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From "Stephan van Loendersloot (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DERBY-6794) SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS(1) returns a long varchar (32,700)
Date Wed, 11 Feb 2015 15:39:12 GMT
Stephan van Loendersloot created DERBY-6794:
-----------------------------------------------

             Summary: SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS(1) returns a long varchar (32,700)
                 Key: DERBY-6794
                 URL: https://issues.apache.org/jira/browse/DERBY-6794
             Project: Derby
          Issue Type: Improvement
          Components: SQL
            Reporter: Stephan van Loendersloot
            Priority: Minor


The internal function SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS(1) returns a VARCHAR(32,700),
also known as a LONG VARCHAR in Derby.

In a lot of cases, this is not enough.

A couple of years ago at our company, we tried to mimic EXPLAIN functionality as sent by MySQL,
however, because MySQL didn't satisfy our needs, we needed a change, and needed somethings
similar, as reflected here http://mail-archives.apache.org/mod_mbox/db-derby-user/200810.mbox/%3C48F4483B.6040906@Sun.com%3E.

Now, we're building something like http://explain.depesz.com.

As an example, which consists of some ridiculously simple JSP; Not by any means complete,
but working processing engine for the explain plan, we created this: http://www.republika.nl/upload/explain_test.jpg

Soon, we'll provide a link to use this for all of you, like depesz.com does. We'll enter some
other JIRA issues to be sure about what we're doing, but basically it means you can simply
copy & paste your explain plans.

We do intend to give it back to the community, by releasing it via the Apache License v2.0,
but only when we're sure that every assumption we made is correct. In the meantime we'll provide
a URL where you can copy and paste explained plans, just like depesz.com does.

However, we've got some complicated queries, for which the runtime statistics retrieved by
the built-in function are bigger than a LONG VARCHAR...

Is there something we can do about that?

I've thought about changing code and making it a CLOB, but that would break backwards compatibility.

I'll give a full URL within 2 weeks, so you can try and test if you like what you see.

In the meantime... the issue is that we don't always get the full result plan, because of
character limitations...

Thanks for your attention.

-- Stephan van Loendersloot.



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