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John Kanagaraj, DB Soft Inc Expert Session #319 (2 hour)

ORACLE DATABASE 10GR2: AN ENLIGHTENED REVISIT (BEFORE WE GIVE UP AND MOVE TO 11G!). John Kanagaraj, DB Soft Inc Expert Session #319 (2 hour). Speaker Qualifications. John is a Principal Consultant @ DB Soft Inc. Executive Editor for IOUG’s SELECT Journal

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John Kanagaraj, DB Soft Inc Expert Session #319 (2 hour)

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  1. ORACLE DATABASE 10GR2: AN ENLIGHTENED REVISIT (BEFORE WE GIVE UP AND MOVE TO 11G!) John Kanagaraj, DB Soft IncExpert Session #319 (2 hour)

  2. Speaker Qualifications • John is a Principal Consultant @ DB Soft Inc. • Executive Editor for IOUG’s SELECT Journal • Co-author of “Oracle Database 10g Insider Solutions” • Technical Editor for various books • Frequent presenter – IOUG/OAUG/OOW/NoCOUG • Published in SELECT, OAUG Insight, SQL Server Magazine and other publications • Recognized by Oracle Corp as an “Oracle ACE”

  3. SELECT: Call for Articles/Reviewers • The SELECT Journal is IOUG’s Technical Quarterly • Distributed to all IOUG members worldwide • Yearly Best Practices and Tips booklet • Submit an article or Review one! • Contact ‘select@ioug.org’

  4. What this presentation is about • Oracle Database 10g now in “full production” mode • R1 released in 2003 (?), R2 in 2005 (?) • A little history lesson – book, papers • Lead time between books/initial articles and “consolidation” / “better understanding” • Need to revisit and update the “first revelation” • Reconsider “new features” – fresh look • Hidden surprises and little bonuses • A peek into the future – 11g titbits

  5. Audience survey • Using Oracle Database 11g in production? • Still using Oracle 7 or 8i? • Migrating to Oracle Database 10g? • Read the “New features” manual for every release? • Used Advisories in 9i? • Used Active Session History for troubleshooting? • Read AWR/ADDM/ASH reports? • Used SQL Profiles to fix SQL issues?

  6. Overview of new perf features • Strictly related to performance related features • Need to “unlearn the old and embrace the new” • AWR – The Performance Warehouse • ASH – What happened to the sessions?!? • ADDM – Your inbuilt (and unpaid!) expert • Tuning advisors – Bonus freebies • In-Memory metrics and Server generated alerts • Where to look for more details

  7. Philosophy behind Oracle DB 10g • Automation • Incremental steps in 9i (Advisors, Time) • Most significant change in Performance management • “Out of the box” setups • GUI “hides” the complexity (and details!) • Consistency • Common/Unified interface • Stats storage and presentation • Interpretation

  8. Reality check before we proceed • Licensing changes in Oracle Database 10g • A tale of two packs: • Oracle Diagnostic Pack • Automatic Workload Repository (AWR) • Automatic Database Diagnostic Monitor (ADDM) • Monitoring and Event notifications and history • Oracle Tuning Pack • SQL Access Advisor • SQL Tuning Advisor and STS • Object Advisor • Required even to access Views directly!!!

  9. AWR – Performance Warehouse • Performance Data Warehouse for 10g • Basis for most of the problem detection and reporting • AWR collects, stores performance data • Direct memory access (MMNL/MMON) • In-memory component (V$/Metric views) • “Persisted” in WR tables (SYSAUX) • 162 tables – WRI$, WRH$, WRM$ • Exposed via DBA_HIST_* Views • Self managing “out of the box” • Set retention, frequency, baseline

  10. AWR Contents • Active Session History (ASH) • High-load SQL statements • Time model statistics (both System/Session) • Object usage - access counts for segments • Snapshots of V$ and some Metrics • Host CPU and Memory statistics (V$OSSTAT) • Baseline information • “Management” type information • Snapshot details • Advisor and other parameters

  11. AWR – “Statspack on Steroids” • Similar to STATSPACK “snapshots” • Reportable – AWRRPT.SQL • AWR snapshot automatically analyzed • Accessible via GUI and API/SQL (*) • High-impact SQL captured differently • Stores session level info as well * Read the fine print : License required, even for SQL access!

  12. AWR Baselining and comparison • Enables performance “baselining” • Collection of two or more snapshots • Stored in “_BL” tables; data not purged • View using WRM$_BASELINE/DBA_HIST_BASELINE • Reports diff via AWRDDRPT.SQL • Execution statistics for specific SQL statement using AWRSQRPT.SQL

  13. ASH – What’s up with sessions • Historical view of active sessions • Active sessions sampled every second • Stored in circular memory buffer • Every 10th sample persisted in AWR • V$ACTIVE_SESSION_HISTORY : “In-memory” • WRH$_ACTIVE_SESSION_HISTORY : “Persisted” • Enables “after-the-fact” analysis!!! • Reported via ASHRPT (Not available in 10gR1) • “Slice-and-dice” analysis can reveal a lot of info

  14. ASH – Session states exposed! • “On-the-spot” analysis • Retroactive analysis • From memory buffer (V$ACTIVE_SESSION_HISTORY) • From persisted AWR data (WRH$_ACTIVE_SESSION_HISTORY connected via SNAP_ID) • Supports manual drill down from AWR/ADDM • Tracks High load SQL execution behavior • Determine Blocking sessions and “hot” segments • SESSION_STATE : “ON CPU” or “WAITING”

  15. ADDM – Your unpaid Tuning Expert! • Starting point for most investigations • Runs after every AWR snapshot • Determines and records performance issue • Recommends corrective action • Generates probable benefit • Suggest use of other advisors • Common currency - “DB Time” (qualitative!) • Oracle DB 11g – new “Instance ADDM”

  16. ADDM – Partial check list • CPU bottlenecks • Excessive parsing • Lock contention • Concurrency • I/O capacity • Incorrect sizing of Oracle memory and file structures • High-load SQL, Java and PL/SQL statements • Poor connection management • Hot objects • RAC-specific issues

  17. ADDM – Findings/Recommendations • Qualitative rather than Quantitative analysis • Hardware changes • Database-configuration changes • Schema-level changes • Application changes • Using other advisors (for example) • SQL Tuning Advisor / SQL Access Advisor • Segment Advisor • Don’t stare at the screen – Use SQL to summarize • Details in my 2007 paper

  18. Advisors – A step beyond • Builds on 9i advisors • Buffer cache advisor • Shared pool advisor • MTTR (Mean Time To Recover) advisor • Summary (MVIEW) advisor • PGA Target Advisor • New in 10g • SQL Tuning Advisor • SQL Access Advisor • Segment Advisor

  19. SQL Tuning Advisor • Frontend to Automatic Tuning Optimizer • Extension (reuse) of Optimizer (CBO) • Performs “what-if” analysis • Not restricted by “time to optimize” (_optimizer_max_permutations = 2000) • The following advice is provided • Gather missing or stale statistics • Create new indexes • Restructure SQL statement • SQL profiles

  20. SQL Tuning Advisor • SQL Profile • Collects additional information via sampling/partial execution techniques • Verifies and adjusts CBO’s estimates at runtime • Similar in function to Outlines • Enabled by category : “test-and-set” • Access/manipulate – DBMS_SQLTUNE • Precedence given to Stored Outlines • Runs against individual SQL or SQL Tuning Sets (STS)

  21. Other Advisors • SQL Access Advisor • Works alongside SQL Tuning Advisor • Advice on MV, Indexes, MV logs • Considers space usage vs performance • Inputs: STS, User-defined, Hypothetical • Advanced: Workload type (RO), Drop unused indexes, Filters (Top N, Module) • Segment Advisor • Undo Advisor • Memory Advisor • Metrics and Server Generated Alerts

  22. Avoiding Advisor Pitfalls • Out-of-the-box thinking (redesign; rethink approach) • False positives (check validity for all situations – e.g. Index non-usage) • Changing workload or environment (additional load, new code, H/W or S/W changes)

  23. Features revisited • STATSPACK – Not dead yet! • New and changed views – tons of goodies! • Event Breakout – Greater visibility • Mutexes – Boon or Bane? • Operating System Statistics – all in one place • Time and Wait Model – aids better understanding • Hidden Surprises – watch out! • Useful AWR sections – Segstats and much more • Extracting Data from AWR – Drill down example • DBMS_XPLAN – in-depth view

  24. STATSPACK – Not dead yet! • STATSPACK is still available in Oracle DB 10g • No license required to track performance stats • Setup/maintenance/reporting : same as before • Default is Level 5, set at Level 7 to get Segment stats • Number of new sections available • OS Statistics • DB Time reporting • Response time Histograms (Event, File and Temp) • Additional SQL sections in Report • Comparison to AWR • Check Metalink Note: 394937.1 (incomplete)

  25. STATSPACK – Host Statistics Host CPU (CPUs: 32) ~~~~~~~~ Load Average Begin End User System Idle WIO WCPU ------- ------- ------- ------- ------- ------- -------- 0.04 0.03 3.38 1.06 95.56 3.13 ####### Instance CPU ~~~~~~~~~~~~ % of total CPU for Instance: 3.64 % of busy CPU for Instance: 81.90 %DB time waiting for CPU - Resource Mgr: Memory Statistics Begin End ~~~~~~~~~~~~~~~~~ ------------ ------------ Host Mem (MB): 65,274.7 65,274.7 SGA use (MB): 6,144.0 6,144.0 PGA use (MB): 2,038.8 2,233.6 % Host Mem used for SGA+PGA: 12.5 12.8 -------------------------------------------------------------

  26. STATSPACK – Host Statistics • Calculation of Total and Busy CPU (spcpkg.sql) % of total CPU for Instance:' ch45n, 100* ((:dbcpu+:bgcpu)/1000000) / (:ttics) pctval % of busy CPU for Instance:' ch45n, 100* ((:dbcpu+:bgcpu)/1000000) / ((:btic)/100) pctval • Available in Time Model (V$SYS_TIME_MODEL) • Discrepancy between estimated and actual CPU • (Busy_Time + Idle_Time) vs. (No.of.secs * No. of CPUs) • Usually present when load is high (queue depth/wait for CPU) • Note memory statistics – tracked in V$OSSTAT • This section not reported in AWR Report!!!

  27. STATSPACK – Response Histograms Wait Event Histogram DB/Inst: MYRAC/MYRAC1 Snaps: begin_snap-end_snap -> Total Waits - units: K is 1000, M is 1000000, G is 1000000000 -> % of Waits - column heading: <=1s is truly <1024ms, >1s is truly >=1024ms -> % of Waits - value: .0 indicates value was &lt.05%, null is truly 0 -> Ordered by Event (idle events last) Total ----------------- % of Waits ------------------ Event Waits <1ms <2ms <4ms <8ms <16ms <32ms <=1s >1s -------------------------- ----- ----- ----- ----- ----- ----- ----- ----- ----- enq: TX - row lock content 7561 4.1 .0 .0 .1 .1 95.8 enq: WF - contention 7 57.1 42.9 enq: WL - contention 4 75.0 25.0 gc buffer busy 1893 74.2 4.5 3.4 11.5 3.4 1.2 1.7 gc cr block busy 33K 21.9 8.4 3.5 5.0 5.0 27.3 28.7 gc cr block congested 117 3.4 23.1 53.8 18.8 .9 gc cr disk read 1626 99.6 .4 .1 gc cr failure 1 100.0 <snip> SQL*Net break/reset to cli 2276 99.3 .5 .1 .2 SQL*Net message from dblin 683 43.6 25.0 14.5 4.2 6.4 2.0 4.1 SQL*Net message to dblink 683 100.0 <snip> db file scattered read 2070K 91.4 7.3 .7 .5 .1 .0 .0 db file sequential read 1413K 96.4 1.2 .6 1.5 .3 .0 .0

  28. STATSPACK – Response Histograms • Response Time Histograms • Snapped for Event, File and Temp • V$EVENT_HISTOGRAM • V$FILE_HISTOGRAM • V$TEMP_HISTOGRAM • Helpful in seeing spread, bumps in wait events • Troubleshooting network response (example later) • SQL*Net break/reset to client - Client traffic • SQL*Net message to client (and “to dblink”) – Inter server • gc cr block congested (Internode traffic) – Intra instance • Not present in AWR (neither snapped or reported)

  29. STATSPACK – New SQL sections • New SQL reporting sections in Oracle DB 10g SP • SQL ordered by CPU : From CPU_TIME in V$SQL • SQL ordered by Elapsed: From ELAPSED_TIME in V$SQL • SQL ordered by Cluster Wait Time: From new CLUSTER_WAIT_TIME in 10g V$SQL • Report compares total time for SQL statements captured to total time reported in the DB SQL ordered by CPU DB/Inst: MYRAC/MYRAC1 Snaps: begin_snap-end_snap -> Resources reported for PL/SQL code includes the resources used by all SQL statements called by the code. -> Total DB CPU (s): 1,826 -> Captured SQL accounts for 202.4% of Total DB CPU -> SQL reported below exceeded 1.0% of Total DB CPU CPU CPU per Elapsd Time (s) Executions Exec (s) %Total Time (s) Buffer Gets ---------- ------------ ---------- ------ ---------- --------------- 947.13 437 2.17 51.9 3503.86 29,619,674 select q_name, state, delay, expiration, rowid, msgid, dequeue _msgid, chain_no, local_order_no, enq_time, enq_tid, step_no,

  30. New and changed views • Large number of new as well as changed views • (Sometimes) Inadequate documentation, but powerful uses! • Classified by • Services related • In-memory metrics • Response Histograms • Extensions to existing views • Interesting views • Common columns

  31. Service related views • “Service” concept created in Oracle 8.0 • Provides ability to connection to an abstract entity • SERVICE_NAME column in various views • New views • V$SERVICES : Services description (failover and load balancing information included) • V$SERVICE_STATS : Workload statistics • V$SERVICE_EVENT : Events by service

  32. Service related views SQL> select name, goal, dtp, aq_ha_notification, clb_goal 2* from v$services; NAME GOAL D AQ_HA_NOTIFICATION CLB_GOAL -------------------- ---------- - ------------------ ---------- APPLSYS.WF_CONTROL NONE N NO LONG MYRAC1.MYDOM.COM NONE N NO LONG SYS$BACKGROUND NONE N NO SHORT SYS$USERS NONE N NO SHORT SQL> select service_name, stat_name, value 2 from v$service_stats 3 where stat_name in 4 ('cluster wait time','db block changes'); -- among 28 different stats SERVICE_NAME STAT_NAME VALUE -------------------- ------------------------------ ---------------- SYS$USERS db block changes 34,618,836 MYRAC1.MYDOM.COM db block changes 471,456,178 APPLSYS.WF_CONTROL db block changes 0 SYS$BACKGROUND db block changes 2,383,337 SYS$USERS cluster wait time 52,810,072,281 MYRAC1.MYDOM.COM cluster wait time 798,080,328,466 APPLSYS.WF_CONTROL cluster wait time 0 SYS$BACKGROUND cluster wait time 4,405,806,181

  33. Service related views SQL> select service_name, event, total_waits, 2 total_timeouts, time_waited 3 from v$service_event 4 where event in ( 5 'latch: library cache', 'read by other session'); -- from 114 events SERVICE_NAME EVENT TOTAL_WAITS TIMEOUTS TIME_WAITED ---------------- --------------------- ----------- -------- ----------- MYRAC1.MYDOM.COM read by other session 25107023 23985 10848655 MYRAC1.MYDOM.COM latch: library cache 420975 0 4352231 SYS$BACKGROUND read by other session 29 0 14 SYS$BACKGROUND latch: library cache 6742 0 104454 SYS$USERS read by other session 27368974 435 3657701 SYS$USERS latch: library cache 144347 0 734451 • Ability to segment and measure workload • Needs to be setup (becomes complex in RAC environments)

  34. In-memory metrics • V$METRIC/V$SYSMETRIC (V$SYSSTAT) -> V$SYSMETRIC_HISTORY • V$EVENTMETRIC (V$SYSTEM_EVENT) -> V$EVENT_METRIC_HISTORY • V$SYSMETRIC_SUMMARY (Avg/Min/StDev) • WRH$_SYSMETRIC_SUMMARY • V$METRICNAME / V$METRICGROUP • Metrics -> Rate of change of statistics counters • Alerts on rate -> Server Generated Alerts (changeable via EM) • Short-lived (3 mins of 15 secs, 1 hr of 60 secs)

  35. In-memory metrics SQL> select event, wait_time_milli, wait_count 2 from v$event_histogram 3* where event like 'SQL*Net %to client' EVENT WAIT_TIME_MILLI WAIT_COUNT ------------------------------ --------------- ---------- SQL*Net message to client 1 137034612 SQL*Net message to client 2 19183 SQL*Net message to client 4 9922 SQL*Net message to client 8 5446 SQL*Net message to client 16 2931 SQL*Net message to client 32 1519 SQL*Net message to client 64 752 SQL*Net message to client 128 310 SQL*Net message to client 256 111 SQL*Net message to client 512 29 SQL*Net message to client 1024 1 SQL*Net message to client 2048 1 SQL*Net more data to client 1 8582781 SQL*Net more data to client 2 34556 SQL*Net more data to client 4 22114 SQL*Net more data to client 8 20108

  36. Existing/New views • Number of existing views expanded • V$SQL, V$SESSION • Information merged from various views • V$SESSION (V$SESSION_WAIT and V$LOCK) • New visibility • V$SQL_BIND_CAPTURE • V$SQL_SHARED_CURSOR • Common Columns • WAIT_CLASS and related • WRH Tables exposed via DBA_HIST_% views • V$PROCESS_MEMORY – session wise memory • V$SQLSTATS – Low overhead access

  37. V$SESSION view • Wait information merged from V$SESSION_WAIT • EVENT, P1 – P3, SEQ#, WAIT_CLASS • Lock information from V$LOCK • BLOCKING_SESSION, BLOCKING_SESSION_STATUS, BLOCKING_INSTANCE • Tons of new columns • SQL_ID (Current and Previous) • SQL_CHILD_NUMBER (Current and Previous) • PLSQL related information (Entry, Subprogram, Object, etc) • SQL_TRACE columns (binds and waits as well) • CLIENT_IDENTIFIER (DBMS_MONITOR) • No need to join to V$SESSION_WAIT, V$LOCK now

  38. V$SQL view • Complete text in SQL_FULLTEXT • Parallel execution (PX_SERVERS_EXECUTION) • Different types of wait times • APPLICATION_WAIT_TIME • CONCURRENCY_WAIT_TIME • CLUSTER_WAIT_TIME • USER_IO_WAIT_TIME • PLSQL_EXEC_TIME • JAVA_EXEC_TIME • Additional details: • PARSING_SCHEMA_NAME • Optimizer details • BIND_DATA • LAST_LOAD_TIME (Docs: LAST_ACTIVE_TIME??)

  39. V$SQL related views • V$SQL_OPTIMIZER_VIEW • Optimizer parameters for SQL_ID and particular child cursor • V$SQL_PLAN • TIMESTAMP, OTHER_XML, QBLOCK_NAME, etc. • DBMS_XPLAN exposes details* • V$SQL_SHARED_CURSOR • Why was a cursor not shared? • USER_BIND_PEEK_MISMATCH column • Groundwork for 11g bind-awareness/bind-sensitiveness • V$SQL_BIND_CAPTURE • Use with ASH to get some bind values * Undocumented : “ADVANCED” parameter to get OTHER_XML details

  40. Event Breakout • Event names for “blocking” type events changed • “latch free” now has 29 types (10.2.0.3) • latch: cache buffers chains • latch: library cache • latch: library cache pin • “enqueue” has 205 types (10.2.0.3) • enq: TX - row lock contention (Waiting for Row lock) • enq: UL – contention (Waiting for User generated lock) • enq: XR - quiesce database (Waiting for DB Quiesce) • enq: ST – contention (Space transaction – rare now with LMT) • “read by other session” (BBW with reason code 130) • Break out at all levels (session/system- compare R1) • Major change in monitoring / reporting code!!!

  41. Mutexes – Boon or Bane? • Low overhead mechanism replacing some latches • “Simulated” on certain platforms • HP-UX uses a CAS (“compare-and-swap”) simulator • This itself is a latch: quite an overhead • Track using V$MUTEX_SLEEP and V$MUTEX_SLEEP_HISTORY • “_kks_use_mutex_pin = FALSE” turns this off • Snapshotted in STATSPACK, not in AWR 

  42. Operating System Statistics • Set SQL*Plus format to get right value! (issue in AWR) SQL> select stat_name, value 2 from v$osstat; STAT_NAME VALUE ---------------------------------------------------------------- ---------- NUM_CPUS 24 IDLE_TIME 802033123 BUSY_TIME 878091185 USER_TIME 489231709 SYS_TIME 388859476 IOWAIT_TIME 187539358 AVG_IDLE_TIME 33398667 AVG_BUSY_TIME 36564711 AVG_USER_TIME 20362160 AVG_SYS_TIME 16180042 AVG_IOWAIT_TIME 7794964 OS_CPU_WAIT_TIME 2.6867E+13 RSRC_MGR_CPU_WAIT_TIME 0 LOAD 2.359375 NUM_CPU_SOCKETS 24 PHYSICAL_MEMORY_BYTES 1.0287E+11 VM_IN_BYTES 7868502024 VM_OUT_BYTES 0

  43. Time Model • CPU breakup; updated every 3 seconds!!! SQL> select stat_name, value from v$sys_time_model where value > 0; STAT_NAME VALUE --------------------------------------------- -------------- DB time 893170091346 DB CPU 176244910473 sequence load elapsed time 10215471781 parse time elapsed 4524012412 hard parse elapsed time 3657262901 failed parse elapsed time 103540062 hard parse (sharing criteria) elapsed time 365217641 hard parse (bind mismatch) elapsed time 5923514 repeated bind elapsed time 14768010 connection management call elapsed time 328536127 PL/SQL execution elapsed time 5554924592 PL/SQL compilation elapsed time 333815896 background elapsed time 13782131027 background cpu time 4572399582

  44. Wait Model SQL> select wait_class, time_waited, total_waits from v$system_wait_class; WAIT_CLASS TIME_WAITED TOTAL_WAITS -------------------- ---------------- ---------------- Other 1370371162 10777690366 Application 11031616 77468 Configuration 433075 3972043 Administrative 986 10 Concurrency 5069513044 4023651698 Commit 4187059 4606985 Idle 26816217176 1179884266 Network 1964510 152943745 User I/O 845512795 3197266600 System I/O 21813081 47778673

  45. Wait Class • Types of wait: classified by WAIT_CLASS SQL> select wait_class, count(*) from v$event_name 2 group by wait_class; WAIT_CLASS COUNT(*) ----------------- ----- User I/O 17 Application 12 Network 27 Concurrency 25 Administrative 46 Configuration 23 Scheduler 2 Cluster 47 Other 592 Idle 62 System I/O 24

  46. Hidden surprises • GROUP BY does not ensure ORDER BY • New code base avoids sort for GROUP BY operation • Order was never guaranteed • Large amount of legacy/custom code needs change • Investigate “_gby_hash_aggregation_enabled” parameter • System Statistics • “CPU Cost” optional in 9i • Fully functional (by default) in 10g • Sample collected when DB installed/upgraded • Check in SYS.AUX_STATS$ view • See Metalink Notes: 457228.1, 153761.1, 149560.1 • Collecting System Stats does NOT invalidate shared pool

  47. Hidden surprises • Dynamic sampling • 9i default was 1 • 10g default is 2 • all unanalyzed tables are sampled • Number of blocks sampled: twice default number (2x32=64) • Impact on Global Temp tables • Impact on parse (not affected by plan permutation limits) • Statistics gathering and Table monitoring • Monitoring ON by default • Used by Automatic Stats gathering (Dictionary stats included) • Trigger fixed at 10%, changeable in 11g • Stats collection for Fixed table (new but optional)

  48. Hidden surprises • DBMS_STATS • 9i and below: Defaults were fixed • 10g and above: Defaults can be changed (boon or bane?) • Many parameters default to “decided by Oracle” • Examples: • NO_INVALIDATE: DBMS_STATS.AUTO_INVALIDATE • CASCADE: DBMS_STATS.AUTO_CASCADE • ESTIMATE_PERCENT: DBMS_STATS.AUTO_SAMPLE_SIZE • METHOD_OPT: FOR ALL COLUMNS SIZE AUTO • GRANULARITY: AUTO (For partitioned objects only) • Automatically stores past 31 days DBA_TAB_STATS_HISTORY • DIFF_TABLE_STATS_* function in 10.2.0.4

  49. Useful sections: AWR Report • Segment statistics in AWR report • Same as “Top 5 Segments” in Level 7 STATSPACK reports (9i+) • Segments by Global Cache Buffer Busy (RAC only, new section in 10g) • Segments by CR Blocks Received (RAC only) • Segments by Current Blocks Received (RAC only) • New GC Load profile and GC Efficiency percentages Global Cache Load Profile ~~~~~~~~~~~~~~~~~~~~~~~~~ Per Second Per Transaction --------------- --------------- Global Cache blocks received: 1,375.70 2.90 Global Cache blocks served: 164.77 0.35 GCS/GES messages received: 5,165.31 10.88 GCS/GES messages sent: 8,684.54 18.30 DBWR Fusion writes: 0.63 0.00 Estd Interconnect traffic (KB) 15,028.80 Global Cache Efficiency Percentages (Target local+remote 100%) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Buffer access - local cache %: 97.41 Buffer access - remote cache %: 0.43 Buffer access - disk %: 2.16

  50. Extracting data from the AWR • Complete source in paper • Adaptable for different types of extracts /* This cursor fetches details of the current snapshot plus the next one using the LEAD function. We will use this to make sure that there was no DB restart in-between */ cursor snapshot is select snap_id, lead(snap_id, 1, 0) OVER (ORDER BY snap_id), startup_time, lead(startup_time, 1) OVER (ORDER BY snap_id), to_char(begin_interval_time) begin_interval_time, to_char(end_interval_time) end_interval_time from sys.dba_hist_snapshot where instance_number = v_instance_number -- For RAC instances and dbid = (select dbid from v$database);

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