| Subject | Re: [firebird-support] Huge performance different from FB 2.5.2 vs FB 3.02 |
|---|---|
| Author | livius |
| Post date | 2017-09-25T17:25:45Z |
Hi,
look on this, only simple sample, by if join count increase you will see
difference faster.
Also faster if you join by few fields not only one.
At first look you see clearly where is filter and where is join
condition.
And then you can simply analyse if query use indexes on joined fields and
if it is true you go forward
and you analyze if filter “where” can be also indexed
SELECT
...
FROM
TABLE_A A
INNER JOIN TABLE_B B ON A.ID=B.ID
WHERE
A.FIELDX>5
and
SELECT
...
FROM
TABLE_A A, TABLE_B B
WHERE
A.ID=B.ID
AND A.FIELDX>5
regards,
Karol Bieniaszewski
Sent: Monday, September 25, 2017 7:02 PM
Subject: Re: [firebird-support] Huge performance different from FB
2.5.2 vs FB 3.02
Karol:
Not to highjack the thread, but a question. You stated:
style> this is terible to read. Please change join style to explicite join
>
A.ID=B.ID> instead SELECT .. FROM TABLE_A A, TABLE_B B WHERE
A.ID=B.ID> write SELECT .. FROM TABLE_A A INNER JOIN TABLE_B B ON
I'm not a DB expert, only as I have to but I read the first line easier
than the second line, but not without much difference. Why do you state it is
terrible?
Ed Dressel