Document revision date: 15 July 2002

Figure 10-1 shows the tree structure of a sequential file.

Figure 10-1 Tree Structure for Sequential Files

The FILE HEADER structure is always the first structure displayed. From the FILE HEADER structure, the DOWN command moves the current position to the FILE ATTRIBUTES structure. The DOWN command from the FILE ATTRIBUTES structure moves the current position to the first record in the file. From the first record, the REST command will move the current position through the records in the file, displaying each one in turn. A series of NEXT commands will also accomplish this same operation.

Figure 10-2 shows the layout and contents of the records in a sequential file SEQ.DAT. Example 10-3 is an interactive examination of SEQ.DAT, showing the contents of three records in the file.

Figure 10-2 Record Layout and Content for SEQ.DAT

Example 10-3 Examining a Sequential File

$ ANALYZE/RMS_FILE/INTERACTIVE SEQ.DAT

FILE HEADER File Spec: DISK$DELPHIWORK:[RMS32]SEQ.DAT;3 File ID: (1170,2,2) Owner UIC: [730,465] Protection: System: RWED, Owner: RWED, Group: RWED, World: Creation Date: 7-MAY-1993 16:51:30.92 Revision Date: 8-MAY-1993 14:02:17.15, Number: 3 Expiration Date: none specified Backup Date: none posted Contiguity Options: none Performance Options: none Reliability Options: none

ANALYZE> DOWN

RMS FILE ATTRIBUTES File Organization: sequential Record Format: variable Record Attributes: carriage-return Maximum Record Size: 0 Longest Record: 73 Blocks Allocated: 3, Default Extend Size: 0 End-of-File VBN: 1, Offset: %X'00E4' File Monitoring: disabled Global Buffer Count: 0

ANALYZE> DOWN

DATA BYTES (VBN 1, offset %X'0000'): 7 6 5 4 3 2 1 0 01234567 ------------------------ -------- 31 30 30 30 30 30 00 49| 0000 |I.000001| 20 4C 41 54 49 47 49 44| 0008 |COMPAQ | 4E 45 4D 50 49 55 51 45| 0010 |COMPUTER| 52 4F 50 52 4F 43 20 54| 0018 |CORPORAT| 31 31 20 4E 4F 49 54 41| 0020 |ION 110 | 42 20 54 49 50 53 20 30| 0028 |SPIT BRO| 41 4F 52 20 4B 4F 4F 52| 0030 |OK ROAD | 41 55 48 53 41 4E 20 44| 0038 |NASHUA | 33 30 48 4E 20 20 20 20| 0040 | NH030| 00 31 36 30| 0048 |62. |

ANALYZE> NEXT

DATA BYTES (VBN 1, offset %X'004C'): 7 6 5 4 3 2 1 0 01234567 ------------------------ -------- 32 30 30 30 30 30 00 49| 0000 |I.000002| 49 46 46 4F 20 42 44 41| 0008 |ADB OFFI| 4C 50 50 55 53 20 45 43| 0010 |CE SUPPL| 20 20 20 20 20 53 45 49| 0018 |IES | 32 34 20 20 20 20 20 20| 0020 | 42| 4F 4D 45 53 4F 52 20 30| 0028 |0 ROSEMO| 45 52 54 53 20 54 4E 55| 0030 |UNT STRE| 49 44 20 4E 41 53 54 45| 0038 |ETSAN DI| 32 39 41 43 20 4F 47 45| 0040 |EGO CA92| 00 30 31 31| 0048 |110. |

ANALYZE> NEXT

DATA BYTES (VBN 1, offset %X'0098'): 7 6 5 4 3 2 1 0 01234567 ------------------------ -------- 33 30 30 30 30 30 00 49| 0000 |I.000003| 52 50 20 52 4F 4C 4F 43| 0008 |COLOR PR| 4C 20 47 4E 49 54 4E 49| 0010 |INTING L| 52 4F 54 41 52 4F 42 41| 0018 |ABORATOR| 34 39 20 20 20 53 45 49| 0020 |IES 94| 35 20 54 53 41 45 20 39| 0028 |9 EAST 5| 45 45 52 54 53 20 48 54| 0030 |TH STREE| 4F 59 20 57 45 4E 20 54| 0038 |T NEW YO| 30 31 59 4E 20 20 4B 52| 0040 |RK NY10| 00 33 30 30| 0048 |003. |

ANALYZE> EXIT

10.1.5 Examining a Relative File

Figure 10-3 Tree Structure of Relative Files

The tree structure of relative files also begins with the FILE HEADER and FILE ATTRIBUTES structures. From the FILE ATTRIBUTES structure, the next structure down is the PROLOG. The first structure down from the PROLOG is the FIRST DATA BUCKET. The data bucket structures can be examined with the REST command or one at a time with the NEXT command. The only information at the data bucket level is the number of the data bucket's virtual block.

The next structure down is the FIRST RECORD CELL IN FIRST BUCKET. You can examine the records in each cell by specifying either the REST command or a series of NEXT commands.

Example 10-4 shows an interactive examination of a relative file.

Example 10-4 Examining a Relative File

FILE HEADER File Spec: DISK$NEWWORK:[RMS32]REL.DAT;1 File ID: (9573,7,2) Owner UIC: [181,065] Protection: System: RWED, Owner: RWED, Group: RE, World: Creation Date: 22-MAY-1993 10:42:04.95 Revision Date: 22-MAY-1993 10:42:05.81, Number: 1 Expiration Date: none specified Backup Date: none posted Contiguity Options: contiguous-best-try Performance Options: none Reliability Options: none

ANALYZE> DOWN

RMS FILE ATTRIBUTES File Organization: relative Record Format: variable Record Attributes: carriage-return Maximum Record Size: 75 Blocks Allocated: 9, Default Extend Size: 0 Bucket Size: 3 File Monitoring: disabled Global Buffer Count: 0

ANALYZE> DOWN

FIXED PROLOG Prolog Flags: (0) PLG$V_NOEXTEND 0 First Data Bucket VBN: 2 Maximum Record Number: 2147483647 End-of-File VBN: 10 Prolog Version: 1

ANALYZE> DOWN

DATA BUCKET (VBN 2)

ANALYZE> DOWN

RECORD CELL (VBN 2, offset %X'0000'): Cell Control Flags: (2) DLC$V_DELETED 0 (3) DCL$V_REC 1 Record Bytes: 7 6 5 4 3 2 1 0 01234567 ------------------------ -------- 31 30 30 30 30 30 00 49| 0000 |I.000001| 20 4C 41 54 49 47 49 44| 0008 |COMPAQL | 4E 45 4D 50 49 55 51 45| 0010 |COMPUTER| 52 4F 50 52 4F 43 20 54| 0018 |CORPORAT| 31 31 20 4E 4F 49 54 41| 0020 |ION 110| 42 20 54 49 50 53 20 30| 0028 |SPIT BRO| 41 4F 52 20 4B 4F 4F 52| 0030 |OK ROAD | 41 55 48 53 41 4E 20 44| 0038 |NASHUA | 33 30 48 4E 20 20 20 20| 0040 | NH030| 31 36 30| 0048 | 62 |

If you use the REST command at the CELL AND RECORD level, the utility will display all the cells and records in the file, not just the cells and records in the current bucket.

10.1.6 Examining an Indexed File

The structure of an indexed file also begins with the FILE HEADER, FILE ATTRIBUTES, and PROLOG structures. From the PROLOG structure, the file structure branches to the area descriptors and the key descriptors. To branch to the area descriptor path, specify the command DOWN AREA. To branch to the key descriptor path, specify DOWN KEY.

The area descriptor path contains structures that show information about the various areas in the file. The key descriptor path contains the primary key structures (and data records) and any secondary key structures.

Figure 10-4 shows the structure following the area descriptor path.

Figure 10-4 Area Descriptor Path

Example 10-5 shows an examination of an area descriptor path from the PROLOG level.

Example 10-5 Examining an Area Descriptor Path

ANALYZE> DOWN AREA

AREA DESCRIPTOR #0 (VBN 3, offset %X'0000')) Bucket Size: 1) Alignment: AREA$C_NONE) Alignment Flags:) (0) AREA$V_HARD 0) (1) AREA$V_ONC 0) (5) AREA$V_CBT 0) (7) AREA$V_CTG 0) Current Extent Start: 1, Blocks: 9, Used: 7, Next: 8) Default Extend Quantity: 0)

Figure 10-5 shows the structure following the key descriptor path. As shown in the figure, you can branch directly to the DATA BUCKET, or you can branch to the INDEX ROOT BUCKET to begin examination of the index structure, eventually reaching the DATA BUCKET structure. Depending on whether you are examining the primary index structure or one of the alternate index structures, there is a difference in the contents of the record structure.

The PRIMARY RECORD structure contains the actual data records; the ALTERNATE RECORD structures contain secondary index data records (SIDRs).

Figure 10-5 Key Descriptor Path

Figure 10-6 displays the structure of the primary records.

Figure 10-6 Structure of Primary Records

Example 10-6 shows an examination of a primary record.

Example 10-6 Examining a Primary Record

PRIMARY DATA RECORD (VBN 4, offset %X'000E') Record Control Flags: (2) IRC$V_DELETED 0 (3) IRC$V_RRV 0 (4) IRC$V_NOPTRSZ 0 Record ID: 1 RRV ID: 1, 4-Byte Bucket Pointer: 4 Key: 7 6 5 4 3 2 1 0 01234567 ------------------------ -------- 31 30 30 30 30 30| 0000 |000001 |

ANALYZE> DOWN BYTES

7 6 5 4 3 2 1 0 01234567 ------------------------ -------- 31 30 30 30 30 30 00 49| 0000 |I.000001| 20 4C 41 54 49 47 49 44| 0008 |COMPAQ | 4E 45 4D 50 49 55 51 45| 0010 |COMPUTER| 52 4F 50 52 4F 43 20 54| 0018 |CORPORAT| 31 31 20 4E 4F 49 54 41| 0020 |ION 110 | 42 20 54 49 50 53 20 30| 0028 |SPIT BRO| 41 4F 52 20 4B 4F 4F 52| 0030 |OK ROAD | 41 55 48 53 41 4E 20 44| 0038 |NASHUA | 33 30 48 4E 20 20 20 20| 0040 | NH03| 31 36 30| 0048 |062 |

ANALYZE> UP

PRIMARY DATA RECORD (VBN 4, offset %X'000E') Record Control Flags: (2) IRC$V_DELETED 0 (3) IRC$V_RRV 0 (4) IRC$V_NOPTRSZ 0 Record ID: 1 RRV ID: 1, 4-Byte Bucket Pointer: 4 Key: 7 6 5 4 3 2 1 0 01234567 ------------------------ -------- 31 30 30 30 30 30| 0000 |000001 |

ANALYZE> DOWN RRV

BUCKET HEADER (VBN 4) Check Character: %X'00' Area Number: 0 VBN Sample: 4 Free Space Offset: %X'0104' Free Record ID Range: 4 - 255 Next Bucket VBN: 4 Level: 0 Bucket Header Flags: (0) BKT$V_LASTBKT 1 (1) BKT$V_ROOTBKT 0

Figure 10-7 displays the structure of the alternate records.

Figure 10-7 Structure of Alternate Records

Example 10-7 shows an examination of an alternate record.

Example 10-7 Examining an Alternate Record

ANALYZE> DOWN

SIDR RECORD (VBN 6, offset %X'000E') Control Flags: (4) IRC$V_NOPTRSZ 0 Record ID: 1 Key: 7 6 5 4 3 2 1 0 01234567 ------------------------ -------- 31 36 30 33 30| 0000 |03062 |

ANALYZE> DOWN

sidr pointer control flags: (2) IRC$V_DELETED 0 (5) IRC$V_KEYDELETE 0 sidr pointer record id: 1, 4-byte record VBN: 4

10.2 Generating an FDL File from a Data File

You can use the Analyze/RMS_File utility to create an FDL file generally called an analysis file. FDL files created by ANALYZE/RMS_FILE contain statistics about each area and key in the primary sections named ANALYSIS_OF_AREA and ANALYSIS_OF_KEY.

These analysis sections are then used by the Edit/FDL utility in its Optimize script. You can compare the statistics in these sections with your assumptions about the file's use; you may find some places in the file's structure where additional tuning will be possible.

To generate an FDL file from a data file, use the following command syntax:

ANALYZE/RMS_FILE/FDL filespec

With a command of this type, the FDL file obtains its file name from the input file specification; to assign a different file name, use the /OUTPUT qualifier. For example, the following command would generate an FDL file named INDEXDEF.FDL from the data file CUSTFILE.DAT:

$ ANALYZE/RMS_FILE/FDL/OUTPUT=INDEXDEF CUSTFILE.DAT

Example 10-8 shows an FDL file showing the KEY and ANALYSIS_OF_KEY sections for an indexed file with two keys.

Example 10-8 KEY and ANALYSIS_OF_KEY Sections in an FDL File

IDENT 2-JUN-1993 16:15:35 VMS ANALYZE/RMS_FILE Utility SYSTEM SOURCE VMS FILE ALLOCATION 9 BEST_TRY_CONTIGUOUS no BUCKET_SIZE 1 CONTIGUOUS no EXTENSION 0 GLOBAL_BUFFER_COUNT 0 NAME DISK$USERWORK:[WORK.RMS32]CUSTDATA.DAT;4 ORGANIZATION indexed OWNER [520,50] PROTECTION (system:RWED, owner:RWED, group:RWED, world:) READ_CHECK no WRITE_CHECK no RECORD BLOCK_SPAN yes CARRIAGE_CONTROL carriage_return FORMAT variable SIZE 0 AREA 0 BEST_TRY_CONTIGUOUS no BUCKET_SIZE 1 CONTIGUOUS no EXTENSION 0 KEY 0 CHANGES no DATA_AREA 0 DATA_FILL 100 DUPLICATES no INDEX_AREA 0 INDEX_FILL 100 LEVEL1_INDEX_AREA 0 NULL_KEY no PROLOG 1 SEG0_LENGTH 6 SEG0_POSITION 0 TYPE string KEY 1 CHANGES no DATA_AREA 0 DATA_FILL 100 DUPLICATES yes INDEX_AREA 0 INDEX_FILL 100 LEVEL1_INDEX_AREA 0 NULL_KEY no SEG0_LENGTH 5 SEG0_POSITION 68 TYPE string ANALYSIS_OF_AREA 0 RECLAIMED_SPACE 0 ANALYSIS_OF_KEY 0 DATA_FILL 50 DATA_RECORD_COUNT 3 DATA_SPACE_OCCUPIED 1 DEPTH 1 INDEX_FILL 4 INDEX_SPACE_OCCUPIED 1 MEAN_DATA_LENGTH 73 MEAN_INDEX_LENGTH 9 ANALYSIS_OF_KEY 1 DATA_FILL 14 DATA_RECORD_COUNT 3 DATA_SPACE_OCCUPIED 1 DEPTH 1 DUPLICATES_PER_SIDR 1 INDEX_FILL 4 INDEX_SPACE_OCCUPIED 1 MEAN_DATA_LENGTH 19 MEAN_INDEX_LENGTH 8

10.3 Optimizing and Redesigning File Characteristics

To maintain your files properly, you must occasionally tune them. Tuning involves adjusting and readjusting the characteristics of the file, generally to make the file run faster or more efficiently, and then reorganizing the file to reflect those changes.

There are two ways to tune files. You can redesign your FDL file to change file characteristics or parameters. You can change these characteristics either interactively with the Edit/FDL utility (the preferred method) or by using a text editor. With the redesigned FDL file, then, you can create a new data file.

You can also optimize your data file by using ANALYZE/RMS_FILE with the /FDL qualifier. This method, rather than actually redesigning your FDL file, produces an FDL file containing certain statistics about the file's use that you can then use to tune your existing data file.

Figure 10-8 shows how to use the RMS utilities to perform the tuning cycle.

Figure 10-8 RMS Tuning Cycle

Section 10.3.1 describes how to redesign an FDL file, and Section 10.3.2 explains how to optimize the run-time performance of a data file.

10.3.1 Redesigning an FDL File

There are many ways to redesign an FDL file. If you want to make small changes, you can use the ADD, DELETE, and MODIFY commands at the main menu (main editor) level.

Command	Function
ADD	Allows you to add one or more new lines to the FDL file. When you give the ADD command at the main menu level, the Edit/FDL utility prompts you with a menu displaying all legal primary attributes; your FDL file does not necessarily have to contain all these attributes. You can add a new primary attribute to your file, or you can add a new secondary attribute to an existing primary attribute. When you type in a primary attribute, the Edit/FDL utility displays all the legal secondary attributes for that primary attribute with their possible values. You can then select the secondary attribute that you want to add to your FDL file and supply the appropriate value for the secondary attribute.
DELETE	Allows you to delete one or more lines from the FDL file. When you give the DELETE command at the main menu level, the Edit/FDL utility prompts you with a menu displaying the current primary attributes of your FDL file. When you select the primary attribute for the attribute you want to remove from your FDL definition, the Edit/FDL utility displays the current values for all of the FDL file's secondary attributes. When you select the appropriate secondary from this list, the Edit/FDL utility removes it from the FDL definition. If you delete all of the secondary attributes of a primary attribute, the Edit/FDL utility removes the primary attribute from the current definition.
MODIFY	Allows you to change an existing line in the FDL definition. When you issue the MODIFY command at the main menu level, the Edit/FDL utility prompts you with a menu displaying the current primary attributes of your FDL file. When you type in a primary attribute, the Edit/FDL utility displays all the existing secondary attributes for that primary attribute with their current values. You can then select the secondary attribute of which you want to change the value and then supply the appropriate value for the secondary attribute.

However, if you want to make substantial changes to an FDL file, you should invoke the Touch-up script. Because sequential and relative files are simple in design, the Touch-up script works only with FDL files that describe indexed files. If you want to redesign sequential and relative files, you can use the command listed above (ADD, DELETE, or MODIFY), or you can go through the design phase again, using the scripts for those organizations.

To completely redesign an existing FDL file that describes an indexed sequential file, use the following command syntax:

EDIT/FDL/SCRIPT=TOUCHUP fdl-filespec

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