Attention: To align with new corporate security policies, and to match policies adopted by other communities within Oracle, the My Oracle Support Community access requirements will change beginning September 18, 2025. MOSC will now require that member accounts in our community be associated to a *corporate* email address. This means that users with generic domains (such as gmail.com, yahoo.com, and others) will no longer be granted access to the discussion forums and ideas labs. If this policy affects you, act now to change the email address that is associated with your Oracle (and community) account. Alternatively, you can opt to create a new Oracle account that uses your corporate email domain.

Database Tuning (MOSC)

Why no single pass on a join between two tables with same PK

Dec 11, 2019 4:43PM edited Dec 24, 2019 5:46PM in Database Tuning (MOSC) 7 commentsAnswered ✓

Query plan execution conundrum:

Table A, 1M rows, PK on column A1.

Table B, 1T rows, PK on column B1.

Join A to B on A1=B1 to get matching rows in B.

PK index on A1 & B1.

Why wouldn't Oracle do this w/ONE pass on both tables using PK indexes? Work area size issue? Why would we need even 100M of PGA?

1

Howdy, Stranger!

To view full details, sign in to My Oracle Support Community.

Don't have a My Oracle Support Community account? Click here to get started.

Category Leaderboard

Top contributors this month