Arquiteturas Avançadas de SGBDs

• Por que processamento em paralelo?• Consultas 'paralelizáveis'• Formas de processamento em paralelo• Critérios de escolha de processamento em

paralelo• Solução Oracle p/ processamento em

paralelo• Conclusões

Por que processamento em paralelo?

• Contar os registros de um imenso arquivoSQL> SELECT degree, instances FROM user_tables WHERE table_name = 'Faturamento'; DEGREE INSTANCES 1 1

SQL> SET TIMING ONSQL> SELECT COUNT(*) FROM Faturamento;

COUNT(*) 12384004 Elapsed: 00:58:49.01

Por que processamento em paralelo?

• Contar os registros de um imenso arquivoSQL> ALTER TABLE Faturamento PARALLEL (DEGREE 8); Table altered.SQL> SELECT degree, instances FROM user_tables WHERE table_name = 'Faturamento'; DEGREE INSTANCES 8 1

SQL> SET TIMING ONSQL> SELECT COUNT(*) FROM Faturamento;

COUNT(*) 12384004 Elapsed: 00:08:13.23

CLIENT

QC

PQ1 PQ2 PQ3

QC - Query CoordinatorPQ - Parallel Query Slave

0 5 10 15 20

0 2

SEQUENCIAL

PARALELO

segundos

0.2 segundos

0 15minutos

0 2

SEQUENCIAL

PARALELO

horas

10 segs

10 segs

Requisitos de Consultas com Paralelização

• Resultados simples– Facilidade de integrar subresultados

• Subconsultas não-correlacionadas– Uma subconsulta não passa/recebe parâmetro

de outra (subconsultas independentes)• Subconsultas não-concorrentes

– Uma subconsulta não disputa recursos com outra

Formas de Processamento em Paralelo

• Consulta– "Table full scan"

• "Dynamic partitioning"– "Indexed range scan"

• "Static Partitioned table"• "Static Partitioned index"

– Consultas distribuídas• SGBD

– “Parallel query”– “Parallel server”– “Distributed DB”

Formas de Processamento em Paralelo

• Hardware Paralelo– "Uniprocessor system“, com “threads”– "Symetric multiprocessing (SMP) system"– "Massively parallel processing (MPP) system"

Hardware Paralelo

CPU

SYSTEM BUS

MEMORYI/O

CONTROLLERI/O

CONTROLLER

DISK DISK

Uniprocessor System

CPU

SYSTEM BUS

MEMORYI/O

CONTROLLERI/O

CONTROLLER

DISK DISK

CPU

SMP System

CPU

SYSTEM BUS

MEMORYI/O

CONTROLLERI/O

CONTROLLER

DISK DISK

NÓ

NÓ-1

NÓ-3 NÓ-4

NÓ-2

SYST

EM IN

TER

CO

NN

E CT

MPP

Sy s

tem

Hardware para consultas distribuídas

1.2 Terabytes ofDisk Storage16 Node MPP

Cost: $10M

1.2 Terabytes ofDisk Storage

4 Node MPPCost: $3M

300 GB ofDisk Storage

300 GB ofDisk Storage

300 GB ofDisk Storage

300 GB ofDisk Storage

4 SMP ServersCost: 4x$1M = $4M

TotalHardwareCost: $7M

MáquinaMPP

MáquinaSMP

MáquinaSMP Máquina

SMP

MáquinaSMP

Internet(Extranet)(Intranet)

Critérios de Escolha de Hardware para Processamento em Paralelo

Hardware “ParallelQuery”

“ParallelServer”

“Uniprocessor” Talvez Não

SMP Sim (a melhor opção)

Não

MPP Sim Sim

Critérios de Escolha de Hardware para Processamento em Paralelo

Hard-ware

Confia-bilidade

Disponi-bilidade

Gerên-cia

Desem-penho

Escala

“Uniprocessor”

Excelente Pobre Excelente Pobre Pobre

SMP Bom Bom Bom Excelente Bom

MPP Pobre Bom Pobre Bom Excelente

Solução Oracle p/ Consulta em Paralelo

Opção “Parallel Query”

Consulta em Paralelo: Full Table Scan

• Arquitetura SMP• Tabelas espalhadas em vários discos

Create tablespace exemploDatafile `datafile_on_disk1´ size 536879004,Datafile `datafile_on_disk2´ size 536879004,Datafile `datafile_on_disk3´ size 536879004,Datafile `datafile_on_disk4´ size 536879004 ...

• Grau de paralelismo > no. de CPUs– No. de “threads” por CPU

9/133/13

1/13

CLIENT

QC

PQ1 PQ2 PQ3

Full Table ScanDynamic Partitioning Bloco cheio

Bloco vazio

9/133/13

1/13

CLIENT

QC

PQ1 PQ2 PQ3

Full Table ScanDynamic Partitioning

ORACLESERVER

PROCESS(QC)

PARALLELQUERY SLAVE

PROCESS(PQ)

REQUESTS

DATA REQUESTS

DATAFull Table Scan: Dynamic Partitioning

QUERY

INSERT

TABLE 2

TABLE 1

QC

CREATE

Full Table Scan: Dynamic Partitioning

SET TIMING ONDELETEFROM faturamentoWHERE data_fat < ´01-JAN-96´;

1803773 rows deleted.Elapsed: 22:44:55.03

SET TIMING ONCREATE TABLE n_faturamentoPARALLEL (DEGREE 8)TABLESPACE fatSTORAGE (INITIAL 4M NEXT

4M PCTINCREASE 0)AS

SELECT *FROM faturamentoWHERE data_fat ≥ ´01-JAN-96´;

Elapsed: 00.50.03.43

RENAME faturamento TO ant_faturamento;

Elapsed: 00:00:01.01

RENAME n_faturamento TO faturamento;

Elapsed: 00:00:02.03

CREATE TABLE ... AS SELECT (pCTAS)CREATE INDEX

PQ3PQ2PQ1

high-water mark (HWM)

unused space

EXTENT 1 EXTENT 2 EXTENT 3 EXTENT 4 EXTENT 5

TEMPORARYSEGMENT

TEMPORARYSEGMENT

TEMPORARYSEGMENT

TABLESPACE SEGMENT

QC

P003P002P001

PQSlaveProcess

Local(Non/Prefixed, Prefixed)IndexPartitions

Table Partitions

Indexed Range ScanStatic Partitioned TableStatic Partitioned Index

Partitioned Table

CREATE TABLE Vendas(Mes NUMBER(6), Prod_id NUMBER, Loja_id NUMBER, Faturamento NUMBER, Custo NUMBER)STORAGE (...)PARALLEL (DEGREE 8)...

PARTITION BY RANGE (Mes)(PARTITION 01 VALUES LESS THAN (`199901´)

TABLESPACE Vendas_1999Jan,PARTITION 02 VALUES LESS THAN (`199902´)

TABLESPACE Vendas_1999Fev,...PARTITION 12 VALUES LESS THAN (`199912´)

TABLESPACE Vendas_1999Dec );

Partitioned Index

CREATE INDEX Mes-Loja ON Vendas (Mes, Loja_id)STORAGE (...)PARALLEL (DEGREE 8)...LOCAL

(PARTITION I-01 TABLESPACE I_1999Jan, PARTITION I-02 TABLESPACE I_1999Fev, ... PARTITION I-12 TABLESPACE I_1999Dez);

Index Range Scan

SELECT degree FROM user_tablesWHERE table_name = `Vendas´;

DEGREE 8

SELECT Loja_id, SUM(Faturamento)FROM Vendas WHERE Mes IN (`199902´, `199903´, `199904´)GROUP BY Loja_id;

Full Scan em Tabelas Fragmentadas

CREATE INDEX Loja_Mes ON Vendas (Loja_id, Mes)STORAGE (...)PARALLEL (DEGREE 8)...LOCAL

(PARTITION I-01 TABLESPACE I_1999Jan, PARTITION I-02 TABLESPACE I_1999Fev, ... PARTITION I-12 TABLESPACE I_1999Dez);

SELECT COUNT(*) FROM VendasWHERE Loja_id = 08;

PARTITION 3PARTITION 2PARTITION 1

QC

PQ3PQ2PQ1

QUERYQUERYQUERYUPDATE

ORDELETE

UPDATEOR

DELETE

UPDATEOR

DELETE

TABLE X

Indexed Range ScanStatic Partitioned TableStatic Partitioned Index

Consulta em Paralelo

Opção “Parallel Server”

AccountingDepartmentEnd-users

MarketingDepartmentEnd-users

Database Instance 1 Database Instance 2

Node 1 Node 2

Oracle Parallel Server Database

NODE 1 NODE 2 NODE 3

1 32 4 125 87 11106 9PQPQPQPQPQ PQPQPQ PQPQPQPQ

PARALLEL (DEGREE 4 and INSTANCES 3)

Table Full ScanSELECT degree FROM user_tablesWHERE table_name = `Vendas´;

DEGREE INSTANCES 1 1

SELECT COUNT(*)FROM Vendas;

COUNT(*) 12384004Elapsed: 00:58:49.01

SELECT degree, instances FROM user_tablesWHERE table_name = `Vendas´;

DEGREE INSTANCES 4 3

SELECT COUNT(*)FROM Vendas;

COUNT(*) 12384004Elapsed: 00:05:13.23

Parallel Cache Management

Instância A Instância B

2

Oracle Parallel Server Database

Attempt toobtain

EXCLUSIVELOCK

DLM transmitslock attempt to

all maching instances

Parallel Cache Management

Instância A Instância B

1. May Iexclusively

lock thisblock?

1

2

2. First, let mewrite my

changes to thedatafile

3OK, now

you may havethe lock

4

4. Read blockinto cache

Oracle Parallel Server Database

Consulta em Paralelo

BD Distribuído

AccountingDepartmentEnd-users

MarketingDepartmentEnd-users

Database Instance 1 Database Instance 2

Database 1 Database 2

Occasional

Occasional

Transactions

Transactions

Node 1 Node 2

abc

CLIENT

Oracle InstanceLOCL

Oracle InstanceRMOT

Select @RMOTSelect

DATABASE SERVER #2DATABASE SERVER #1

abc

def

A REMOTE QUERY

BD Oracle Distribuído

CREATE [PUBLIC] DATABASE LINK rmotCONNECT TO username IDENTIFIED BY passwordUSING `connect_string´;

CREATE PUBLIC SYNONYM projetosFOR projetos@rmot;

SELECT *FROM projetos;

abd

CLIENT

Oracle InstanceLOCL

Oracle InstanceRMOT

Select @LOCL,@RMOT

Select

DATABASE SERVER #2DATABASE SERVER #1

abc

def

A DISTRIBUTED QUERY

CREATE VIEW todos_os_projetos ASSELECT *

FROM projetosUNION ALLSELECT *

FROM projetos@europaUNION ALL...;

SELECT nome_projeto, data_inicioFROM todos_os_projetos;

BD Oracle Distribuído

Propriedades de uma Transação

• Transação Centralizada• Transação Distribuída• Propriedades ACID

– Atomicidade a Falhas (A)– Consistência (C)– Isolação (I)– Durabilidade (D)

a´b´

CLIENT

Oracle InstanceLOCL

Oracle InstanceRMOT

Update @RMOTUpdate

DATABASE SERVER #2DATABASE SERVER #1

a´b´c

def

A REMOTE TRANSACTION

a´b´d´

CLIENT

Oracle InstanceLOCL

Oracle InstanceRMOT

Update @LOCL,@RMOT

Updade

DATABASE SERVER #2DATABASE SERVER #1

a´b´c

d´ef

A DISTRIBUTED TRANSACTION

Protocolo de Validação de Transações Distribuídas

• Protocolo de Validação em Duas Fases

Standard Distributed Two-Phase Commit Protocol

Coordinator Logic

Local prepare. Invoke each local resource manager to prepare for commit.Distributed prepare. Send a prepare request on each of the transaction’s

outgoing sessions.Decide. If all resource managers vote yes and all outgoing sessions respond yes,

then durably write the transaction commit log record containing a list of participating resource maanagers and transaction managers.

Commit. Invoke each participating resource manager, telling it the commit decision. Send “commit” message on each of the transaction’s outgoing sessions.

Complete. When all local resource managers and all outgoing sessions acknowledge commit, write a completion record to the log indicating that phase 2 completed. When the complete record is durable, deallocate the live transaction state.

Standard Distributed Two-Phase Commit Protocol

Participant Logic

Prepare()Local prepare. Invoke each local resource manager to prepare for commit.Distributed prepare. Send prepare requests on the outgoing sessions.

Decide. If all resource managers vote yes and all outgoing sessions respond yes, then the local node is almost prepared.

Prepared. Durably write the transaction prepare log record containing a list of participating resource managers, participating transaction managers, and the coordinator transaction manager.

Respond. Send yes as response (vote) to the prepare message on the incoming session.

Wait. Wait (forever) for a commit message from coordinator.

Standard Distributed Two-Phase Commit Protocol

Participant Logic

Commit()Commit. Invoke each participating resource manager, telling it the commit decision.Complete. When all local resource managers and all outgoing sessions

acknowledge commit decision, write a completion record to the local log indicating that phase 2 completed.

Acknowledge. When the completion record is durable, send acknowledgement of commit to coordinator and deallocate local transaction state.

Servidores de Transações Distribuídas

• “Middle-tier” de Arquiteturas “Three-tier”• Padrão de Interoperabilibade de Processadores de

Transações Distribuídas– OSI-TP– OSI-CCR– X/Open DTP

• Produtos– Microsoft Transaction Server (MTS)– Enterprise Java Beans (EJB – Sun)

SQLSQLServerServerMSMQMSMQOracleOracle

UNIXUNIXCICS/CICS/IMSIMS

MTSMTSUpdateUpdate

AnalysisAnalysis

QueryQuery

Browsers Clients

PresentationPresentation

IIS/ASPIIS/ASPDCOMDCOM

Presentation

ApplicationLogic

Data andResources

Windows NT ServerWindows NT Server

Conclusões

• Estamos no limiar da explosão do hardware e do software paralelo

• Prepare-se para esta nova etapa da evolução das tecnologias de informática!