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Example 1. Non-Dense (Primary) Index, “ONE FREE” matches file ordering. Records. Index. 111 121 1112 111 131 2143 121 234 4544 121 349 6341 … 235 121 2311 235 122 4993 … 266 333 4343 …. 111 121 1113 235 121 2311 266 333 4343. block. block. Search for 235 122 4993. block. - PowerPoint PPT Presentation
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INLS 623 Indexing examples BMH/SWH
Example 1. Non-Dense (Primary) Index, “ONE FREE” matches file ordering
Index
111 121 1113235 121 2311266 333 4343
Records
111 121 1112111 131 2143121 234 4544121 349 6341 …
235 121 2311235 122 4993 …
266 333 4343 …
block
block
blockSearch for235 122 4993
INLS 623 Indexing examples BMH/SWH
Example 2. (Clustered) Non-Dense Index (ONE FREE—matches file ordering)
Index Records
BlueGreenGreyRedYellow
Blue 2Blue 3Blue 9Green 1Green 2
Green 6Grey 1Red 1
Red 9Red 10Yellow6
block
block
block
INLS 623 Indexing examples BMH/SWH
Example 3. Secondary (Dense) Index1 entry per record
Index Records
BlueBlueBlueGreenGreenGreenYellowYellowYellow
12 Blue14 Yellow15 Green17 Yellow19 Blue23 Yellow29 Green33 Green43 Blue
INLS 623 Indexing examples BMH/SWH
Example 4. Secondary (Dense) Index1 entry per value, all addresses
Index Records
Blue
Green
Yellow
12 Blue14 Yellow15 Green17 Yellow19 Blue23 Yellow29 Green33 Green43 Blue
INLS 623 Indexing examples BMH/SWH
Example 5. Secondary (Dense) Index1 entry per value, address to addresses
Index Records
Blue
Green
Yellow
12 Blue14 Yellow15 Green17 Yellow19 Blue23 Yellow29 Green33 Green43 Blue
Addresses
INLS 623 Indexing examples BMH/SWH
Example 6. Multilevel IndexFirst Level Second Level Records
13415232425…3942…5253…
1
15
25
39
52
1
25
52
INLS 623 Indexing examples BMH/SWH
Example 7a. B+ Tree Node Structure
p1 v1 p2 v2 p3 v3 p4 v4 p5
Node 1 Node 2 Node 3 Node 4 Node 5
INLS 623 Indexing examples BMH/SWH
Example 7b. B+ Tree Node Structure
p1 15 p2 30 p3 50 p4 93 p5
1 12 15
16 21 24 30
31 33 47 50
51 56 78 81 93
94 99 103 …
INLS 623 Indexing examples BMH/SWH
HashingFunction(value) = location (i.e. bin)
Example: Mod 13 of (SSN) =• 123-45-6789 mod 13 = 1• 234-56-7899 mod 13 = 7• 864-93-5196 mod 13 = 8• 963-77-5936 mod 13 = 6• 058-32-9744 mod 13 = 5• 532-87-1523 mod 13 = 2• 274-98-6648 mod 13 = 1
INLS 623 Indexing examples BMH/SWH
• Bin 1 – 123-45-6789 mod 13 = 1– 274-98-6648 mod 13 = 1
• Bin 2– 532-87-1523 mod 13 = 2
• Bin 3• Bin 4• Bin 5
– 058-32-9744 mod 13 = 5• Bin 6
– 963-77-5936 mod 13 = 6• Bin 7
– 234-56-7899 mod 13 = 7• Bin 8
– 864-93-5196 mod 13 = 8• …. (plus overflow Bin)
Indexing Organization Options
INLS 623 Indexing examples BMH/SWH
File (on Disk) Index in RAM
Unordered
Ordered No Index
Ordered One Free Primary Non-Dense Index (B+Tree)
and possibly
Multiple (costly) Secondary Dense Indexes (B+Tree)
Hash No physical index
