Download Data Mining Query Languages

Data Mining Query
Languages
Kristen LeFevre
April 19, 2004
With Thanks to Zheng Huang and Lei Chen
Outline
Introduce the problem of querying
data mining models
 Overview of three different solutions
and their contributions
 Topic for Discussion: What would an
ideal solution support?

Problem Description

You guys are armed with two powerful tools



Database management systems
Efficient and effective data mining algorithms
and frameworks
Generally, this work asks:


“How can we merge the two?”
“How can we integrate data mining more
closely with traditional database systems,
particularly querying?”
Three Different Answers
DMQL: A Data Mining Query
Language for Relational Databases
(Han et al, Simon Fraser University)
 Integrating Data Mining with SQL
Databases: OLE DB for Data Mining
(Netz et al, Microsoft)
 MSQL: A Query Language for
Database Mining (Imielinski &
Virmani, Rutgers University)

Some Common Ground




Create and manipulate data mining models
through a SQL-based interface (“Commanddriven” data mining)
Abstract away the data mining particulars
Data mining should be performed on data in
the database (should not need to export to
a special-purpose environment)
Approaches differ on what kinds of models
should be created, and what operations we
should be able to perform
DMQL

Commands specify the following:


The set of data relevant to the data mining
task (the training set)
The kinds of knowledge to be discovered
•
•
•
•
•
Generalized relation
Characteristic rules
Discriminant rules
Classification rules
Association rules
DMQL

Commands Specify the following:

Background knowledge
• Concept hierarchies based on attribute
relationships, etc.

Various thresholds
• Minimum support, confidence, etc.
DMQL

Specify background
knowledge
Specify rules to be
discovered
Relevant attributes or
aggregations
Collect the set of
relevant data to mine
Specify threshold
parameters
Syntax
use database <database_name>
{use hierarchy <hierarchy_name> for
<attribute>}
<rule_spec>
related to <attr_or_agg_list>
from <relation(s)>
[where <conditions>]
[order by <order list>]
{with [<kinds of>] threshold =
<threshold_value> [for <attribute(s)>]}
DMQL
Syntax <rule_spec>
find classification rules [as <rule_name>]
[according to <attributes>]

Find association rules [as <rule_name>]
generalize data [into <relation_name>]
others
DMQL
use database Hospital
find association rules as Heart_Health
related to Salary, Age, Smoker,
Heart_Disease
from Patient_Financial f, Patient_Medical m
where f.ID = m.ID and m.age >= 18
with support threshold = .05
with confidence threshold = .7
DMQL
DMQL provides a display in
command to view resulting rules, but
no advanced way to query them
 Suggests that a GUI interface might
aid in the presentation of these results
in different forms (charts, graphs, etc.)

MSQL
Focus on Association Rules
 Seeks to provide a language both to
selectively generate rules, and
separately to query the rule base
 Expressive rule generation language,
and techniques for optimizing some
commands

MSQL

Get-Rules and Select-Rules Queries
Get-Rules operator generates rules over
elements of argument class C, which satisfy
conditions described in the “where” clause
[Project Body, Consequent,
confidence, support]
GetRules(C) [as R1]
[into <rulebase_name>]
[where <conds>]
[sql-group-by clause]
[using-clause]

MSQL

<conds> may contain a number of
conditions, including:

restrictions on the attributes in the body or
consequent
• “rule.body HAS {(Job = ‘Doctor’}”
• “rule1.consequent IN rule2.body”
• “rule.consequent IS {Age = *}”
in, has, and is are rule
subset, superset,
and equality
respectively


pruning conditions (restrict by support,
confidence, or size)
Stratified or correlated subqueries
MSQL
GetRules(Patients)
where Body has {Age = *}
and Support > .05 and Confidence > .7
and not exists ( GetRules(Patients)
Support > .05 and
Confidence > .7
and R2.Body HAS R1.Body)
Retrieve all rules with descriptors of the form “Age = x” in the body,
except when there is a rule with equal or greater support and
confidence with a rule containing a superset of the descriptors in
the body
MSQL
correlated
stratified
GetRules(C) R1
where <pruning-conds>
and not exists ( GetRules(C) R2
where <same pruning-conds>
and R2.Body HAS R1.Body)
GetRules(C) R1
where <pruning-conds>
and consequent is {(X=*)}
and consequent in (SelectRules(R2)
where consequent is {(X=*)}
MSQL

Nested Get-Rules Queries and their
optimization


Stratified (non-corrolated) queries are
evaluated “bottom-up.” The subquery is
evaluated first, and replaced with its results
in the outer query.
Correlated queries are evaluated either topdown or bottom-up (like “loop-unfolding”),
and there are rules for choosing between the
two options
MSQL
GetRules(Patients)
where Body has {Age = *}
and Support > .05 and Confidence > .7
and not exists ( GetRules(Patients)
Support > .05 and
Confidence > .7
and R2.Body HAS R1.Body)
MSQL
Top-Down Evaluation
GetRules(Patients)
where Body has {Age = *}
and Support > .05 and Confidence > .7
For each rule produced by the outer, evaluate the
inner
not exists ( GetRules(Patients)
Support > .05 and
Confidence > .7
and R2.Body HAS R1.Body)
MSQL
Bottom-Up Evaluation
not exists ( GetRules(Patients)
Support > .05 and
Confidence > .7
and R2.Body HAS R1.Body)
For each rule produced by the inner, evaluate the
outer
GetRules(Patients)
where Body has {Age = *}
and Support > .05 and Confidence > .7
MSQL

Choosing between the two
 In general, evaluate the expression with more
restrictive conditions first
 Heuristic rules
Meant to prevent
unconstrained
queries from being
evaluated first
• Evaluate the query with higher support threshold first
• Next consider confidence threshold
• A (length = x) expression is in general more restrictive
than (length > x), which is more restrictive than (length
< x)
• “Body IS (constant expression)” is more restrictive than
“Body HAS”, which is more restrictive than “Body IN”
• Next consider “Consequent IN” expressions
• Descriptors of for (A = a) are more restrictive than
wildcards such as (A = *)
OLE DB for DM


An extension to the OLE DB interface for
Microsoft SQL Server
Seeks to support the following ideas:


None of the
others
seemed to
support this


Define a model by specifying the set of
attributes to be predicted, the attributes used
for the prediction, and the algorithm
Populate the model using the training data
Predict attributes for new data using the
populated model
Browse the mining model (not fully
addressed because it varies a lot by model
type)
OLE DB for DM

Defining a Mining Model


Identify the set of data attributes to be
predicted, the set of attributes to be used for
prediction, and the algorithm to be used for
building the model
Populating the Model


Pull the information into a single rowset
using views, and train the model using the
data and algorithm specified
Supports complex objects, so rowset may be
hierarchical (see paper for more complex
examples)
OLE DB for DM

Using the mining model to predict

Defines a new operator prediction join.
A model may be used to make
predictions on datasets by taking the
prediction join of the mining model
and the data set.
OLE DB for DM
CREATE MINING MODEL [Heart_Health Prediction]
[ID] Int Key,
[Age] Int,
[Smoker] Int,
[Salary] Double discretized,
[HeartAttack] Int PREDICT, %Prediction column
USING [Decision_Trees_101]
Identifies the source columns for the training
data, the column to be predicted, and the data
mining algorithm.
OLE DB for DM
INSERT INTO [Heart_Health Prediction]
([ID], [Age], [Smoker], [Salary])
SELECT [ID], [Age], [Smoker], [Salary] FROM
Patient_Medical M, Patient_Financial F
WHERE M.ID = F.ID
The INSERT represents using a tuple for
training the model (not actually inserting it into
the rowset).
OLE DB for DM
SELECT t.[ID],
[Heart_Health Prediction].[HeartAttack]
FROM [Heart_Health Prediction]
PREDICTION JOIN (
SELECT [ID], [Age], [Smoker], [Salary]
FROM Patient_Medical M, Patient_Financial F
WHERE M.ID = F.ID) as t
ON [Heart_Health Prediction].Age = t.Age AND
[Heath_Health Prediction].Smoker = t.Smoker
AND [Heart_Health Prediction].Salary =
t.Salary
Prediction join connects the model and an actual data
table to make predictions
Key Ideas
Important to have an API for creating
and manipulating data mining models
 The data is already in the DBMS, so it
makes sense to do the data mining
where the data is
 Applications already use SQL, so a
SQL extension seems logical

Key Ideas



Need a method for defining data mining
models, including algorithm specification,
specification of various parameters, and
training set specification (DMQL, MSQL,
ODBDM)
Need a method of querying the models
(MSQL)
Need a way of using the data mining model
to interact with other data in the database,
for purposes such as prediction (ODBDM)
Discussion Topic:
What Functionality would
and Ideal Solution
Support?