CA IDMS TM /DB Indexing Part 1

Transcription

1 International Toll Free Audio Numbers International Toll Free Audio Numbers Participant Dial-In Number(s): US Dial-In #: Int'l/Canada Dial-In #: Conference Audio Conference ID Alternate 800 service by country CA IDMS TM /DB Indexing Part 1 Internals Bill Abbott Dick Weiland February 14, 2008 Legal This presentation was based on current information and resource allocations as of February 14, 2008 and is subject to change or withdrawal by CA at any time without notice. Notwithstanding anything in this presentation to the contrary, this presentation shall not serve to (i) affect the rights and/or obligations of CA or its licensees under any existing or future written license agreement or services agreement relating to any CA software product; or (ii) amend any product documentation or specifications for any CA software product. The development, release and timing of any features or functionality described in this presentation remain at CA s sole discretion. Notwithstanding anything in this presentation to the contrary, upon the general availability of any future CA product release referenced in this presentation, CA will make such release available (i) for sale to new licensees of such product; and (ii) to existing licensees of such product on a when and if-available basis as part of CA maintenance and support, and in the form of a regularly scheduled major product release. Such releases may be made available to current licensees of such product who are current subscribers to CA maintenance and support on a when and if-available basis. In the event of a conflict between the terms of this paragraph and any other information contained in this presentation, the terms of this paragraph shall govern. 3 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 1 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

2 Poll: Please Identify Your Job Function > [Live Meeting Multiple Choice Poll. Use Live Meeting > Edit Slide Properties... to edit.] > Database Administrator > Application Developer >IT Manager >Consultant >Vendor >Other Abstract This session is an overview of the components of an CA IDMS index and how they are used. Topics covered are the processes of splitting, spawning, orphan handling, space usage, and internal usage of index structures. 5 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Topics of Discussion > Index Structure >Record Insertion > Index Navigation 6 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 2 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

3 Index Structure > An integrated index is a pointer array managed by the DBMS and composed of internal record types transparent to the application > All set orders supported by chain sets are available through indexes along with additional capabilities Unsorted (FIRST, LAST, NEXT, PRIOR) Sorted By dbkey By symbolic key Duplicates FIRST/LAST/DBKEY 7 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Index Structure (cont.) > All indexes are composed of the following components Index owners SR7 (system-owned indexes) User records (user-owned indexes) Index structure SR8 Member records 8 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals SR7 > SR7 records are stored as calc records using the index name as the calckey > User records are stored based on the location mode assigned to them within their schema *********************************************************** * * * SR7 ( OF SYSTEM- INDEX) * * * *********************************************************** OFFSET SR7 DSECT SR7RID EQU 7 RECORD ID OF SR7 S SR7CALCN DS F -10 NEXT IN CALC SET SR7CALCP DS F -C PRIOR IN CALC SET SR7DBKN DS F -8 NEXT IN SR7 SR C SR7DBKP DS F -4 PRIOR IN SR7 SR SR7PFXLN EQU *-SR7 PREFIX LENGTH SR7SET DS CL16 +0 SET NAME (CALC KEY) SR7DSLEN EQU *-SR7 LENGTH OF DSECT 9 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 3 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

4 SR8 > The major component of an index is the SR8 record which is basically an array of dbkeys and, optionally, symbolic keys > Each SR8 has a fixed portion > Each SR8 also contains a variable portion whose format is dependent on the characteristics of the index IBC Index Order 10 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals SR8 Fixed Portion ******************************************************************* SR8 (B-TREE NODE) * * ******************************************************************* OFFSET SR8 DSECT SR8RID EQU 8 RECORD ID OF SR8 S SR8NDBK DS -C NEXT IN SR SR8PDBK DS -8 PRIOR IN SR SR8ODBK DS F -4 INDEX,SR7 OR USER 0000C SR8PFXLN EQU *-SR8 LENGTH OF PREFIX 00000C SR8UPDBK DS F +0 APPROX DBKEY OF UPLEVEL * (-1 if TOP LEVEL) SR8ORPH DS F NUMBER of ORPHANED ENTRIES SR8NUME DS CURRENT NUMBER OF ENTRIES SR8CUSH DS CUSHSION SIZE, BYTES SR8ELEN DS LENGTH OF ONE INDEX ENTRY 00001A SR8TKL DS H TOTAL KEY LENGTH -1 SR8SORT #FLAG X 80 SORTED INDEX SR8SYMB #FLAG X 40 SORTED ON SYMBOLIC KEY SR8COMP #FLAG X 20 COMPRESSED KEYS SR8DSC #FLAG X 10 DESCENDING SEQUENCE SR8DDBK #FLAG X 08 DUPLICATES ORDERED BY DBKEY 00001C SR8FLAGS DS XL1 FLAG BYTE 00001D SR8LEVL DS XL1 LEVEL NUMBER SR8BOTM EQU 0 ZERO IS BOTTOM LEVEL 00001E DS H RESERVED SR8VAR DS 0F START of VARIABLE PORTION SR8DSLEN EQU *-SR8 FIXED LENGTH INCLUDING * PREFIX 11 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals SR8 Variable Portion *FOR UNSORTED INDEX SETS, THE VARIABLE PORTION CONSISTS OF 0 THRU SR8NUME MEMBER DATABASE KEYS * OFFSET SR8UNSRT DSECT SR8VAR FOR UNSORTED SETS SR8UNDBK DS F DBKEY OF MEMBER RECORD SR8UNLEN EQU *-SR8UNSRT LENGTH OF ENTRY (SR8ELEN) *IF THE INDEX IS SORTED ON MEMBER DBKEY, THE TOP AND * INTERMEDIATE LEVEL SR8 NODE POINTERS ARE PAIRED WITH * THE MEMBER DBKEYS. THE BOTTOM-LEVEL SR8S CONTAIN * ONLY MEMBER DBKEYS. * SR8SDBK DSECT TOP/INTERMEDIATE LEVEL NODE SR8SDNOD DS F DBKEY OF NEXT LOWER NODE SR8SMEM DS F DBKEY OF MEMBER RECORD SR8SDLEN EQU *-SR8DBK LENGTH OF ENTRY (SR8ELEN) 12 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 4 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

5 SR8 Variable Portion (cont.) *IF THE INDEX SET IS SORTED ON SYMBOLIC KEY, EACH ENTRY IN TOP AND INTERMEDIATE LEVEL SR8S CONTAINS A NODE POINTER PAIRED WITH THE OFFSET IN THE SR8 OF THE SYMBOLIC KEY. FOR BOTTOM LEVEL SR8S, THE MEMBER * DBKEY REPLACES THE NODE POINTER. OFFSET SR8SKEY DSECT ENTRY FOR SORTED ON SYMBOLIC * KEY SR8SKNOD DS 0XL4 DBKEY OF LOWER NODE (TOP/INT * LEVEL) SR8SKMEM DS XL4 DBKEY OF MEMBER(BOTTOM LEVEL) SR8SKKOF DS H OFFSET TO SYMBOLIC KEY SR8SKLEN EQU *-SR8SKEY LENGTH OF ENTRY (SR8ELEN) *FOR SYMBOLIC KEYED INDEXES WITH DUPLICATES ORDERED BY DBKEY, TOP AND INTERMEDIATE LEVELS ALSO CONTAIN THE DBKEYOF THE CORRESPONDING MEMBER, WHICH LOGICALLY REPRESENTS THE LO-ORDER PORTION OF THE SYMBOLIC * KEY SR8SKMKY XL4 DBKEY OF MEMBER (TOP/INT * LEVELS) 0000A SR8SKDLN EQU *-SR8SKEY SR8ELEN IF DUPS BY DBKEY * *EACH SYMBOLIC KEY IS OF THE FOLLOWING FORMAT * SR8SYMBK DSECT SYMBOLIC KEY ENTRY SR8SYCOM DS XL1 KEY PREFIX COMMON TO PRIOR * KEY SR8SYLEN DS XL1 LENGTH-1 OF FOLLOWING KEY SR8SYKEY DS 0XL256 ACTUAL KEY, 1->256BYTES SR8SYMLN EQU *-SR8SYMBK LENGTH WITHOUT SYMBOLIC KEY 13 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals SR8 Record Types > Level-0 (low-level) Dbkey/symbolic key values represent actual user record occurrences Stored based on the index s displacement clause Space allocated per SR8 is only enough to contain the number of active entries and the cushion >Intermediate Dbkey/symbolic key values represent lower level SR8 occurrences Stored VIA the set owner Space allocated per SR8 is enough to contain the number of entries specified by the IBC clause plus the cushion 14 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Member Records > Each member record occurrence contains an optional INDEX (UP) pointer to a level-0 SR8 record in the index > If the indexed set has a user-defined owner, the member occurrence can include an pointer that points directly to the owner occurrence 15 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 5 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

6 Sample Index Structure SR8 DB-KEY POINTERS ACCESS VIA SR8 PREFIX SR8 B SR8 C NESLON STUART SR8 D SR8 E SR8 F SR8 G SR8 H SR8 I ADAMS 1 ADAMS 1 DAVIS EAST GREY HALL JONES LONG NESLON STUART UPTON ADAMS DAVIS GREY JONES NELSON STUART UPTON ADAMS EAST HALL LONG 16 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Record Insertion > Records are added into an index by inserting a new entry into a level-0 SR8 record > When an SR8 record exceeds the maximum number of entries as defined by the index s IBC count or there is no more room to expand an SR8, a SPLIT occurs > The top level of a sorted index can contain only one SR8 record > When the top level SR8 record is full, the DBMS must split the SR8 and SPAWNS a new top level. > The new top level points to the two lower level SR8 records created by the split 17 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Record Insertion (cont.) > When a record is to be added into an SR8 and the new key s position would be at the beginning or the end of an SR8, the only record entry placed into the new SR8 record is for the member record being inserted IBC=3 Add record 18 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 6 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

7 Record Insertion (cont.) SPLIT SPAWN LEVEL 1 SR8 C SR8 B LEVEL 0 SR8 B 19 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Record Insertion (cont.) > When a record is to be inserted into the middle of an SR8 record and the SR8 is already at the maximum number of entries, the new entry is inserted by using the SR8 record s cushion. The SR8 is then split and half of the SR8 record s entries are moved to the new SR8 occurrence. 20 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Record Insertion (cont.) IBC=3 SR8 B Add record SPLIT 21 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 7 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

8 Record Insertion (cont.) SPAWN LEVEL 1 SR8 C SR8 B LEVEL 0 22 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Orphans > Orphans are created when an SR8 record in a LINKED index splits and member record entries are moved from the original SR8 occurrence to the new SR8 record The index pointers in the records whose entries were relocated remains pointing at the original SR8 The orphan count in the original SR8 is incremented by the number of entries that were relocated Orphans may be adopted when the index is subsequently navigated in an update mode 23 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Orphan Example IBC=3 0 Add record 24 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 8 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

9 Orphan Example (cont.) IBC=3 SR8 C 0 SPAWN LEVEL 1 1 SR8 B 0 LEVEL 0 25 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Index Navigation Index currencies are maintained within the set s variable OR52 control block (VOR) > The VOR is located by adding the displacement found at location x 04 of the set s OR52 to the VARSS base address found at location x 38 of the VB50 (VIB) > The dbkeys of the index s owner, prior, current, and next SR8 records are found in fields VORODBK, VORPDBK, VORCDBK, and VORNDBK respectively > The dbkeys of the prior, current, and next member records for the index are found in fields VORIXPRI, VORIXCUR, and VORIXNXT respectively 26 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Index Navigation (cont.) * VOR: VARIABLE OR52 SUBSCHEMA TABLE ELEMENT DSECT OFFSET VOR DSECT VORODBK DS DBKEY OF SET VORPDBK DS PRIOR DBKEY OF SET VORCDBK DS CURRENT DBKEY OF SET 00000C VORNDBK DS F NEXT DBKEY OF SET VORCDEF DS CURRENT OR/MR DEF OF SET VORMRD1 DS LAST MR53 REFERENCED OF SET VORMRD2 DS A 2ND LAST MR53 REF. OF SET 00001C VORMID1 DS LAST MEMBER RECID REFERENCED 00001E VORMID2 DS H 2ND LAST MEMBER RECID REF VORVIBN DS A NEXT OF VIB OR REF LIST VORFLAG1 DS XL1 GENERAL FLAG BYTE VORVKEY EQU X 80 SYMBOLIC KEY IS VALID VORUNUS1 DS XL1 RESERVED VORIXICS DS XL1 INDEX INTEGRITY CHECK SWITCH VORTICK DS XL1 DELETE RETURN INDICATOR VORIXPRI DS PRIOR OF INDEX 00002C VORIXCUR DS CURRENT OF INDEX VORIXNXT DS F NEXT OF INDEX VORIXPOF DS OFFSET OF PRIOR IN SR VORIXCOF DS OFFSET OF CURRENT IN SR VORIXNOF DS OFFSET OF NEXT IN SR A VORIPOFF DS H PRE-FIXED INSERT OFFSET 00003C VORIPDBK DS PRE-FIXED INSERT SR8 DBKEY VORSPDBK DS F CHAIN SET PRIOR DBK MODLINK VORCSBN DS NEXT OF VOR CSB CURRENCY VORCLKGA DS A ADDR OF LKG FOR CURRENT OF SET 00004C VOREND DS 0F END OF DSECT 00004C VORDSLEN EQU *-VOR LENGTH OF DSECT 27 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 9 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

10 Index Navigation (cont.) > FIND/OBTAIN/RETURN verbs that supply a symbolic key will search the index from top to bottom using a binary search > All the other retrieval commands will use set currencies or member index pointers to initiate searches at a level-0 SR8 record and will search for a specific dbkey 28 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Index Navigation (cont.) SR8 DB-KEY POINTERS ACCESS VIA SR8 PREFIX SR8 B SR8 C NESLON STUART SR8 D SR8 E SR8 F SR8 G SR8 H SR8 I ADAMS 1 ADAMS 1 DAVIS EAST GREY HALL JONES LONG NESLON STUART UPTON ADAMS DAVIS GREY JONES NELSON STUART UPTON ADAMS EAST HALL LONG 29 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Session Summary > Index Structure >Record Insertion > Index Navigation 30 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 10 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

11 Poll: How Useful Was This Presentation > [Live Meeting Multiple Choice Poll. Use Live Meeting > Edit Slide Properties... to edit.] >Extremely Useful > Very Useful >Mildly Useful > Of no Value For More Information > CA IDMS /DB Indexing, Part 2 of 2: Maintaining Indexes webcast February 21, AM ET Register at ca.com/events > ca.com/support CA IDMS home page CA IDMS recorded webcasts, roadmap, tech documents, > ca.com/idms > ca.com/caworld 32 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals Legal Certain information in this presentation may outline CA s general product direction. All information in this presentation is for your informational purposes only and may not be incorporated into any contract. CA assumes no responsibility for the accuracy or completeness of the information. To the extent permitted by applicable law, CA provides this document as is without warranty of any kind, including without limitation, any implied warranties or merchantability, fitness for a particular purpose, or non-infringement. In no event will CA be liable for any loss or damage, direct or indirect, from the use of this document, including, without limitation, lost profits, lost investment, business interruption, goodwill, or lost data, even if CA is expressly advised of the possibility of such damages. 33 February 2008 CA IDMS/DB Indexing, Part 1 of 2; Internals 11 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA

12 Q and A Register for Part 2, February 21, 2008 at ca.com/events CA IDMS Index Internals 12 February 2008 CA IDMS/DB Indexing Part 1 of 2; Internals Copyright 2008 CA