README

dbase

A clean room implementation of dBase III and IV database suitable for low-memory computers like an XT

Features

Pascal Implementation (Memory Optimized)

• DBF.PAS - dBase III/IV file operations (8KB stack, 64KB heap)
• DBFINDEX.PAS - NDX index reading (8KB stack, 16KB heap)
• ASSERT.PAS - Unit testing framework
• Optimized for 8088/8086 systems with limited RAM

Python Implementation (Full Featured)

• dbf_module.py - Complete DBF file operations
• ndx_module.py - NDX index creation and searching
• dbf_query.py - Query optimization with heap maps
• assert_module.py - Testing utilities

Query Optimization

Two query systems available:

Simple Queries (dbf_query.py)

from dbf_query import DBFQueryBuilder

query = DBFQueryBuilder("games.DBF")
query.filter_by_ndx_prefix("title.NDX", "King")
query.filter_by_value("year", 1984)
recnos = query.execute()

Advanced Queries (dbf_query_v2.py)

from dbf_query_v2 import DBFQuery, FilterGroup, GroupOp, equal, like

query = DBFQuery("games.DBF")

# Group 1: Title filters (OR)
group1 = FilterGroup(GroupOp.OR)
group1.add_filter(like("title", "King", "title.NDX"))
group1.add_filter(like("title", "Queen", "title.NDX"))
query.add_group(group1)

# Group 2: Year and player filters (AND)
group2 = FilterGroup(GroupOp.AND)
group2.add_filter(equal("year", 1984))
group2.add_filter(equal("maxplay", 4))
query.add_group(group2)

recnos = query.execute()

Features:

• Up to 4 filter groups with OR/AND logic
• Up to 8 filters per group
• Unified heap map (33% memory savings)
• 40-160x faster than full table scans

See docs/QUERY_ARCHITECTURE.md for details.

Documentation

• README_dbf.md - DBF file format and operations
• README_ndx.md - NDX index format and searching
• QUERY_ARCHITECTURE.md - Advanced query system (v2)
• QUERY_MEMORY_ANALYSIS.md - Memory analysis for Pascal port
• QUERY_OPTIMIZATION.md - Simple query system (v1)
• PASCAL_MEMORY_NOTES.md - Memory optimization details
• IMPLEMENTATION_STATUS.md - Feature status

Testing

# Python tests
pytest tests/

# Keep test files for inspection
$env:KEEP_TEST_FILES=1
pytest tests/test_ndx_module.py

# Pascal tests (from tests directory)
fpc TESTDBF.PAS -Fu..
fpc TESTIDX.PAS -Fu..