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Ingres Version 6.4 An Overview of the 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

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Ingres Version 6.4 An Overview of the Architecture

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

  2. Ingres 6.4 - An Overview • Client / Server Architecture • Components • Locking & I/O • Server Internals • Query Processing

  3. Client - Server Architecture

  4. Client - Server Architecture • User Image • Name Server • DBMS Server • Archiver • Recovery Process

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

  6. Name Server

  7. 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 ?

  8. Name Server - Ingres /Net

  9. DBMS Server • The Ingres “engine” • Accepts incoming SQL • Processes it • Executes I/O on behalf of Users • Multi - threaded

  10. Components

  11. 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

  12. Logging and Recovery (cont)

  13. 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

  14. 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

  15. 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

  16. 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 !

  17. Components

  18. Locking • Initiated by Server Process • Types • Exclusive / Shared • Levels • Page / Table / Database • VMS Cluster • II_CSP talks to clusterwide lock manager

  19. 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

  20. 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

  21. Server Internals

  22. 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)

  23. 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)

  24. 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 !

  25. Conclusions • Ingres DBMS is complex • Multiple Components • Handle with care !!!

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