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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

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ingres 6 4 an overview
Ingres 6.4 - An Overview
  • Client / Server Architecture
  • Components
  • Locking & I/O
  • Server Internals
    • Query Processing
client server architecture1
Client - Server Architecture
  • User Image
  • Name Server
  • DBMS Server
  • Archiver
  • Recovery Process
name server
Name Server
  • isql dbname
    • image activated
    • call Ingres General Communication Facility (GCF) routines
    • opens connection to Name Server
name server2
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 ?
dbms server
DBMS Server
  • The Ingres “engine”
  • Accepts incoming SQL
  • Processes it
  • Executes I/O on behalf of Users
  • Multi - threaded
logging and recovery
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 cont1
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 / 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
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
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 !
locking
Locking
  • Initiated by Server Process
  • Types
    • Exclusive / Shared
  • Levels
    • Page / Table / Database
  • VMS Cluster
    • II_CSP talks to clusterwide lock manager
locking cont
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
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
query processing parsing
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
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
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 user’s front end program !
conclusions
Conclusions
  • Ingres DBMS is complex
  • Multiple Components
  • Handle with care !!!