgfoundry.org/frs/?group_id=1000206) , I can not find the pgqadm.py script , ...
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1answer
397 views

Inheritance and its alternatives in PostgreSQL

I make an archaeological database in PostgreSQL 9.2. The description of archaeological context has a subdivision between different types of context. I'm not sure how to implement it: 1) to violate ...
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2answers
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Postgres RIGHT JOIN with custom array

I'm using Postgres 9.1 and want to get a result with some blanks where there is no data. My query looks like the following: SELECT institution_id FROM ... WHERE institution_id IN (1, 3, 4, 5, 7, 9) ...
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4k views

Error: set_valued function called in context that cannot accept a set. What is it about?

I use Postgresql 9.1, with ubuntu 12.04. Inspired by Craig's answer to my question Concatenation of setof type or setof record I thought I would go well with using return query, setof record, and a ...
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How to turn the foreign key constraints on and off while db restore in postgres? [closed]

After using below the backup cmd in a db with 250+ tables: pg_dump -h localhost -p portNum -U userName -f fileName -o dbName I tried restoring it with the following command: psql -h localhost -p ...
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2k views

Concatenation of setof type or setof record

I use Postgresql 9.1 with Ubuntu 12.04. In a plpgsql function I try to concatenate setof type returned from another function. the type pair_id_value in question is created with create type ...
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190 views

Postgres continuous backups - should WAL numbers be sequential after pg_start_backup call?

I'm using PostgreSQL WAL archiving and pg_start_backup as outlined in the Continuous Archiving section of the Postgres manual to backup a large database. Twice a month we do a full backup and every ...
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1answer
999 views

How to access the number of rows accumulated by RETURNs in PL/pgSQL

When performing RETURN QUERY ... in a PL/pgSQL function, is it possible afterwards to directly access the number of rows accumulated into the pile of records, which are returned when the function ...
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507 views

Monitoring real-time statistics on PostgreSQL

I need to monitor the DB performance on a distributed system with multiple databases. Some of the database servers use pgbouncer to pool connections and in those servers I can connect to pgbouncer and ...
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2answers
886 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 ...
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42 views

Special syntax sth.name() in the CREATE FUNCTION statement, what does it mean?

In this SO question about stored procedures in plpgsql, the stored procedure look like sth.name(). I don't know what is the meaning of the prefix sth. For example: create or replace function ...
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2k views

Correct use of VOLATILE COST (and ROWS) indications in Postgresql stored procedure

While looking at several examples of pl/python and pl/pgsql, I have seen many - but not all - using volatile cost. ie: CREATE OR REPLACE FUNCTION my_function() RETURNS setof record AS $BODY$ -- ...
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PostgreSQL CREATE EXTENSION file not found error on Mac OS

On PostgreSQL 9.2.3 when trying this: CREATE EXTENSION btree_gist; I get this error: ERROR: could not open extension control file "/opt/local/share/postgresql92/extension/btree_gist.control": ...
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163 views

Postgresql query speed

This is my first time seriously attempting to get into the guts of the speed of a query on Postgres, and I was hoping for some more explanation of exactly what is going on. I am using Postgres v 9.1 ...
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1answer
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PostgreSQL EXCLUDE USING error: Data type integer has no default operator class

In PostgreSQL 9.2.3 I am trying to create this simplified table: CREATE TABLE test ( user_id INTEGER, startend TSTZRANGE, EXCLUDE USING gist (user_id WITH =, startend WITH &&) ); ...
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1answer
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Cannot `create function` in plpython3u, permission denied

As postgres user, I have create extension plpython3u; in my database then I have set the plpython3u to trusted: select lanpltrusted from pg_language where lanname like 'plpython3u'; returns true but ...
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Achieve PostgreSQL hstore functionality in MySQL

Please suggest any MySQL 5.5+ Engine that can support collection of key-value pairs be stored in any column of a table. I don't know if this feature is available out of the box in MySQL like ...
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2answers
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postgres backup / restore: restored database much smaller?

I am worried that my restored database is very different from the original: #check size of postgres database postgres@db1:/tmp$ psql -c "select pg_size_pretty(pg_database_size('test_db'));" ...
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1answer
621 views

Cannot use python3 as stored procedure language in posgresql database

I want to have python3 in my postgresql database for writing stored procedures. Being in the psql client, when I enter the command create extension plpython3u I get the error: couldn't open ...
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1answer
77 views

Does avg_query for PgBouncer include update and inserts?

Trying to tune our application and would like to know if the stats data that pgBouncer shows as avg_query, according to the PgBouncer docs on usage: avg_query Average query duration in ...
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2answers
3k views

Recursive query using plpgsql

I'm trying to write a plpgsql function that recursively returns a set of columns from records in a tree structure. I have a data table and a table to link the data together: DATATABLE ----------- id ...
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2answers
661 views

pessimistic locking and client death

We are considering pessimistic locking for our project (SELECT ... FOR UPDATE); as we are used to optimistic locking, we are afraid about the operation of the server being blocked on such a lock (lock ...
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548 views

Log statements from within triggers in Postgresql

I have several sql statements running in some of my plpgsql triggers. I've enabled logging with the log_statement = 'all'. It logs the 'triggering statement', but not the statements within the query ...
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2answers
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Will table inheritance in PostgreSql suit this situation?

Let's start off by saying, I'm new to PSQL and coming from a MSSQL background. I'm starting to design a DB in PSQL. So my main aim is to have a Main schema in this DB, which I am going to use to ...
3
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1answer
119 views

PostgresSQL: Get single attribute of UDT in SELECT statement

I created a user-defined type in a PostgreSQL 9.2 database and am trying in the SELECT statement to get only an attribute of the UDT. However, I don't seem to get my code to work. Creation of type ...
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456 views

A stored procedure to bulk load in Postgres or Oracle given a URL [closed]

Is there a stored procedure available in Postgres or Oracle that does a bulk load given a URL, as in: url_bulkload csvFile.ctl Where csvFile.ctl is # # csvFile.ctl -- Control file to load CSV ...
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1answer
248 views

Avoiding repetition without creating a view

Suppose that I have a query Q1 and I need to run a query like the following: Q1 union select * from (some query that uses Q1 outcome) I would like to do that: Without creating any view Without ...
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1answer
2k views

Create log file only for my executed queries

I have been using the following to set up the log file: log_statement='all', log_collector='on', log_destination='on', log_filename='filename' After that, for testing I just executed a query ...
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1answer
329 views

How to Model / Quickly test for set membership in SQL?

Each row in a table needs to be protected a list of application specific roles lets say something that looks like this example below Desired Table Structure pkey | data | roles ...
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150 views

clusterdb stopped working for PostgreSQL database in Ubuntu 12.04 server

After a fresh PostgreSQL install (version 9.2) on my Ubuntu server 12.04, clusterdb utility stopped working. I used the same config files as I used with version 9.1. Below is the actual command: ...