Interrogation index file comparison
First Claim
1. A method of comparing in a data processing system a first file of data and a second file of data in only one pass through each of said first and second files, each of said first and second files comprising a set of records, each record including a key, comprising the steps of:
- initializing and loading a set of at least one data table including at least the step of loading a first key-index table with a first key-index record corresponding to each record in said first file in a first data pass, said first key-index record having a first interrogation index element related in a one to one correspondence to a first-file key of said first file;
sequentially fetching a second-file key from a record in said second file in a second data pass;
interrogating a corresponding record in said first key-index table having a second interrogation index element related to said second-file key and to said first interrogation index element; and
storing data representative of a matching relationship between said record of said first file and said record of said second file.
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Abstract
A method of comparing files takes three passes through data tables in memory to generate tables containing pointers to matches and mismatches by employing a method of keyword-index translation in which a keyword is taken from a first data table in a first pass and used as the index in loading an index table containing a pointer to the record containing that keyword. In a symmetric operation, a keyword is fetched from one table and used to interrogate the corresponding index table in a second pass. If there is a match, the record in the index table contains the pointer; and if there is a mismatch, the record contains a null. In an optional third pass, keywords are fetched from the other table and used to find records in the other table that are mismatches.
105 Citations
52 Claims
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1. A method of comparing in a data processing system a first file of data and a second file of data in only one pass through each of said first and second files, each of said first and second files comprising a set of records, each record including a key, comprising the steps of:
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initializing and loading a set of at least one data table including at least the step of loading a first key-index table with a first key-index record corresponding to each record in said first file in a first data pass, said first key-index record having a first interrogation index element related in a one to one correspondence to a first-file key of said first file; sequentially fetching a second-file key from a record in said second file in a second data pass;
interrogating a corresponding record in said first key-index table having a second interrogation index element related to said second-file key and to said first interrogation index element; andstoring data representative of a matching relationship between said record of said first file and said record of said second file. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method of comparing in a data processing system a first file of data and a second file of data, each of said first and second files comprising a set of records, each record including a key, comprising the steps of:
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in a first data pass initializing and loading a set of at least one data table including at least the step of loading a first key-index table with a first key-index record corresponding to each record in said first file, said first key-index record having a first interrogation index element related in a one to one correspondence to a first-file key of said first file; in a second data pass, sequentially fetching a second-file key from a record in said second file;
interrogating a corresponding record in said first key-index table having a second interrogation index element related in a one to one correspondence to said second-file key and to said first interrogation index element; andstoring data representative of a matching relationship between said record of said first file and said record of said second file; in a third data pass, initializing and loading a set of at least one data table including at least the step of loading a second key-index table with a second key-index record corresponding to each record in said second file, said second key-index record having an interrogation index related in a one to one correspondence to a second-file key of said second file; in a fourth data pass, sequentially fetching a first-file key from a record in said first file;
interrogating a corresponding record in said second key-index table having an interrogation index element related in a one to one correspondence to said first-file key; andstoring data representative of the relationship between said record of said first file and said record of said second file. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A method of comparing in a data processing system a first file of data and a second file of data, each of said first and second files comprising a set of records, each record including a key, comprising the steps of:
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in a first data pass, reading said first file from non-volatile storage and loading a set of at least one data table in memory including at least the step of loading a first key-index table with a first key-index record corresponding to each record in said first file, said first key-index record having a first interrogation index element related in a one to one correspondence to a first-file key of said first file; in a second data pass, reading said second file from non-volatile storage and loading a set of at least one data table in memory including at least the step of loading a second key-index table with a second key-index record corresponding to each record in said second file, said second key-index record having a second interrogation index element related in a one to one correspondence to a second-file key of said second file and to said first interrogation index element; in a third data pass, sequentially fetching from non-volatile storage a first-file key from a record in said first file; interrogating a corresponding record in said second key-index table having an interrogation index element related in a one to one correspondence to said first-file key; and storing data representative of a matching relationship between said record of said first file and said record of said second file; in a fourth data pass, sequentially fetching from non-volatile storage a second-file key from a record in said second file; interrogating a corresponding record in said first key-index table having an interrogation index element related in a one to one correspondence to said second-file key; and storing data representative of the relationship between said record of said first file and said record of said second file. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47)
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48. A method of comparing in a data processing system a first file of data and a second file of data located in non-volatile storage media, each of said first and second files comprising a set of records, each record including a key, comprising the steps of:
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initializing and loading a set of data tables in memory including first and second key-index tables, a match table for storing data representative of records in said first file having a counterpart record in said second file, a first mismatch table for storing data representative of records in said first file lacking a counterpart record in said second file and a second mismatch table for storing data representative of records in said second file lacking a counterpart record in said first file; sequentially fetching a second-file keyword from a record in said second file, interrogating a corresponding record in said first key-index table having an index element equal to said second-file keyword, and adding a record containing identifying data to said match table when said corresponding record has a non-null entry and adding a record containing identifying data to said second mismatch table when said corresponding record has a null entry; and sequentially fetching a first-file keyword from a record in said first file, interrogating a corresponding record in said second key-index table having an index element equal to said first-file keyword, and adding a record containing identifying data to said first mismatch table when said corresponding record has a null entry. - View Dependent Claims (49, 50, 51, 52)
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Specification