Linked Questions

0
votes
1answer
3k views

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?
8
votes
0answers
136 views

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 ...
0
votes
0answers
57 views

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?
83
votes
3answers
29k views

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? ...
22
votes
5answers
77k views

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 ...
38
votes
2answers
32k views

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 ...
32
votes
2answers
29k views

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 ...
30
votes
1answer
7k views

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 ...
25
votes
1answer
17k views

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 ...
16
votes
1answer
23k views

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 ...
12
votes
2answers
25k views

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 ...
13
votes
1answer
5k views

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::...
14
votes
1answer
4k views

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 ...
10
votes
2answers
2k views

What fillfactor for caching table?

I have heavily updated / accessed table where I store serialized java objects. They are in the table for 2-3 hours (also are being updated during that period) and then removed. Size of table is around ...
8
votes
3answers
2k 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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