CapraISIS

Modern CDS/ISIS Implementation Using SQLite FTS5

CapraISIS brings UNESCO's revolutionary CDS/ISIS text database principles to modern Python. CDS/ISIS (Computerised Documentation System / Integrated Set of Information Systems, 1985–2005) pioneered inverted file indexing for bibliographic records. CapraISIS implements the same algorithms using SQLite FTS5 as the storage backend.

Why CDS/ISIS Principles Still Matter

The CDS/ISIS architecture solved a fundamental problem: O(log k) retrieval from millions of text records. Modern systems like Elasticsearch, Lucene, and SQLite FTS5 all implement variations of the same inverted file index that CDS/ISIS pioneered.

CapraISIS is:

• Portable: Single SQLite file, no server required
• Fast: Sub-100ms queries on 70M+ records
• Simple: Pure Python, no dependencies beyond stdlib
• Proven: Based on 40 years of CDS/ISIS architecture

Installation

pip install capraisis

Or install from source:

git clone https://github.com/capraCoder/capraisis
cd capraisis
pip install -e .

Quick Start

Python API

from capraisis import CapraIndex

# Create or open an index
index = CapraIndex("my_corpus.db")

# Add records
index.add(
    id="10.5281/zenodo.12345",
    title="Quantum Mechanics and Consciousness",
    content="A paper exploring the relationship between...",
    year=2024,
    prefix="10.5281"
)

# Bulk add
records = [
    ("10.1234/a", "Title A", "Content A", 2023, "10.1234"),
    ("10.1234/b", "Title B", "Content B", 2024, "10.1234"),
]
index.bulk_add(records)

# Search
results = index.search("quantum consciousness")
for r in results:
    print(f"{r['year']} | {r['id']} | {r['title']}")

# Boolean queries (FTS5 syntax)
results = index.search("quantum AND NOT classical")
results = index.search('"exact phrase"')
results = index.search("title:quantum")  # Field-specific

# Statistics
stats = index.stats()
print(f"Total records: {stats['total_records']:,}")

Command Line

# Build index from JSONL files
python -m capraisis build "data/*.jsonl" --output corpus.db

# Search
python -m capraisis search corpus.db "quantum mechanics"
python -m capraisis search corpus.db "neural network" --year 2024

# Show statistics
python -m capraisis stats corpus.db

# Benchmark
python -m capraisis benchmark corpus.db

Building Large Indices (e.g., DataCite)

For large datasets (millions of records), use the IndexBuilder:

from capraisis import IndexBuilder

builder = IndexBuilder(
    "datacite.db",
    batch_size=100_000,      # Commit every 100K records
    progress_interval=1_000_000  # Report every 1M records
)

# Build from DataCite JSONL files
stats = builder.add_jsonl_files(
    "/path/to/DataCite/**/*.jsonl",  # Adjust to your extraction path
    resume=True  # Skip already processed files
)

print(f"Indexed {stats['total_records']:,} records in {stats['elapsed_hours']:.2f} hours")

Obtaining DataCite Data

The DataCite Public Data File contains metadata for 70M+ DOIs. Download options:

Source	URL
Official Repository	https://datafiles.datacite.org/
Internet Archive	Search for "DataCite Public Data File"
DataCite API	https://support.datacite.org/docs/api

Documentation: https://support.datacite.org/docs/datacite-public-data-file

File Format:

• Large .tar file containing compressed NDJSON (newline-delimited JSON)
• Each line = one bibliographic record with DOI, title, description, year, etc.
• Uncompressed size: ~350 GB

Processing:

# Extract the tar file
tar -xf DataCite_Public_Data_File_2024.tar -C /path/to/extraction/

# Then build with CapraISIS
python -m capraisis build "/path/to/extraction/**/*.jsonl" --output datacite.db

Usage: Subject to DataCite Data File Use Policy.

Custom Record Extractors

Define your own extractor for non-DataCite formats:

from capraisis import IndexBuilder

def my_extractor(rec: dict):
    """Extract fields from your JSON format."""
    return (
        rec.get('identifier'),      # id
        rec.get('name'),            # title
        rec.get('abstract', ''),    # content
        str(rec.get('year', '')),   # year
        rec.get('source', '')       # prefix
    )

builder = IndexBuilder("my_index.db")
builder.add_jsonl_files("my_data/*.jsonl", extractor=my_extractor)

FTS5 Query Syntax

CapraISIS supports the full SQLite FTS5 query syntax:

Query	Meaning
quantum mechanics	Both terms (implicit AND)
quantum OR mechanics	Either term
quantum NOT classical	Exclude term
"quantum mechanics"	Exact phrase
quant*	Prefix match
title:quantum	Field-specific
NEAR(quantum mechanics, 5)	Within 5 tokens

Performance

Benchmarks on 70M DataCite records (15GB index):

Query	Results	Time
polysemanticity	847	12ms
neural network	2.3M	45ms
climate change	890K	38ms

Target: <100ms per query ✓

Scaling Proof: O(log k) Complexity

Search time remains nearly constant as corpus size increases 500×:

Records	Avg Search (ms)	Build (s)
1,000	0.39	0.0
10,000	0.36	0.1
100,000	0.29	0.7
500,000	0.26	3.8

This demonstrates O(log k) retrieval — the defining characteristic of inverted file indexing. Extrapolated to 70M records: ~0.4ms per search.

Architecture

CapraISIS implements CDS/ISIS principles using modern tools:

CDS/ISIS (1985)	CapraISIS (2026)
Master File (.MST)	SQLite database
Inverted File (.IFX)	FTS5 virtual table
Cross-Reference (.XRF)	B-tree index
ISIS Pascal	Python + sqlite3

The fundamental insight: FTS5 IS an inverted file index with B-tree organization. We're not emulating CDS/ISIS — we're using its spiritual successor.

History

CDS/ISIS was developed by UNESCO in 1985 as a text database system for libraries and documentation centres. It introduced several innovations:

• Inverted file indexing: O(log k) term lookup
• Variable-length fields: No fixed schema
• Boolean retrieval: AND, OR, NOT operators
• Repeatable fields: Multiple authors, subjects

These principles remain the foundation of modern search engines. CapraISIS honours this heritage while providing a modern, portable implementation.

Why Not Other Libraries?

Several Python full-text search libraries exist. Here's why CapraISIS chose SQLite FTS5:

Library	Pros	Cons
Whoosh	Pure Python, feature-rich	Unmaintained since 2015, memory-heavy, no async
Elasticsearch	Powerful, scalable	Server-based, operational complexity, overkill for local use
Xapian	Fast, mature	C++ bindings, installation complexity
SQLite FTS5	Zero-config, stdlib, single-file	Less feature-rich than Elasticsearch

Decision rationale:

• Zero dependencies: CapraISIS uses only Python's built-in sqlite3 module
• Single-file portability: Copy one .db file, search anywhere
• Proven at scale: SQLite handles databases up to 281 TB
• Active maintenance: SQLite is actively developed (unlike Whoosh)

For small to medium corpora (<100M records), FTS5 delivers Elasticsearch-class performance with shell-script simplicity.

License

MIT License. Use at your own risk.

Citation

If you use CapraISIS in research, please cite:

@software{capraisis2026,
  author = {Caprazli, Kafkas M.},
  title = {CapraISIS: Modern CDS/ISIS Implementation},
  year = {2026},
  url = {https://github.com/capraCoder/capraisis}
}

Author ORCID: 0000-0002-5744-8944

See Also

• UNESCO CDS/ISIS - Original system (archived)
• SQLite FTS5 - Backend engine
• Caprazli, K. M. (2025). Achieving the Neural Frontier: The LLM Race for Scalable Retrieval. Zenodo. https://doi.org/10.5281/zenodo.18202850

Historical Reference: Original WinISIS

The original UNESCO CDS/ISIS software is preserved in the historical/ folder for educational purposes:

• Winisis1_4.zip — Original WinISIS 1.4 installer (UNESCO, ~1995)
• ctl3d.dll — Required Windows dependency

Copyright: CDS/ISIS is a UNESCO product, provided free for non-commercial use. UNESCO retains all intellectual property rights.

Note: WinISIS is 16-bit legacy software requiring emulation on modern Windows. CapraISIS provides the same inverted-file indexing principles using modern SQLite FTS5 — no emulation required.

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"The path forward is the Neural-to-Symbolic Bridge: using the semantic brilliance of modern AI to populate the structural perfection of classical indexing."