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HOLISTIC OPTIMIZATION OF DATABASE APPLICATIONS Karthik Ramachandra , IIT Bombay Joint work with R Guravannavar (IIT Hyderabad ), M Chavan & S Sudarshan (IIT Bombay). LoopContextTable lct = new LoopContextTable(); while ( ! category != null){ LoopContext ctx = lct.createContext();

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HOLISTIC OPTIMIZATION OF DATABASE APPLICATIONS

KarthikRamachandra, IIT Bombay

Joint work with R Guravannavar(IIT Hyderabad), M Chavan & S Sudarshan (IIT Bombay)

LoopContextTable lct = new LoopContextTable();

while(!category != null){

LoopContext ctx = lct.createContext();

stmt.setInt(1, category);

ctx.setInt(”category”, category);

category = getParent(category);

stmt.addBatch(ctx);

}

stmt.executeBatch();

for (LoopContext ctx : lct) {

category = ctx.getInt(”category”);

ResultSet rs = stmt.getResultSet(ctx);

rs.next();

int count = rs.getInt(”count");

sum += count;

print(category+ ”: ” +count);

}

S1

S2

S3

while(category!= null){

inttemp = category;

category = getParent(category);

qt.bind(1, temp);

intcount = executeQuery(qt);

sum = sum + count;

}

S1:

S5:

S4

S4:

  • Applications often invoke Database queries/Web Service requests
      • repeatedly (with different parameters)
      • synchronously (blocking on every request)
  • Naive iterative execution of such queries: inefficient
      • No sharing of work (eg. Disk IO)
      • Network round-trip delays

The Problem

S2:

  • Analyze application programs along with embedded queries
  • Transform programs using equivalence rules and semantics preserving reordering
  • Rewrite queries using decorrelation, APPLY operator, etc.
  • DBridge: Implements these ideas on Java/JDBC code, using Soot framework
  • Program rewrite using DBridge API identical for both solutions
  • Repeated invocation of a query automatically replaced by a single invocation of its batched form
  • Enables use of efficient set-oriented query execution plans
  • Repeated synchronous invocation of a queries automatically replaced by asynchronous submission
  • Application can perform other work while query executes
  • Multiple queries could be issued concurrently

S3:

Performance gains (upto 7x)!

Soln 1: Batching

Soln 2: Asynchronous Submission

Approach

Parsing

Data flow analysis

Decompile

  • not within the database engine

The Problem is

  • in the way queries are invoked from the application

S1:

while(category!= null){

qt.bind(1, category);

intcount = executeQuery(qt);

sum = sum + count;

category = getParent(category);

}

S2:

Query optimization: time to think out of the box!

S3:

S4:

Program Transformation

  • Handles complex programs with
  • Conditional branching
  • Nested Loops

Threads

Parameter Batch

(temp table)

Reordered program before Loop Splitting

Data

Dependence

Graph(DDG)

Input program

DB

Set of ResultSets

Output program after Loop Splitting

Submit Q

Query

rewrite

Experiment 1: DB Query invocation

Only Asynchronous Submission applies

DB

Result array

Batching not possible here as there is no set-oriented interface exposed by the web service

Batching mode

Asynchronous mode

Identical API interface for Batching and Asynchronous approach

Experiment 2: Web Service invocation