Linked Questions

3 votes
1 answer

Calculate storage size of rows? [duplicate]

In a multi-tenant only one DB, one column is used to isolate customers data, that is customer_id. Is it possible to get the storage size of a certain customer in all tables?
simo's user avatar
  • 271
8 votes
0 answers

How to do Statistics in Partial Indexes of PostgreSQL efficiently? [duplicate]

This answer motivated think again my following tables but I am still uncertain how to store variables/results from data analysis for quick selection in post-processing. If stored, I think it is well ...
Léo Léopold Hertz 준영's user avatar
0 votes
0 answers

Calculating the row size of a table [duplicate]

Is there a way to calculate the row size (in bytes) of a particular table in postgresql / pgadmin3?
Nick Ginanto's user avatar
86 votes
4 answers

Should I add an arbitrary length limit to VARCHAR columns?

According to PostgreSQL's docs, there's no performance difference between VARCHAR, VARCHAR(n) and TEXT. Should I add an arbitrary length limit to a name or address column? Edit: Not a dupe of: ...
Daniel Serodio's user avatar
123 votes
3 answers

Is a composite index also good for queries on the first field?

Let's say I have a table with fields A and B. I make regular queries on A+B, so I created a composite index on (A,B). Would queries on only A also be fully optimized by the composite index? ...
Luciano's user avatar
  • 1,661
52 votes
2 answers

Best way to populate a new column in a large table?

We have a 2.2 GB table in Postgres with 7,801,611 rows in it. We are adding a uuid/guid column to it and I am wondering what the best way to populate that column is (as we want to add a NOT NULL ...
Collin Peters's user avatar
49 votes
2 answers

Configuring PostgreSQL for read performance

Our system writes a lots of data (kind of Big Data system). Write performance is good enough for our needs but read performance is really too slow. The primary key (constraint) structure is similar ...
JPelletier's user avatar
28 votes
5 answers

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 ...
Fabrizio Mazzoni's user avatar
53 votes
1 answer

Indexes: integer vs string performance if the number of nodes is the same

I am developing an application in Ruby on Rails with the PostgreSQL (9.4) database. For my use case, columns in tables will be looked up very frequently, as the whole point of the application is ...
Chris Cirefice's user avatar
36 votes
1 answer

VACUUM returning disk space to operating system

VACUUM usually does not return disk space to operating system, except in some special cases. From the docs: The standard form of VACUUM removes dead row versions in tables and indexes and marks the ...
Vadim Samokhin's user avatar
43 votes
1 answer

Would index lookup be noticeably faster with char vs varchar when all values are 36 chars

I have a legacy schema (disclaimer!) that uses a hash-based generated id for the primary key for all tables (there are many). An example of such an id is: 922475bb-ad93-43ee-9487-d2671b886479 There ...
Bohemian's user avatar
  • 673
23 votes
2 answers

PostgreSQL "size of temporary files"

I've imported data into a new database (about 600m rows of timestamp, integer, double). I then created some indexes and tried to alter some columns (got some out of space issues), the database is ...
Ofiris's user avatar
  • 811
25 votes
1 answer

What is the overhead for varchar(n)?

I wanted to ask for the meaning of this fragment from Postgres doc regarding varchar(n) type: The storage requirement for a short string (up to 126 bytes) is 1 byte plus the actual string, which ...
keypress's user avatar
  • 353
19 votes
1 answer

Postgres: check disk space taken by materialized view?

I know how to check the size of indexes and tables in Postgres (I'm using version 9.4): SELECT relname AS objectname, relkind AS objecttype, reltuples AS "#entries", pg_size_pretty(relpages::...
Richard's user avatar
  • 333
14 votes
1 answer

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 ...
ebi's user avatar
  • 243

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