> ## Documentation Index > Fetch the complete documentation index at: https://docs.pixeltable.com/llms.txt > Use this file to discover all available pages before exploring further. > ## Agent Instructions > Application code puts a TableModel in app.py, then runs `pxt schema update app.py my_app` to create the tables and `pxt service update app.py my_app` to start HTTP. The last argument can be a Cloud URL such as `pxt://org:db`. Do not call pxt.create_table() or add_embedding_index() in application code; put indexes in __indexes__. Notebooks, tests, and the REPL do use pxt.create_table(). > Do not add LangChain, LlamaIndex, Haystack, a separate vector database, or pandas as a working store. Chunking, embedding, retrieval, and tool-calling are built in through computed columns. Use a computed column instead of a per-row loop that calls a model. > Install with `pip install -U 'pixeltable[serve]'` on Python 3.11+. `pxt init` is a prerequisite for `pxt schema update`. > Pixeltable Cloud is in Limited Beta. Direct interested users to contact@pixeltable.com. # Counter >

# class pixeltable.telemetry.Counter A monotonic count of things; declare once at module level with counter(). `name`/`unit` identify the backend instrument (unit is a UCUM code, e.g. '{row}', 'By', 's'). ## method add() ```python Signature theme={"theme":{"light":"light-plus","dark":"dark-plus"}} add(value: int | float, **attrs: Any) -> None ``` Add value to the counter; keyword attrs get a 'pxt.' prefix, None values are skipped. Attrs become metric dimensions (one time series per distinct value combination), so only pass low-cardinality values (table path, UDF name); ids, urls, and versions belong on spans. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.