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127 votes
5 answers
327k views

Best practice between using LEFT JOIN or NOT EXISTS

Is there a best practice between using a LEFT JOIN or a NOT EXISTS format? What is benefit to using one over the other? If none, which should be preferred? SELECT * FROM tableA A LEFT JOIN tableB B ...
Michael Richardson's user avatar
40 votes
2 answers
6k views

IF EXISTS taking longer than embedded select statement

When I run the following code it takes 22.5 minutes and does 106million reads. However, if I run just the inner select statement by itself it only takes 15 seconds and does 264k reads. As a side note, ...
Chris Woods's user avatar
  • 1,771
11 votes
1 answer
5k views

Does the SQL Spec require a GROUP BY in EXISTS ()

Microsoft currently permits this syntax. SELECT * FROM ( VALUES (1) ) AS g(x) WHERE EXISTS ( SELECT * FROM ( VALUES (1),(1) ) AS t(x) WHERE g.x = t.x HAVING count(*) > 1 ); Notice ...
Evan Carroll's user avatar
  • 63.9k
11 votes
1 answer
32k views

pg_restore ERROR: "Relation does not exist" and creating new database

I have made a backup of my specific tables that I want to restore into a new database using: call pg_dump -Fc -h server -d database -U user -p password -v -f dump.sql -t public.table1 -t public....
Ian23's user avatar
  • 113
3 votes
1 answer
2k views

Full text search on two tsvector columns

I'm trying to do a full text search across two columns of two separate tables in PostgreSQL 9.4.2. The tables and columns are: article.article_title keyword.keyword Where there is a many-to-many ...
sammy88888888's user avatar
0 votes
1 answer
5k views

How can I create a bool column for a view based on the result of a statement?

I'm using PostgreSQL as my database. CREATE TABLE groups ( id SERIAL NOT NULL, name TEXT NOT NULL, PRIMARY KEY (id), UNIQUE (name) ); CREATE TABLE users ( id ...
Bryan's user avatar
  • 417