All posts by Mark Jacobsen

DB2

Should I use DB2 LOAD or IMPORT?

12/02/2013 Mark Jacobsen Leave a comment

Use LOAD when:

Performance is critical. Load outperforms Import in all scenarios, sometimes by as much as a factor of 10 (May be closer to 6 times for UNIX systems).
You want to LOAD FROM CURSOR to avoid the creation of an intermediate file.

Use IMPORT when:

You have smaller tables.
You want additional “safety” in the case of an error.
Target table needs to be created from the input file (applicable to PC/IXF files only.)
Logging of every inserted record is necessary.
You require triggers to fire.
You need to be able to update the table while appending data to the table.

In general I would recommend IMPORT unless performance is absolutely critical or you have more than 10 million records (yes, that’s relatively arbitrary – the point is a LOT of data). The primary reason for this is that a botched load can send your entire table space into backup pending and leave you dead in the water. If you do decided to do a load, make sure you include steps to recover from the failed load (but that’s a topic for another day).

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Disclaimer: Thoughts and opinions are my own, and do not reflect the views of any employer, family member, friend, or anyone else. Some links may be affiliate links, but I don't link to anything I don't use myself.

Java

How do I override the JVM Heap Size?

12/02/2013 Mark Jacobsen Leave a comment

If you’ve ever received a java.lang.OutOfMemoryError when processing a large amount of data, there’s a chance you need to manually specify the JVM size if you can. Here’s an example…

java -Xms64m -Xmx256m MyProgram

… Of course, another option you may want to consider is to structure your program more efficiently (i.e. don’t store all that data in memory, process in blocks, use a tool more suitable to the task like BCP or DB2 LOAD).

Want to read more on the subject? Read this

Weekly Round-Up

Weekly Round-Up: 11/24/13 to 11/30/13

12/01/2013 Mark Jacobsen Leave a comment

The Weekly Round-Up is a once weekly collection of my #1Aday daily shares. Hope you find something of interest!

Wed 11/27
More good reasons to skip Black Friday: The Dirty Secret of ‘Discounts’—Black Friday and Beyond – WSJ.com – http://mjg2.net/l/1882

DB2

DB2 Duplicate Key Debugging

11/26/2013 Mark Jacobsen Leave a comment

If you’ve ever gotten a DB2 error like this…

SQL0803N  One or more values in the INSERT statement, UPDATE statement, 
or foreign key update caused by a DELETE statement are not valid because 
the primary key, unique constraint or unique index identified by "1" 
constrains table "XX.TABLE_NAME" from having duplicate values for 
the index key.  SQLSTATE=23505

You may be asking yourself, but exactly which unique index is causing the problem?

Use the info from the error along with this query to find out:

SELECT *
FROM   SYSCAT.INDEXES
WHERE  IID = 1
       AND TABSCHEMA = 'XX'
       AND TABNAME = 'TABLE_NAME';

Of course you will want to replace the WHERE clause conditions with your values.

Weekly Round-Up

Weekly Round-Up: 11/17/13 to 11/23/13

11/24/2013 Mark Jacobsen Leave a comment

The Weekly Round-Up is a once weekly collection of my #1Aday daily shares. Hope you find something of interest!

Mon 11/18
12 Powerful Habits Of Happy Relationships – http://mjg2.net/l/1881

Weekly Round-Up

Weekly Round-Up: 11/10/13 to 11/16/13

11/17/2013 Mark Jacobsen Leave a comment

The Weekly Round-Up is a once weekly collection of my #1Aday daily shares. Hope you find something of interest!

Tue 11/12
Consumerism In America: How Your Stuff Is Killing You And You Don’t Even Know It – http://markjacobsen.net/l/1877

Wed 11/13
10 Things Every Couple Needs To Stop Doing – http://markjacobsen.net/l/1878

Thu 11/14
Working Long Hours Is Like Working for Free – http://markjacobsen.net/l/1879

Fri 11/15
Marriage Isn’t For You – Great article by @SethAdamSmith – http://markjacobsen.net/l/1880

Announcements

Mind lending a hand?

11/12/2013 Mark Jacobsen Leave a comment

Thanks ahead of time to everyone who’s already taken a moment to help out, but if you haven’t had the chance yet I’d appreciate your assistance in giving me just a few clicks. Since one of the most important signals to search engines for “recommending” sites when you do a search is social media presence, I was hoping you might be willing to lend a hand by giving my company, Communication Freedom, a link little juice.

Just visit the various sites below and like, follow, or circle it from your account. Don’t worry, I won’t start sending you a bunch of spam 🙂

Facebook

Twitter

Google+ (be sure to “Follow” and “+1”)

Perl

How to tell if a Perl Module is Installed

11/04/2013 Mark Jacobsen Leave a comment

Want to check if a perl module is installed on your system? There’s a oneliner for that! Here’s an example…

perl -e "use Text::CSV"

… which would of course check if Text::CSV could be loaded. If it can, nothing will be printed. If not, you’ll get an error with some possibly useful information to figuring out why not.

DB2

Generate a GUID or UUID in DB2

10/30/2013 Mark Jacobsen Leave a comment

Want to generate the equivalent of a GUID or UUID in DB2? The closest you’ll get is with GENERATE_UNIQUE(), but beware that you need to do some conversion on it as the value is “BIT DATA” and not character data. To put the value into a typical CHAR or VARCHAR field (like you would with a java UUID), use this…

select TRIM(CHAR(HEX(GENERATE_UNIQUE()))) from sysibm.sysdummy1;

I should probably also mention that there is the IDENTITY and SEQUENCE, but the GENERATE_UNIQUE() function is the closest you’ll get to a GUID or UUID.

Weekly Round-Up

Weekly Round-Up: 10/13/13 to 10/19/13

10/20/2013 Mark Jacobsen Leave a comment

The Weekly Round-Up is a once weekly collection of my #1Aday daily shares. Hope you find something of interest!

Mon 10/14
Peter Shankman @PeterShankman says: Stop Tying Your Employee’s Hands – http://markjacobsen.net/l/1875