Get a Lever and Pick Any Turtle:Lifting with MetadataCade Roux

cade@roux.org

Give me the place to stand, and I shall move the earth.

Start Simple

Scalethe

Technique

UseBasicConcepts

Expand to

Systems

Mixing Metaphors – We’re Going Down a Rabbit HolePam: And then outta that cake pops another stripper holding a smaller cake and then an even smaller stripper pops outta that one.

Michael: What is that smaller stripper holding?

Pam: A cupcake! It's cupcakes and strippers all the way down.

Avoid Injury

Metadata has always been thereCodd Rule #0: The RDBMS must use the relational facilities to manage the database

Metadata has always been there

Codd Rule #4: There must be an active online catalog based on the relational model

DBMeta

Demo

DBHealth

Tables

SPs

Views

SQL Server Basic Metadata Services INFORMATION_SCHEMA contains tables and

views (ANSI 92, kind of generic RDBMS model, doesn’t expose a lot of implementation details)

sys schema contains tables and views (more proprietary, particularly non-portable things like indexing features)

SQL Server Extended Properties You could make tables of additional information about

database objects DON’T Built-in extended properties work great for this! MS_Description: Microsoft’s standard “description” property sp_addextendedproperty, sp_updateextendedproperty,

sp_dropextendedproperty fn_listextendedproperty sys.extended_properties I’ll improve this in the DBMeta schema

DBMeta.PropertiesLayer this view on top of sys.extended_properties to:Make it easier to useGive a standard naming conventionEasier than CROSS APPLY

fn_listextendedproperty

DBMeta.AddXP, UpdateXP, DropXP Easier to use than sp_addextendedproperty,

sp_updateextendedproperty, sp_dropextendedproperty The builtin procs have some awkward hierarchy aspects: e.g.

a column or trigger is defined at level 2 where the table is level 1

DBMeta With some simple tools we now have an easier way of

dealing with the metadata in the extended properties This can be expanded at will to join regular base metadata

information, PIVOT with the property information and combine them in interesting ways

For instance, say your question was “I want to see NULLability (base metadata) of all money (base metadata) columns in tables in the Accounts subsystem (extended property) which have not been marked as reviewed. (extended property)” You can do that.

DBHealth Some questions about the health of the database system will

be very standard By health, I mean outside of integrity you can realistically

enforce with constraints and beyond what you might use DDL triggers for

Can we use the metadata to do something generally useful? Can we organize the health system using metadata so that it

is self-maintaining as much a possible?

Demo Data Let’s create some data structures in our Demo schema –

some tables and indexes

Let’s Make Up Some DBA Rules Arbitrary, but useful and chosen for variety Rule #1: All tables should be identified with a SUBSYSTEM

(Organizational Rule) Rule #2: No unique indexes with columns which allow NULLs

(Indexing Rule) Rule #3: No varchar(N) columns where N <= 2 (Table Design

Rule) Rule #0: We only want to enforce these on schemas under

management

Rule #0 We simply make a view DBHealth.MonitoredSchemas We’ll need to remember to use this view You could make a whole layer of views which filter through

this, of course

Rule #1Look for tables without extended property ‘SUBSYSTEM’

Rule #2Look for unique indexes where any of the columns in the index are NULLable.

Rule #3Find all varchar/nvarchar columns with length <= 2

What about exclusions?Let’s tag things for exclusion with extended properties!

Now we have a bunch of rules How do we organize them? Could we put them in individual views or procedures to make

them easy to use? Then make a master procedure which runs them all. But we’d need to make a list of all the procedures But what did we say? Let’s use the metadata to tag the procedures! We’ll mark the procedures We’ll categorize the procedures We’ll be able to look for all the marked procedures and run them

in an automated fashion – no new tables, limited maintenance!

Ideas For RulesAll procs in DBHealth should have

HEALTH_CHECK_PROC and HEALTH_CHECK_SET properties

Show me any unindexed tables (heap tables with no non-clustered indexes)

Show me any items tagged with a ‘TODO’ extended property

Show me all columns in the database which aren’t actually used (yes, you can do this!)

Let’s use this from a clientHealth Monitoring

.NETCode Generation

T-SQLT4

ContactEmail: cade@roux.orgTwitter: @caderouxWeb: http://www.caderoux.comSpeakerRate: http://speakerrate.com/caderoux