Question

I want to perform an SQL query that is logically equivalent to the following:

DELETE FROM pond_pairs
WHERE
  ((pond1 = 12) AND (pond2 = 233)) OR
  ((pond1 = 12) AND (pond2 = 234)) OR
  ((pond1 = 12) AND (pond2 = 8)) OR
  ((pond1 = 13) AND (pond2 = 6547)) OR
  ((pond1 = 13879) AND (pond2 = 6))

I will have hundreds of thousands pond1–pond2 pairs. I have an index on (pond1, pond2).

My limited SQL knowledge came up with several approaches:

1. Run the whole query as is.
2. Batch the query up into smaller queries with n WHERE conditions
3. Save the pond1–pond2 pairs into a new table, and do a subquery in the WHERE clause to identify
4. Convert the python logic which identifies rows to delete into a stored procedure. Note that I am unfamiliar with programming stored procedures and thus this would probably involve a steep learning curve.

I am using postgres if that is relevant.

Answer 1

For a large number of pond1-pond2 pairs to be deleted in a single DELETE, I would create temporary table and join on this table.

-- Create the temp table:
CREATE TEMP TABLE foo AS SELECT * FROM (VALUES(1,2), (1,3)) AS sub (pond1, pond2);

-- Delete
DELETE FROM bar 
USING  
  foo -- the joined table
WHERE 
  bar.pond1= foo.pond1 
AND 
  bar.pond2 = foo.pond2;