Difference between revisions of "Storage Layout"

From BaseX Documentation
Jump to navigation Jump to search
Line 21: Line 21:
 
| valign='top' | '''1. Meta Data'''
 
| valign='top' | '''1. Meta Data'''
 
| Key/value pairs, suffixed by empty key ({{Type|Token}}/{{Type|Token}}):<br />&bull; <code>PERM</code> → User Permissions
 
| Key/value pairs, suffixed by empty key ({{Type|Token}}/{{Type|Token}}):<br />&bull; <code>PERM</code> → User Permissions
| valign='top' | [https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/data/MetaData.java MetaData.read()]<br/>[https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/core/Users.java Users.read()]
+
| valign='top' | [https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/data/MetaData.java MetaData()]<br/>[https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/core/Users.java Users()]
 
|-
 
|-
 
| valign='top' | '''2. Main memory indexes'''
 
| valign='top' | '''2. Main memory indexes'''
Line 28: Line 28:
 
|-
 
|-
 
| valign='top' | '''2.1. Name Index'''<br/>Element/attribute names
 
| valign='top' | '''2.1. Name Index'''<br/>Element/attribute names
| 1. Token set, storing all names ({{Type|TokenSet}}:<br />2. One StatsKey instance per entry:<br/>2.1. Content kind (<code>Num</code>)<br />2.1. Number: min/max (<code>Doubles</code>)<br />2.2. Category: number of entries (<code>Num</code>), entries (<code>Tokens</code>)<br />2.3. Number of entries (<code>Num</code>)<br />2.4. Leaf flag (<code>Boolean</code>)<br />2.5. Maximum text length (<code>Double</code>; legacy, could be <code>Num</code>)
+
| 1. Token set, storing all names ({{Type|TokenSet}})<br />2. One StatsKey instance per entry:<br/>2.1. Content kind ({{Type|Num}})<br />2.1.1. Number: min/max ({{Type|Doubles}})<br />2.1.2. Category: number of entries ({{Type|Num}}), entries ({{Type|Tokens}})<br />2.2. Number of entries ({{Type|Num}})<br />2.3. Leaf flag ({{Type|Boolean}})<br />2.4. Maximum text length ({{Type|Double}}; legacy, could be {{Type|Num}})
 
| valign='top' | [https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/index/Names.java Names()]<br/>[https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/util/hash/TokenSet.java TokenSet.read()]<br/>[https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/index/StatsKey.java StatsKey()]
 
| valign='top' | [https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/index/Names.java Names()]<br/>[https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/util/hash/TokenSet.java TokenSet.read()]<br/>[https://github.com/BaseXdb/basex/blob/master/src/main/java/org/basex/index/StatsKey.java StatsKey()]
 
|-
 
|-

Revision as of 17:19, 26 October 2011

Version: 7.0

Data Types

  • Num: compressed integer (1-5 bytes)
  • Token: length (Num) and bytes of UTF8 byte representation
  • double: number, stored as token
  • boolean: boolean (1 byte, 00 or 01)
  • TokenSet: key array (Tokens), next/bucket/size arrays (Nums)

inf.basex

Description Format Method
Disk Data Database meta information DiskData()
1. Meta Data Key/value pairs, suffixed by empty key (Token/Token):
PERM → User Permissions
MetaData()
Users()
2. Main memory indexes Key/value pairs, suffixed by empty key (Token/Token):
TAGS → Tag Index
ATTS → Attribute Index
PATH → Path Index
NS → Namespaces
DOCS → Document Index
DiskData()
2.1. Name Index
Element/attribute names
1. Token set, storing all names (TokenSet)
2. One StatsKey instance per entry:
2.1. Content kind (Num)
2.1.1. Number: min/max (Doubles)
2.1.2. Category: number of entries (Num), entries (Tokens)
2.2. Number of entries (Num)
2.3. Leaf flag (Boolean)
2.4. Maximum text length (Double; legacy, could be Num)
Names()
TokenSet.read()
StatsKey()
2.2. Path Index 1. Flag for path definition (Boolean, always true; legacy)
2. PathNode:
2.1. Name reference (Num)
2.2. Node kind (Num)
2.3. Number of occurrences (Num)
2.4. Number of children (Num)
2.5. Double; legacy, can be reused or discarded
2.6. Recursive generation of child nodes (→ 2)
PathSummary()
PathNode()
2.3. Namespaces 1. Token set, storing prefixes (TokenSet)
2. Token set, storing URIs (TokenSet)
3. NSNode:
3.1. pre value (Num)
3.2. References to prefix/URI pairs (Nums)
3.3. Number of children (Num)
3.4. Recursive generation of child nodes (→ 3)
Namespaces()
NSNode()