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Rebuilding IndexesGordon French of Fort Lauderdale recently asked, with reference to the INDEX.SUB program included on Utility Diskette Number 1, "How is it possible to force a rebuild of an index for a file?". The INDEX.SUB routine does not actually force a rebuild as it assumes that you will be rebuilding after adding a new index, in which case it will work perfectly. If however, it is suspected that the indexes have become corrupted it can be long-winded calling INDEX.SUB to remove, readd then rebuild the indexes. It is possible to instruct the system to rebuild the index for a field by mimicking the action taken by the system when it adds an index to a field. The system simply writes a record to the !INDEXING file, containing information about the file to update and the keyword %%ALL.IDS%%. The listing below shows a generic routine designed to allow the rebuilding of indexes from within an RBASIC program. To use, call with the file name and the field name/index name (EG USER, COMPANY_NAME.XREF, CUST*INV*AR). Note, network users should ensure they incorporate locking logic into this subroutine. 0001 SUBROUTINE REBUILD_INDEX(FILE,FIELD) 0002 * 0003 * Author AMcA 0004 * Date Jan 91 0005 * Purpose To rebuild an index for a field 0006 * COPYRIGHT Sprezzatura Ltd 1991. Permission given to 0007 * REVMEDIA subscribers to use in any form. 0008 0009 DECLARE SUBROUTINE FSMSG 0010 0011 OPEN "!INDEXING" TO IFILE THEN 0012 GOSUB GET_VOL_INFO 0013 GOSUB UPDATE_INDEX_FILE 0014 END ELSE 0015 FSMSG() 0016 END 0017 RETURN 0018 0019 GET_VOL_INFO: 0020 FILE_REC = XLATE("FILES",FILE,"","X") 0021 VOL_REC = XLATE("VOLUMES",FILE_REC<1>,"","X") 0022 VOL_INFO = FILE_REC<2>:"*":FILE_REC<3>:"*":VOL_REC<1> 0023 RETURN 0024 0025 UPDATE_INDEX_FILE: 0026 UPDATE_REC = VOL_INFO ; * Volume Information 0027 UPDATE_REC<2> = 1 ; * Number of transactions 0028 UPDATE_REC<3> = FIELD ; * Index to update 0029 UPDATE_REC<4> = "%%ALL.IDS%%" ; * Rebuild Flag 0030 UPDATE_REC := @FM : @FM : @FM 0031 READ ZERO_REC FROM IFILE, "0" ELSE ZERO_REC = @FM 0032 * Ensure there is a trailing field mark 0033 IF INDEX(ZERO_REC,@FM,1) ELSE ZERO_REC := @FM 0034 ZERO_REC := UPDATE_REC 0035 WRITE ZERO_REC TO IFILE, "0" 0036 CALL INDEX.FLUSH(VOL_INFO,'') 0037 RETURN (Volume 2, Issue 8, Page 7) |
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