Changes

The following This article is part of the [[Advanced User's Guide]]. It presents some low-level details on how data types are used for specifying is stored in the storage layout:database files.

! Example(native → hex integers)|-| {{Type|Num}}| Compressed integer (1-5 bytes), specified in [https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/util/Num.java Num.java]| {{Code|15}} → {{Code|0F}}; {{Code|511}} → {{Code|41 FF}}<br/>|-| {{Type|Token}}| Length ({{Type|Num}}) and bytes of UTF8 byte representation| {{Code|Hello}} → {{Code|05 48 65 6c 6c 6f}}|-| {{Type|Double}}| Number, stored as token| {{Code|123}} → {{Code|03 31 32 33}}|-| {{Type|Boolean}}| Boolean (1 byte, {{Code|00}} or {{Code|01}})| {{Code|true}} → {{Code|01}}

| valign='top' {{Type|Nums}}, {{Type| Tokens}}, {{Type|NumDoubles}}| valign='top' Arrays of values, introduced with the number of entries| {{Code| Compressed integer (1,2}} → {{Code|02 01 31 01 32}}|-5 bytes| {{Type|TokenSet}}| Key array ({{Type|Tokens}}), next/bucket/size arrays (3x {{Type|Nums}})| valign='top' | 15 → 0x0F

The following tables present illustrate the layout of the BaseX database files. All files are suffixed with <code>{{Code|.basex</code>}}.

==Meta Data, Name/Path/Doc Indexes: <code>{{Code|inf</code>}}==

| valign='top' | '''1. Meta Data'''| valign='top' | 1. Key/value pairs , in no particular order ({{Type|Token}}/{{Type|Token}}):<br />&nbsp; &bull; Examples: {{Code|FNAME}}, {{Code|TIME}}, {{Code|SIZE}}, ...<codebr />&nbsp; &bull; {{Code|PERM</code> }} → Number of users ({{Type|Num}}), and name/password/permission values for each user ({{Type|Token}}/{{Type|Token}}/{{Type|Num}})<br/>2. Empty key as finalizer| valign='top' | [https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/data/DiskData.java DiskData()]<br/>[https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/data/MetaData.java MetaData()]<br/>[https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/core/Users.java Users()]

| valign='top' | '''2. Main memory indexes'''| 1. Key/value pairs , in no particular order ({{Type|Token}}/{{Type|Token}}):<br />&nbsp; &bull; <code>{{Code|TAGS</code> }} → Tag Element Name Index<br />&nbsp; &bull; <code>{{Code|ATTS</code> }} → Attribute Name Index<br />&nbsp; &bull; <code>{{Code|PATH</code> }} → Path Index<br />&nbsp; &bull; <code>{{Code|NS</code> }} → Namespaces<br />&nbsp; &bull; <code>{{Code|DOCS</code> }} → Document Index<br/>2. Empty key as finalizer| valign='top' | [https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/data/DiskData.java DiskData()]

| valign='top' | '''2 a) Name Index'''<br/>TagElement/attribute names

| valign='top' | [https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/index/Names.java Names()]<br/>[https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/util/hash/TokenSet.java TokenSet.read()]<br/>[https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/index/StatsKey.java StatsKey()]

| valign='top' | '''2 b) Path Index'''| 1. Flag for path definition ({{Type|Boolean}}, always <code>{{Code|true</code>}}; legacy)<br/>2. PathNode:<br/>2.1. Name reference ({{Type|Num}})<br/>2.2. Node kind ({{Type|Num}})<br/>2.3. Number of occurrences ({{Type|Num}})<br/>2.4. Number of children ({{Type|Num}})<br/>2.5. {{Type|Double}}; legacy, can be reused or discarded<br/>2.6. Recursive generation of child nodes (→ 2)| valign='top' | [https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/index/path/PathSummary.java PathSummary()]<br/>[https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/index/path/PathNode.java PathNode()]

| valign='top' | '''2 c) Namespaces'''

| valign='top' | [https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/data/Namespaces.java Namespaces()]<br/>[https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/data/NSNode.java NSNode()]

| valign='top' | '''2 d) Document Index'''

| valign='top' | [https://github.com/BaseXdb/basex/blob/master/basex-core/src/main/java/org/basex/index/DocIndex.java DocIndex()]

==Node Table: <code>{{Code|tbl</code>}}, <code>{{Code|tbli</code>}}==

* <code>{{Code|tbl</code>}}: Main database table, stored in blocks.* <code>{{Code|tbli</code>}}: Database directory, organizing the database blocks.

* <code>==Texts: {{Code|txt</code>: Heap file for text values (document names, string values of texts}}, comments and processing instructions)* <code>{{Code|atv</code>: Heap file for attribute values.}}==

* {{Code|txt}}: Heap file for text values (document names, string values of texts, comments and processing instructions)* {{Code|atv}}: Heap file for attribute values. ==Value Indexes: <code>{{Code|txtl</code>}}, <code>{{Code|txtr</code>}}, <code>{{Code|atvl</code>}}, <code>{{Code|atvr</code>}}==

* <code>{{Code|txtl</code>}}: Heap file with ID lists.* <code>{{Code|txtr</code>}}: Index file with references to ID lists.The '''Attribute Index''' is contained in the files <code>{{Code|atvl</code> }} and <code>{{Code|atvr</code>; it uses }}, the '''Token Index''' in {{Code|tokl}} and {{Code|tokr}}. All have the same layout. ==Full-Text Fuzzy Index: <code>ftxx</code>, <code>ftxy</code>, <code>ftxz</code>==

...will soon be reimplementedFor a more detailed discussion and examples of these file formats please see [[Index File Structure]].

==Full-Text Trie Fuzzy Index: <code>ftxa</code>{{Code|ftxx}}, <code>ftxb</code>{{Code|ftxy}}, <code>ftxc</code>{{Code|ftxz}}==

...will may soon be dismissedreimplemented.