Ingres 6.4 DBMS Architecture

Ingres Version 6.4 An Overview of the Architecture Presented by Quest Software Ingres 6.4 - An Overview

Client / Server Architecture Components Locking & I/O Server Internals

Query Processing Client - Server Architecture Client - Server Architecture

User Image Name Server DBMS Server Archiver Recovery Process

Name Server isql dbname image activated call Ingres General Communication Facility (GCF) routines opens connection to Name Server

Name Server Name Server Uses GCA Protocol Receives connection request from User Image Provides mailbox address to User User Image Connects to DBMS

What about Ingres / Net ? Name Server - Ingres /Net DBMS Server

The Ingres engine Accepts incoming SQL Processes it Executes I/O on behalf of Users Multi - threaded

Components Logging and Recovery DBMS Server writes to memory log buffers Recovery Process

Reads from memory log buffers Writes to Physical Log File Returns ok to complete to Server DBMS Server writes to the database Logging and Recovery (cont)

Logging and Recovery (cont) Circular Log File All transactions which update the database are logged Writes Before Image to log file Transaction Complete stamp after complete

Write to the log file BEFORE the database Group Commit / Fast Commit Group Commit Sever writes query A to log buffers Sever writes query B to same buffers All commits are written together

Fast Commit Server writes forces directly to Log File then writes to the database (Cached) Write-Behind threads write to the database Archiving Log File has periodic Consistancy

Points Archiver reclaims space from the Log File Only extracts COMMITED transactions from the Log File Writes transactions to the Journals Moves the End Of File marker forward

Archiving (cont) If there are Uncommitted Transactions in the Log File Archiver Process cannot extract them Cannot move the EOF marker Log File Fills Up Chaos !

Components Locking Initiated by Server Process Types Exclusive / Shared Levels

Page / Table / Database VMS Cluster II_CSP talks to clusterwide lock manager Locking (cont) Locking Escallation can Occur when MAXLOCKS exceeded

Locks Per Transaction exceeded Ingres installation-wide resources low Blocking Locks Cause Deadlock checking to start I/O Handling Unix has Synchronous I/O

call iislave processes to offload I/O requests II_NUM_SLAVES how many ? VMS has Asynchronous I/O Server Internals

Query Processing - Parsing Query arrives in Server Control Facility (SCF) Store Text in Query Storage Facility (QSF) Parse the Query (PSF) Check the Relational Descriptions (RDF)

Check Query Modifications due to Permits, Views etc. (QRYMOD) Query Processing - Planning Create a Parsed Query Tree in QSF Optimiser (OPF) uses Query Tree & Statistics to develop Query Plan Store the Query Plan in QSF

Query Execution Facility validates table descriptions (QEF) Query Processing - Execution Access the actual files using the Data Manipulation Facility (DMF) DMF returns data to QEF QEF returns data to SCF

SCF returns data to GCA communications Eventually ends up at the users front end program ! Conclusions Ingres DBMS is complex Multiple Components

Handle with care !!!