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Brown Bag. Exadata Distinctives. New features for tuning Oracle database applications. What is Exadata?. Complete Oracle database server Disk storage system CPU, memory, network hardware Operating system Database software Fully installed and configured. Cell Storage servers - PowerPoint PPT Presentation

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  • Exadata DistinctivesBrown BagNew features for tuning Oracle database applications

  • What is Exadata?Complete Oracle database serverDisk storage system CPU, memory, network hardwareOperating systemDatabase softwareFully installed and configured

  • Cell Storage serversIntel-based Linux serverswith disk drives

    14 cell servers per rack7 on top, 7 on bottom12 disks per server

  • 8 Intel Linux database servers4 on bottom, 4 on top

    3 Infiniband network switches1 on top, 2 on bottom

  • What is standard about Exadata?Off the shelf hardwareIntel x86 processorsStandard Sun disk drives, memoryInfiniband network adapters and switchesLinux operating systemOracle 11gR2 database software

  • What is unique about Exadata?Storage Servers have Oracle database specific featuresSmart Scan returns only needed dataStorage Indexes only accesses needed disk blocksHybrid Columnar Compression fits data into fewer disk blocks

  • Comparison of three db server typesCompare three types of database servers to demonstrate features unique to ExadataDB server with directly attached disk drivesDB server attached to a Storage Area Network (SAN)ExadataWith Smart ScanWithout Smart Scan

  • Rows, Columns, and BlocksA SQL table is a collection of rows one row per saleA row is a list of columns date, product, customer, amount,A table is broken up into equal sized blocks each with a number of rows = block size/row size = 8000 bytes/80 bytes = 100 rows per blockResults of queries are a subset of the columns and a subset of the rows of a table

  • Title

    MEMORY CACHE

    INDEXES

    USER

    BLOCKS

    RESULTS

    DATABASE SERVER

    DISKS

    COMPRESSION

    Database Server with Just Disks

  • Title

    MEMORY CACHE

    INDEXES

    USER

    BLOCKS

    BLOCKS

    Disk Array (e.g. XP 24000)

    DISKS

    COMPRESSION

    MEMORY CACHE

    RESULTS

    Database Server

    NETWORK

    Database Server with SAN

  • Title

    MEMORY CACHE

    INDEXES

    USER

    BLOCKS

    COMPRESSION

    Cell Storage Server

    DISKS

    RESULTS

    Database Server

    NETWORK

    Exadata with Smart Scan

  • Title

    MEMORY CACHE

    INDEXES

    USER

    BLOCKS

    BLOCKS

    Cell Storage Server

    DISKS

    COMPRESSION

    MEMORY CACHE

    RESULTS

    Database Server

    NETWORK

    Exadata without Smart Scan

  • Observations about the three server typesDB server with disks looks like Exadata Cell serverIndexesCompressionmemory cachereturns small subset of full dataDB server with SAN looks like full Exadata systemStorage serverHigh speed networkDatabase servers

  • More observations about the three server typesDB server with SAN differs from full Exadata systemFull database blocks copied over SAN networkResults only copied over Exadata networkDatabase server caches blocks from SANDatabase server does not cache results from cell serverExadata Smart Scan can be turned offWithout Smart Scan Exadata works just like DB server with SAN

  • How to Use Exadata Smart ScanQueries with full table scans automatically do Smart ScansDrop indexesMake indexes invisibleIncrease optimizer_index_cost_adj to discourage index useUse FULL hints to force full scans

  • How to avoid Smart ScanAdd indexes and verify that plan uses themAdd INDEX hint to force index useSet CELL_OFFLOAD_PROCESSING to FALSEalter system set CELL_OFFLOAD_PROCESSING=FALSE;alter session set CELL_OFFLOAD_PROCESSING=FALSE;hint - OPT_PARAM('cell_offload_processing' 'false')

  • Moving an existing application to ExadataTry these options and see which is faster:Indexes visible or invisibleoptimizer_index_cost_adj normal (100) or high (> 100)CELL_OFFLOAD_PROCESSING=FALSE or TRUEAll of these options can be tested without changing the application

  • Why use Exadata?New set of performance enhancing featuresAll other Oracle features still availableEasy to use new featuresEasy to bypass new features

  • Things to watch out forFlash memory (storage server cache) slowNormal RAM 1000x faster than diskCell server cache (Flash) 10x faster than diskCant control, no documentation for storage indexesWhat columns are they on?What column types can they be on?

  • Things to watch out for page 2Databases tuned for Exadata are not portableDatafiles with HCC wont work on non-Exadata systemApplications that have been tuned to work well on Exadata will be slow on non-ExadataPoor performance of TEMP spaceLike all RAC systems with many nodes moving temp space from node to node kills performance. Newer X2-8 may address this 2 node RAC

  • Things to watch out for page 3HCC and tables > 255 columns buggyWrong results, errorsWrong optimizer statsNewness issuesBugs, hangs, crashes, unexpected resultsLack of documentationLack of trained people

  • RecommendationsSmall number of RAC nodes 2 if possibleUse as few new features as possibleFewer than 256 columns per tableGet Exadata VM from Oracle for sandboxExalogic can connect to DB via InfinibandSwitch our DB links to IB

    What is Exadata and what is unique about it?One Stop Shop everything from Oracle Like IBM mainframe of oldEach cell server takes up 3 rows on the rack. It has three rows of four disks each. Is a Linux server with bunch of disks. One small green light per disk, one large green light per server. 7 servers in this picture top of rack.Just above/below the cell servers are the database servers. Each takes up 2 units or rows of the rack. Has some disk space for O/S and misc use. The first thing above the db servers are the Infiniband switches. Looks like each two unit enclosure holds 2 IB switches. I know there are three IB switches total. From the green lights it looks like two switches on the bottom and one on top. The extra on the bottom should be the spine switch for connecting to the second rack. Have to have two other switches for redundancy. I think there is space for a forth IB switch for further expansion. Also, looking at the green lights on the DB servers looks like they have four disk drives active with empty slots for more. Dark space is where a console pulls out. On db servers one big green light per server, four little green lights for the disks.Can buy hardware, os, database separately theoretically could reconfigure as standard Oracle database server(s) with RACstorage servers = cell servers disk I/O subsystem like SAN. These are the three main PERFORMANCE featuresDemonstrate what is different about Exadata and what is not by comparing it to two other types of Oracle database servers. Compare/contrast.blocks read from disk to memory and copied across san have unneeded rows and columns. Results can be small subset of entire table or full copy of table.Similarity between this and cell server. In this case the indexes and compression operate at the database level. Red is bad entire blocks copied. Green is good small result set. Indexes reduce disk blocks read from disk. Compression fits more rows per block.here the SAN looks like a cell server but there are no indexes, compression and the full blocks are copied over the SAN. SAN cache is like DB cache caches blocksSimilar to the san in that the disks and db server are separate but the database like processing is in the cell. But then what about the DB server? Hash and sort areas would be good to show. Also, can mix both methods. Talk here about increasing hash and sort area size for OBIA but leaving buffer cache small. Explain PGA and SGA? Results go to PGA which is where hashing and sorting caching is.Just like with SAN.Dont flip back to picture. cell server is a database of its own but not standard oracle really different indexes, compressionkey point is blocks copied over fiber network for SAN versus results over infiniband for Exa. Last part leads to how to turn on off Smart scan. key point of smart scan slides.Easy to use smart scan. just do a full scan if you have exadata. these are just ways of doing full scansEither cause index to be used or use parameter. With parameter full scans are no longer smart scans. Regular full scans can be faster when you really want all rows and all columns.Load application on Exadata unchanged and try these three options without changing app. OBIA example for first two. Stats full for third.New tools for our toolbag

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