Hello,
On Firebird 2.5.3 (SS) 64 Bit
CREATE GENERATOR GEN_test_ID;
CREATE TABLE test (
id INTEGER NOT NULL,
reference INTEGER,
key INTEGER,
value VARCHAR(200)
);
ALTER TABLE test ADD CONSTRAINT PK_test PRIMARY KEY (Id);
SET TERM ^ ;
CREATE OR ALTER TRIGGER test_BIU0 FOR test
ACTIVE BEFORE INSERT OR UPDATE POSITION 0
AS
BEGIN
IF (NEW.Id IS NULL) THEN
NEW.Id = GEN_ID(GEN_test_ID,1);
END
^
SET TERM ; ^
Insert 999 random records
dublicate one record (with new id of course
select min(t.Id) FROM test t
group by t.reference, t.key
having count(*) > 1
costs 1000 Non indexed reads
select * from test where Id in (
select min(t.Id) FROM test t
group by t.reference, t.key
having count(*) > 1
)
costs 1001000 non indexed reads
Why?
Creating an index modifies only non indexed in indexed reads.
Björn
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