Storage Layout

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)
• Nums, Tokens and Doubles are arrays of values, and introduced with the number of entries (Num)

inf.basex

Contents: Meta information on a database and main memory indexes.

Description	Format	Method
1. Meta Data	Key/value pairs, suffixed by empty key (Token/Token): • PERM → User Permissions	DiskData() 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 Tag/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()
2.4. Document Index	Array of integers, representing the distances between all document pre values (Nums)	DocIndex()

(tbl|tbli).basex

Contents: Main database table and directory.

txt.basex

Contents: Heap file with text values (document names, string values of texts, comments and processing instructions).

atv.basex

Contents: Heap file with attribute values.

(txtl|txtr).basex

Contents: Value index for texts.

(atvl|atvr).basex

Contents: Value index for attributes.

(ftxa|ftxb|ftxc).basex

Contents: Trie full-text index.

(ftxx|ftxy|ftxz).basex

Contents: Fuzzy full-text index.