Celebrate National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

How to quickly enable constraint with ENABLE VALIDATE for a big table in 12c

Posted on 2016-10-24
13
Medium Priority
?
57 Views
Last Modified: 2016-10-27
Have a relatively big table T1 with 200 million rows. Its FK points to a table T2 with 10 millions. In 11gR2, it took 3 hours to enable the FK constraint, but in 12c, it takes days to do it. T1 and T2 in the 2 environments were created with the same setting.
Can any gurus shed some light on it? How to speed up the valid process in 12c? Thanks in advance.
0
Comment
Question by:jl66
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 6
  • 3
  • 2
  • +1
13 Comments
 
LVL 35

Assisted Solution

by:johnsone
johnsone earned 500 total points
ID: 41856999
The first thing I would look for is a missing index on T2.  Whatever the foreign key field(s) is that is referenced in T2 by T1 should have an index.
0
 
LVL 23

Assisted Solution

by:David
David earned 500 total points
ID: 41857058
Following that line of thought, are the indexes all valid? Are the table statistics current? And there's always the obvious question, what's different? Is something running against the 12C database that did not exist before?
0
 
LVL 38

Accepted Solution

by:
Geert Gruwez earned 1000 total points
ID: 41857130
enable it with novalidate first

from that point onwards, only valid entries will get in
1
Get your Disaster Recovery as a Service basics

Disaster Recovery as a Service is one go-to solution that revolutionizes DR planning. Implementing DRaaS could be an efficient process, easily accessible to non-DR experts. Learn about monitoring, testing, executing failovers and failbacks to ensure a "healthy" DR environment.

 

Author Comment

by:jl66
ID: 41857406
Thanks a lot for the info.
1) T1, T2 on the 2 environments are identical. The indexes are valid.
2) I tried to enable it with novalidate, but it is also very slow.

In 12c, there are no users who perform anything.

Which parts can I check to find the culprit?
0
 
LVL 35

Expert Comment

by:johnsone
ID: 41857428
Quite possible that you are waiting on a table lock then.
0
 

Author Comment

by:jl66
ID: 41857457
johnsone,
Yes. But no users used it then. How to fix this?
0
 

Author Comment

by:jl66
ID: 41857462
BTW, it took much longer time in 12c than 11gr2 if I do simple query: select count(1) from T1;
0
 

Author Comment

by:jl66
ID: 41857518
Further, I noticed the explain plans for the same query against the 2 databases are different.
12c:
...
2 |   INDEX FULL SCAN| IDX1

11gr2:
...
2 |   BITMAP CONVERSION COUNT     |                |   201M| 19049   (1)| 00:00:02 |
3 |   BITMAP INDEX FAST FULL SCAN| IDX2

Can any gurus share some knowledge on forcing to execute certain plan?

Both IDX1 and IDX2 are created in 11g and 12c databases.
0
 
LVL 35

Expert Comment

by:johnsone
ID: 41857572
To me it looks like an indexing issue.  To validate a constraint it shouldn't be doing a full scan on the index.
0
 
LVL 38

Expert Comment

by:Geert Gruwez
ID: 41858063
how much physical memory do you have
and how much do you allocate to the database ?

if you have allocated more than you have physical, it will be swapping
0
 

Author Comment

by:jl66
ID: 41859231
Total physical memory is 36GB, among which 6GB is for this database. There are the other databases on the same server. The total memory for databases is less than a half of 36GB.
0
 
LVL 23

Expert Comment

by:David
ID: 41859342
jj, did you ever happen to look into the optimizer statistics?
0
 

Author Closing Comment

by:jl66
ID: 41862539
Thanks. The kill shot is that the storage parameters are adjusted, which made huge difference.
0

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

How to Create User-Defined Aggregates in Oracle Before we begin creating these things, what are user-defined aggregates?  They are a feature introduced in Oracle 9i that allows a developer to create his or her own functions like "SUM", "AVG", and…
Using SQL Scripts we can save all the SQL queries as files that we use very frequently on our database later point of time. This is one of the feature present under SQL Workshop in Oracle Application Express.
This video shows, step by step, how to configure Oracle Heterogeneous Services via the Generic Gateway Agent in order to make a connection from an Oracle session and access a remote SQL Server database table.
This video shows how to copy a database user from one database to another user DBMS_METADATA.  It also shows how to copy a user's permissions and discusses password hash differences between Oracle 10g and 11g.

730 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question