9/8/2010. Major Points. Temporal - time, portion of time, time based. Time - Includes Times, Dates and Timestamps

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1 Major Points Data Concepts Deficient Models Exploiting Data DB2 10 Versioned Data Roadmap Future of Data - time, portion of time, time based Time - Includes Times, Dates and Timestamps Date Examples - Timestamps Use Same Principles Operational Design Warehouse Different c Ability to Answer Point In Time Questions Provide Historical Perspective Regulatory Compliance Global Enterprises Data Research Warehousing Move Towards 6 th Normal Form (Dimensional Data) Snapshot A table that does not support time based queries A table that supports time based queries 1

2 Snapshot whose data is current Snapshot Snapshot s that can be queried to a point in time s D_STAR D_END s Event s Dimensional s TIME hour, minute, second DATE year, month, day, day of week, Julian TIMESTAMP all of the above & microseconds Simple SQL Knowledge Defined in DB Structure Time Filtering Based on Columns Can Exploit Indexes No Additional Joins Single Row Answer 2

3 No end time (when trying to represent intervals) Use TIME & DATE rather than TIMESTAMP Replicate all rows each cycle Time not in index design Requires non-temporal columns Requires additional rows Pros Easy Provides interval snapshot Cons Not granular Multiple tables or partitions Outages to load & slow Massive data duplication Disk Pros All entries for each date Simple SQL Rows Day 1 Day 2 Day 3 Changed Rows Cons Disk growth Scalability Performance Mass inserts Manageability challenges Massive data duplication Cyclic granularity 16 M 32 M 48 M Big!!! Gap Overlap Pros Saves Disk Cons Inability to handle gaps Inability to represent overlaps Inability to close rows May require non-temporal columns Requires more complex SQL Answer requires multiple rows Open ed Close ed Open ed 3

4 Pros Event oriented Provides timing & sequence Easily indexed Cons Doesn t handle intervals May be selective events Code trigger or application Disk Event I_EVNT,D_EVNT,C_EVNT Pros SQL features simple SQL SQL solely temporal columns Efficient & indexable High performance retrieval Allows or disallows overlaps Allows gaps & closed series Saves Disk Cons Application maintained/enforced Must manage series of rows Must adjust D_END when updating Restricted deleting,m_pric Snapshot,M_PRIC Row,M_PRIC Rows Series Open ed Simple SQL Indexable SQL Application unique key enforcement Date columns placement in Index Index Snapshot vs. Index Snapshot,M_PRIC Index M_PRIC FROM TABLE = :pi Gap Open ed Specific Closed Open ed Overlap M_PRIC FROM TABLE ( = :pi AND( D_STAR >= :cd AND D_END <= :cd )) Index,M_PRIC Ability to get point in time result Support start & end time in each row Ability to allow or prevent gaps Ability to allow or prevent overlaps Ability to close rows Use only temporal columns to qualify SQL Supports native date/time math Read biased 4

5 Define D_STAR and D_END Key Order Uniqueness Constraints RI Constraints Insert / Update / Delete Rules Physical Deletes Single Unit of Work Design Enforcement - Application, Triggers or DB 2/28/ /01/2009 9/30/ /1/2009 1/1/2009 9/1/ /1/2009 1/22/2009 9/30/ /1/2009 Options Rules Allow Gaps Yes Allow Overlaps No Allow Closeouts Yes Physical Deletes No Uniqueness Enforcement Application Design Enforcement Application Low Date Default Current Date High Date Default 12/31/2009 Don t know until after existence check 1) Select Current Row Get keys, D_STAR & D_END 06/23/2009 2) Insert New Row D_STAR (current - default) D_END (high date - default) INTO :ip,:ds,:de FROM TABLE ( = :ip AND( D_STAR >= CURRENT DATE AND D_END <= CURRENT DATE )) INSERT INTO TABLE SET ( = :ip = CURRENT DATE = ) Before 2/28/ /01/2009 1) Select Current Row Get keys, D_STAR & D_END After 2/28/ /01/2009 9/30/2009 UOW 10/1/2009 2) Insert New Row D_STAR (current - default) D_END (high date - default) 3) Close Current Row D_END Set D_END = New Row D_END -1 DAY 5

6 INTO :ip,:ds,:de FROM TABLE ( INSERT INTO TABLE SET ( = :ip = CURRENT DATE = ) = :ip AND( D_STAR >= CURRENT UPDATE TABLE AND D_END <= CURRENT SET DATE D_END = CURRENT DATE 1 DAY )) ( = :ip AND D_STAR = :ds AND D_END = :de ) Before 2/28/ /01/2009 1) Select Current Row Get keys, D_STAR & D_END After 2/28/ /01/2009 9/30/2009 2) Update Current Row D_END Set D_END = Current Date or Supplied Value INTO :ip,:ds,:de FROM TABLE ( = :ip AND( D_STAR >= CURRENT DATE AND D_END <= CURRENT DATE )) UPDATE TABLE SET D_END = CURRENT DATE ( = :ip AND D_STAR = :ds AND D_END = :de ) Time Series Rows 12/28/ /29/ /30/ /31/2008 1/1/2009 1/2/ Open ed Closed Interval 1 Date 1 Date Encapsulated Overlapping D_STAR_A D_END_A D_STAR_B D_END_B /28/ /31/ /29/ /30/ /28/ /31/ /31/ /01/ /31/ /31/ /28/ /31/ /31/ /31/ /31/ /01/ /31/ /01/ /01/ /01/ /01/ /01/ /01/ /01/ /31/ /01/2009 A.,A.D_STAR AS D_STAR_A,A.D_END AS D_END_A,B.D_STAR AS D_STAR_B,B.D_END AS D_END_B FROM SD00 A JOIN SD00 B ON ( A. = B. ) ( ( A.D_STAR = A.D_END AND A.D_STAR = B.D_STAR AND A.D_END <> B.D_END ) ) OR ( ( A.D_STAR = A.D_END AND A.D_END = B.D_END AND A.D_STAR <> B.D_STAR ) ) OR ( ( A.D_STAR <> B.D_STAR AND A.D_END <> B.D_END AND A.D_STAR <= B.D_STAR AND A.D_STAR <= B.D_END AND ( A.D_END >= B.D_STAR OR A.D_END >= B.D_END ) ) ) Join to Self Single Day Overlap Single Day Overlap Overlap / Encapsulated Application Insert Update Delete After SQL Trigger Before Trigger SQL INSERT DB2 Snapshot Before Trigger SQL 6

7 Application Managed Period Associate start & end user columns Allows DB2 to manage series Simplifies SQL Can eliminate overlaps System Enforced T_EFFC_STAR Timestamp or Date NOT NULL T_EFFC_END Timestamp or Date NOT NULL PERIOD BUSINESS_TIME(T_EFFC_STAR,T_EFFC_END) T_SYST_STAR Timestamp Generated Aways As Row Begin T_SYST_END Timestamp Generated Aways As Row T_SYST_CREA Timestamp Generated Aways As Transaction ID PERIOD SYSTEM_TIME(T_SYST_STAR,T_SYST_END) Rows DB2 Managed Series Open ed Business_Time (Application-inserts & values, DB2-series, overlaps?) Business Time effective start Business Time effective end, prev row adjusted on insert System_Time (DB2-inserts, values, series & no overlaps in ) System Time insert current TS System Time high TS, prev row adjusted on insert System Creator Time transaction created row TS DB2 Manages Series & Overlaps Business Business Open ed Application Manages Times & Inserts CREATE UNIQUE INDEX index ON table (,, BUSINESS_TIME WITHOUT OVERLAPS); Index 7

8 Choose One Predicates * FROM FOR BUSINESS_TIME AS OF :T-SYST FOR BUSINESS_TIME BETWEEN :T-SYST-STAR AND :T-SYST-END FOR BUSINESS_TIME FROM :T-SYST-STAR TO :T-SYST-END = :I-PRIC UPDATE active_table FOR PORTION OF BUSINESS_TIME FROM :T-SYST TO :T-SYST-END SET M_PRIC = :M-PRIC = :I-PRIC DELETE FROM active_table FOR PORTION OF BUSINESS_TIME FROM :T-SYST TO :T-SYST-END = :I-PRIC Application Insert Update Delete SQL DB2 Managed DB2 DB2 INSERT/ Update SQL DB2 Current SQL Yes One for One Names Types Size Precision Null Attrib etc. No Create Create Alter Add Versioning 8

9 Choose One SQL * FROM FOR SYSTEM_TIME AS OF :T-SYST FOR SYSTEM_TIME BETWEEN :T-SYST-STAR AND :T-SYST-END FOR SYSTEM_TIME FROM :T-SYST-STAR TO :T-SYST-END = :I-PRIC System & Business Support Database managed Integrated Automatically Referenced SQL extensions Time Zone Limitations Data Type Limitations SQL Limitations Database Function Limitations Dimension Limitations dimensions by user: 1) Time zone 2) Location 3) Daylight savings SQL WITH TIMEZONE option (DB2 10 provides) Offset from GMT by user Separate DB instance for each time zone Query perspective: source, query location or global SQL syntax & support of geo-temporal math TIME cross midnight, external mapping relation between date and time columns = complex date & time math, precision DATE can t be more granular TIMESTAMP precision (sec to picosec) Lacking Many Extensions Lacking User Defined Intervals (FYTD, QTD, etc.) Databases non-standard precision & ranges on types 9

10 Rigid time perspective(defaults to server location) query location global time perspective Lacks automated timezone offset compensation Lack user defined intervals Limited temporal predicates One time zone per DB2 instance Provides basic temporal event model Limited time dimensions Lack of ANSI temporal standards Limited built-in temporal functions and support GMT Offset Location Time Zone Daylight Savings Transaction Time (System) Validity Time (Business) Efficacy Time Publication Time Snapshot Generate Rows Validity Time (business) Transaction Time (system) Time Zone Fact (column) Daylight Savings GMT Offset Location 10

11 Lessons Learned Understand temporal design principles Avoid bad temporal designs Implement application temporal designs now Position to exploit upcoming DB2 features Be prepared to fulfill future temporal needs Robert Goodman 11