When to use insert on Conflict Statement in PostgreSQL?

When to use insert on Conflict Statement in PostgreSQL?

The idea is that when you insert a new row into the table, PostgreSQL will update the row if it already exists, otherwise, PostgreSQL inserts the new row. That is why we call the action is upsert (update or insert). To use the upsert feature in PostgreSQL, you use the INSERT ON CONFLICT statement as follows:

How to perform the PostgreSQL upsert in an existing table?

You can upsert as many columns as you want using the same command syntax: In our next example, we are upserting the columns firstname and lastname to the table students: The result will look like the following: When you’re performing an INSERT operation in PostgreSQL, there may be times when a duplicate record already exists in the table.

Can you use upsert in PL / pgSQL?

It’s also possible to use PL/pgSQL to create a custom upsert function. And now, we can do an explicit upsert using the on conflict clause of the insert statement. Before we go any further, let’s give ourselves an example database for illustrative purposes.

How does upsert work in a relational database?

In relational databases, the term upsert is referred to as a merge. The idea is that when you insert a new row into the table, PostgreSQL will update the row if it already exists, otherwise, PostgreSQL inserts the new row.

How to append an item to an array in PostgreSQL?

To append an item to array in PostgreSQL you can use || operator or array_append function.

When to use upsert or update in PostgreSQL?

The idea is that when you insert a new row into the table, PostgreSQL will update the row if it already exists, otherwise, PostgreSQL inserts the new row. That is why we call the action is upsert (update or insert).

When does PostgreSQL guarantee an atomic insert or update?

If an attempt at inference is unsuccessful, an error is raised. ON CONFLICT DO UPDATE guarantees an atomic INSERT or UPDATE outcome; provided there is no independent error, one of those two outcomes is guaranteed, even under high concurrency. This is also known as UPSERT — “UPDATE or INSERT”.

Is there a naming conflict between function parameter and result of?

ERROR: column reference “ts” is ambiguous LINE 1: SELECT ts, f.foo, b.bar ^ DETAIL: It could refer to either a PL/pgSQL variable or a table column. I know I can use different names or a subquery or use another function.

Can you generate a statement with only one conflict target?

You can typically (I would think) generate a statement with only one on conflict that specifies the one and only constraint that is of relevance, for the thing you are inserting. Because typically, only one constraint is the “relevant” one, at a time. (If many, then I’m wondering if something is weird / oddly-designed, hmm.)

Is there an equivalent to insert in PostgreSQL?

Postgres hasn’t implemented an equivalent to INSERT OR REPLACE. From the ON CONFLICT docs (emphasis mine): It can be either DO NOTHING, or a DO UPDATE clause specifying the exact details of the UPDATE action to be performed in case of a conflict. Though it doesn’t give you shorthand for replacement, ON CONFLICT DO UPDATE applies more generally,

Is it possible to add more conflict targets in on conflict?

In nowadays is (seems) impossible. Neither the last version of the ON CONFLICT syntax permits to repeat the clause, nor with CTE is possible: not is possible to breack the INSERT from ON CONFLICT to add more conflict-targets. Create a constraint (foreign index, for example).