Re: Implementing Incremental View Maintenance

However, multiple tables can be modified *before* AFTER STATEMENT triggers are fired.

CREATE TABLE example1 (a int);

CREATE TABLE example2 (a int);

CREATE INCREMENTAL MATERIALIZED VIEW mv AS

SELECT example1.a, example2.a

FROM example1 JOIN example2 ON a;

WITH

  insert1 AS (INSERT INTO example1 VALUES (1)),

  insert2 AS (INSERT INTO example2 VALUES (1))

SELECT NULL;

Changes to example1 are visible in an AFTER STATEMENT trigger on example2, and vice versa. Would this not result in the (1, 1) tuple being "double-counted"?

IVM needs to either:

(1) Evaluate deltas "serially' (e.g. EACH ROW triggers)

(2) Have simultaneous access to multiple deltas:

delta_mv = example1 x delta_example2 + example2 x delta_example1 - delta_example1 x delta_example2

This latter method is the "logged" approach that has been discussed for deferred evaluation.

tl;dr It seems that AFTER STATEMENT triggers required a deferred-like implementation anyway.