Pretensor

What it is

A schema knowledge base for PostgreSQL, Snowflake and BigQuery. It introspects the database, builds a graph of tables, columns, foreign keys and inferred joins, and serves that graph to an agent — so schema questions are answered from the graph rather than from raw SQL against your warehouse.

What you get

• list_databases shows indexed connections with table counts and staleness, schema shows node labels and edge types
• query runs BM25 keyword search over table and entity metadata, upgrading to a hybrid BM25 + cosine rerank when embeddings are installed
• semantic_search ranks tables by cosine similarity, and returns a structured BM25-fallback envelope when the embeddings extra is absent
• context returns everything about one table — columns, joins, lineage, cluster metadata — and traverse finds join paths between two tables
• impact lists downstream tables reachable by foreign key and inferred-join edges, each carrying its external code consumers
• consumers names the service, file, line range, read/write op and confidence for code that touches a table, populated by pretensor analyze
• cypher runs read-only queries against the graph; mutating clauses are rejected
• detect_changes compares the live schema against the last indexed snapshot without mutating the graph
• compile_metric compiles semantic-layer YAML into validated SQL, and validate_sql checks SQL against the graph before you execute it

Requirements

Python 3.11 or 3.12. Published on PyPI as pretensor version 0.1.0. Database drivers are extras, not part of the base install — pip install 'pretensor[postgres]', [snowflake], [bigquery], or [all-connectors]; a bare install has no driver and fails at connect time. [embeddings] adds local ONNX embeddings and is what turns semantic_search from a fallback into real cosine ranking; [clustering] adds Leiden community detection. Usage is pretensor index against your database URL, then pretensor serve --config-only, which prints the client JSON to merge into your settings. --state-dir and --graph-dir override the default .pretensor directory. It is marked Beta, and the advice is to pin exact versions until 1.0.0.

Setup effort

Follow the published steps — pip install 'pretensor[postgres]'

Tools you get

12 tools named in the project's documentation. semantic_search always appears but falls back to BM25 ranking unless pretensor[embeddings] is installed and tables carry vectors.

Requires

Python 3.11 or 3.12 (3.13 not yet tested)

Where it runs

Both documented clients run the server on your machine.