About PostgreSQL performance optimization. It is essential to include sufficient information in your question as outlined in the tag info. For simple cases and beginners questions, please ask on http://stackoverflow.com/ instead.

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Multi-core PostgreSQL server - how to improve performance [on hold]

I have a PostgreSQL 9.3.5 server with 8 CPU cores. I've noticed that adding cores to the server doesn't improve its performance. It is probably caused by the fact that Postgres doesn't support ...
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29 views

Postgres 4x Slower Than It Was

Our Postgres performance has gone down to 1/4 of what it was, and we can't figure out why. We have two machines with identical hardware (let's call them A and B): Intel(R) Xeon(R) CPU E5-4640 0 @ ...
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1answer
42 views

How to optimize the sort in Postgres query

I've been trying to optimize the sort in the following query. I ran EXPLAIN ANALYZE and the majority of the time is during the sort when it arranges the output by distance. I've tried converting the ...
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2answers
86 views

Why seq-scan can be much faster than index-scan and index-only-scan in this simple query?

I am using PostgreSQL 9.4.4. I have a query like this: SELECT COUNT(*) FROM A,B WHERE A.a = B.b a and b are the Primary Keys of tables A and B, so there are B-indexes on a & b By default, ...
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PostgreSQL/PostGIS: Query seems inordinately time-consuming

I'm doing what I would consider a pretty straightforward query on two tables that aren't huge (~626k records in one; ~47k records in the other). Both tables have GIST indices on their spatial ...
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1answer
22 views

How to Choose Between VALUES and SELECT for INSERT?

This answer raised the question for me how to choose between VALUES and SELECT in such a function . Using PostgreSQL 9.4.3 on x86_64-unknown-linux-gnu, compiled by gcc (Debian 4.9.2-10) 4.9.2, 64-bit: ...
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1answer
39 views

PostgreSQL window functions very slow on big table

I have a PostgreSQL table constructed as device_id | point | dt_edit ----------+-----------+---------- 100 | geometry | timestamp 101 | geometry | timestamp 100 | geometry | ...
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1answer
65 views

Slow window function query with big table

I'm doing some performance testing on a new DB design on PostgreSQL 9.4rc1 and I'm seeing some pretty slow queries using window functions. Here is my table setup: CREATE TABLE player_stat ( ...
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1answer
51 views

Why does it take so long for Postgres to return a sequence number?

I have an application that does bulk loads into a large table (100 million rows). I am using Postgres' COPY FROM functionality to load data from a flat file. The target table has a primary key of id. ...
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2answers
107 views

Postgres 9.4.4 query takes forever

We're running Postgres 9.4.4 on CentOS 6.5 and have a SELECT query that has worked for years, but stopped working and hangs after we upgraded from 9.2 (it took a while to notice it, so I don't know if ...
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2answers
205 views

How to speed up ORDER BY sorting when using GIN index in PostgreSQL?

I have a table like this: CREATE TABLE products ( id serial PRIMARY KEY, category_ids integer[], published boolean NOT NULL, score integer NOT NULL, title varchar NOT NULL); A product ...
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1answer
50 views

postgresql - how and why indexes are bigger than their tables

I'm using postgresql 9.3 and trying to understand how and why indexes are bigger than their tables. Sample output: database_name | database_size | table_name ...
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51 views

PostgreSQL query taking a long time

I have a query that is taking hours to run. There is a large table to parse, is there any way to optimise this? with VehData as ( SELECT * from dblink('host=databasesrv port=1234 ...
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1answer
63 views

Problem with UNION ALL

I have to process 200 points (lat, long) to calculate the minor distance of same object (street in this case). So, I made a simple query to obtain 1 result, and replicate the same to the other 199. ...
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1answer
46 views

improve long running query

I have this query INSERT INTO interactions( user_id, external_object_id, origin, interaction_type, interaction_sub_type, published_at, origin_id, created_at, updated_at) SELECT ...
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5answers
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SELECT DISTINCT on multiple columns

Supposing we have a table with four columns (a,b,c,d) of the same data type. Is it possible to select all distinct values within the data in the columns and return them as a single column or do I ...
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2answers
55 views

Speed up creation of Postgres partial index

I am trying to create partial indexes for a large (1.2TB), static table in Postgres 9.4. My data is completely static, so I am able to insert all data, then create all indexes. In this 1.2TB table, ...
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1answer
60 views

Postgres not using the index even when rows returned is 5% of the table

I have a postgres table with the following structure: +---------+-------------+-------------+----------+---------+---------+ | id | timestamp | numvalues | text1 | text2 | text3 | ...
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1answer
28 views

Spiky COMMIT results in performance slowdowns with Postgres 8.4

We just installed performance monitoring on our web application, and we're seeing a spiky pattern in response times from our Postgres 8.4 server. The spikes correspond with significant slowdown in our ...
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1answer
38 views

Optimize view (and underlying table) for averaging timestamps into hours

I have this table: CREATE TABLE spp.rtprices ( "interval" timestamp without time zone NOT NULL, rtlmp numeric(12,6), rtmcc numeric(12,6), rtmcl numeric(12,6), node_id integer NOT NULL, ...
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1answer
102 views

How to index for timestamp queries

I have a products table where I insert around 150,000 records a day. Most of them are redundant, but I need to keep them because of the new expiration date. I get product feeds from about 5 vendors a ...
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1answer
67 views

Postgresql performance issues when issuing many small inserts and updates one at a time

I have a production web server with postgresql database. My server gets data from another server every hour on the hour. The other server wakes up and sends many requests to my server, each result in ...
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2answers
190 views

Many columns vs few tables - performance wise

Yes, I am aware that data normalization should be my priority (as it is). I've got a table with 65 columns storing vehicle data with columns: used_vehicle, color, doors, mileage, price and so forth, ...
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2answers
135 views

Postgres Slow Queries - Autovacuum frequency

We've noticed the performance of our platform drop in recent weeks so I've run the following: select relname, last_vacuum, last_autovacuum, last_analyze, last_autoanalyze from pg_stat_user_tables ...
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2answers
125 views

Optimizing queries on a range of timestamps (one column)

I am using Postgres 9.3 through Heroku. I have a table, "traffic", with 1M+ records that has many inserts and updates every day. I need to perform SUM operations across this table over different time ...
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1answer
117 views

how to use index to speed up sorting in postgres

I am using postgres 9.4. The messages has the following schema: messages belongs to feed_id, and has posted_at, also messages can have a parent message (in case of replies). ...
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0answers
74 views

Query for a table with paging and filtering vs. CTE (common table expression)

Intro In PostgreSQL 9.3: I am building a query that fetches data for a table that supports sorting, filtering and paging. Think Customers for example, you want to show name, surname, some detailed ...
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3answers
132 views

Scalable query for running counts of events within x previous days

I already posted this question on stackoverflow but I thought that I might get a better answer here. I have a table storing millions of events occurring to users: ...
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2answers
58 views

Slow Select over View

My simple SELECT statement on a view in Postgres 9.3.1 is pretty slow. The receipts table has 20 million entries and the other one has around 17k. But I still think it should be faster than ~16 ...
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0answers
85 views

Slow query over 10mil rows with group by on indexed column

I've got a slow query which I want to optimize. SELECT pand.bouwjaar AS construction_date, count(*) FROM pand AS pand WHERE pand.begindatumtijdvakgeldigheid <= 'now'::text::timestamp ...
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1answer
35 views

Index for a Postgres query with a sort and an equality

This query is very slow: EXPLAIN (ANALYZE, buffers) SELECT * FROM "Follows" AS "Follow" INNER JOIN "Users" AS "followee" ON "Follow"."followeeId" = "followee"."id" WHERE "Follow"."followerId" ...
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1answer
74 views

Best query to exclude existing friends from query

I have a User table / id_user / username / .. friends table (pair AB and BA): / friend_of / friend_to and a friend_request table (used for pending friend requests) / id_req/ sent_from / sent_to ...
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1answer
42 views

Finding the current prices for n Fuelstations at a certain point in time

I have a Table where price information is stored in with approx 13 million rows stored in a PostgreSQL 9.5 database. CREATE TABLE public.de_tt_priceinfo ( id integer NOT NULL DEFAULT ...
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1answer
80 views

PostgreSQL isn't using indices in FULL OUTER JOIN

I have these tables I'd like to do a FULL OUTER JOIN between. They both have an index on (ts_minute, user_id, campaign_id, host_id) (which matches the join condition). In the following query, if I ...
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1answer
136 views

How do completely empty columns in a large table affect performance?

I have 400 million rows in a Postgres db, and the table has 18 columns: id serial NOT NULL, a integer, b integer, c integer, d smallint, e timestamp without time zone, f smallint, g timestamp without ...
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2answers
78 views

How can one optimize a query involving a sort and a LIKE?

Here is the query: EXPLAIN ANALYZE SELECT * FROM "Users" AS "User" WHERE "User"."name" LIKE 'garr%' AND "User"."id" NOT IN (2449214) AND "User"."hellbanned" IS NULL AND ...
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1answer
45 views

Does READ COMMITTED always start over after serialization failures while SERIALIZABLE simply fails?

On the PostgreSQL Concurrency With MVCC page, it says: know what you’re thinking though: what about a two transactions updating the same row at the same time? This is where transaction isolation ...
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2answers
171 views

Optimizing a Postgres query with a large IN

This query gets a list of posts created by people you follow. You can follow an unlimited number of people, but most people follow < 1000 others. With this style of query, the obvious optimization ...
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104 views

Database performs differently on the two same Xeon E3 1270-v3 Quad Core machines [closed]

Configuration: RAM: 16 GB DDR3. HDD: Seagate 500 GB 7200 3Gb/s 3.5 inch SATA - idential disks. Postgres 9.4, tried with 9.4.1 also Windows 2008 R2 Web Tried these tunings: work_mem = 32MB ...
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1answer
45 views

What is held in memory during the life of a CTE?

Assuming a multi-read/multi-write CTE, what exactly is held in memory during the life of the statement? Is all data except RETURNING data discarded at the end of each sub-statement?
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1answer
316 views

Can PostgreSQL use multiple partial indexes per query?

I have read that PostgreSQL can use multiple indexes in general, but in the specific case of a query that ranges across two indexes, will it use both? If so, will they be loaded sequentially or ...
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0answers
200 views

Slow transactions, many locks

At high load conditions the server app stops responding to client because begin/commit statements are executing very slowly (some take 15 seconds). The queries are simple - insert, update two columns ...
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2answers
163 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, ...
3
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1answer
263 views

Unused index in range of dates query

I have a query that is not using existing indices and I do not understand why. The table: mustang=# \d+ bss.amplifier_saturation Table ...
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0answers
116 views

PostgreSQL Performance - Many Large Databases

I run an internal (development) database server containing 25 databases each ~71GB in size. There are usually between 50 and 100 active connections at any given time. What can I do to help improve ...
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3answers
172 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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2answers
191 views

What indexes should one use to optimize a PostgreSQL query with a JOIN depth of 2?

Disclaimer: I am relatively new to PostgreSQL. I'm wondering how to optimize a query that does 2 INNER JOINs. My scenario is fairly simple: Select Posts with a photo (Posts.photo IS NOT NULL) and a ...
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155 views

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 ...
3
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1answer
115 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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1answer
314 views

Slow Postgres updates if OTHER columns are indexed?

Certain updates take far too long on large Postgres tables. Given these conditions: only one column is being updated, and it is non-indexed the column already has data in it for every row due to a ...