Postgres and multiple updates in one statement - Mailing list pgsql-general

From Jamie Lawrence-Jenner
Subject Postgres and multiple updates in one statement
Date
Msg-id !&!AAAAAAAAAAAYAAAAAAAAACSjyZCDEbJLs7GIuOJ8tGbCgAAAEAAAAN23KwkdXSpGjZZEv3dLuNgBAAAAAA==@autovhc.co.uk
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Re: Postgres and multiple updates in one statement
List pgsql-general

Hi there

 

We have a function which runs a set of update clauses and we are considering putting all the update clauses into one statement.

 

I would like to understand how postgres handles multiple updates. If we were to send 5 update statements in one sql statement to the db would it:

 

Do 5 passes on the table, on each pass, retrieve the id then update the row

 

Do 1 pass to retrieve the 5 primary keys, then update all rows in parallel

 

Apart from saving on the overhead of having to open up 5 separate connections, what are the benefits to passing in multiple updates in one statement?

 

Many thanks,

 

Jamie

 

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