Tag: data-engineering

The demo works. It always does. You call AI_CLASSIFY on a sample of 10,000 rows, the credits barely move, and someone in the room says “this is so much cheaper than sending data to an external API.” Three weeks later your first real workload hits production — a million rows, five label classes, a moderately verbose model — and the bill is three times what you modelled. Nobody touched the model. Nobody changed the prompt. The data volume was planned. What went wrong?

The short answer: Snowflake Cortex AI has three independent cost meters running in parallel, and two of them are nearly invisible until you go looking. The warehouse credit line your resource monitors watch? That’s only one of the three. The other two — AI token consumption and always-on serving compute — accumulate quietly in tables most engineers haven’t queried yet.

After the April 2026 introduction of AI Credits as a separate billing currency, the gap between what teams expect to pay and what actually lands on the invoice got wider, not narrower. This piece maps exactly where the hidden costs live, shows you the math on each one, and gives you the SQL to surface them before your finance team does.

TL;DR

• Snowflake Cortex AI bills across three independent meters — warehouse compute, AI token consumption, and serving compute — and resource monitors only cover the first one.
• Functions like AI_CLASSIFY, AI_SENTIMENT, and AI_SUMMARIZE silently inject a system prompt before your text, so the billed token count is always higher than the text you actually sent.
• For AI_CLASSIFY, your label list is counted as input tokens for every single row processed, not once per call — a five-class classifier with verbose descriptions can multiply your expected token count by 2–4×.
• Cortex Search charges a continuous serving-compute fee per GB of indexed data per month, regardless of whether any queries are running — a 70 GB corpus costs roughly $882/month at rest.
• As of April 2026, AI Features bill in AI Credits ($2.00 global / $2.20 regional), which are separate from Platform Credits; the two currency types can coexist on the same bill and require different monitoring queries.
• Query SNOWFLAKE.ACCOUNT_USAGE.CORTEX_FUNCTIONS_USAGE_HISTORY per function and model to find your real cost breakdown; do not try to sum multiple overlapping views or you will double-count.
• Model selection is still the single largest cost lever — the same classification workload can differ by 10–60× in price depending on which model you choose.

Why the Demo Lied to You

The confusion starts with how Snowflake traditionally teaches cost intuition. For years, the mental model was: bigger warehouse = more credits = more cost. You learned to right-size warehouses, use auto-suspend, and watch the METERING_HISTORY view. That model works fine for compute-heavy SQL. It actively misleads you for Cortex AI.

When you run a Cortex AI function, the warehouse compute cost still applies — your VWH is active while the query runs, so those credits accumulate. But the AI token charges are separate, billed in a different currency against a different meter, and they show up in different Account Usage views. A demo on a SMALL warehouse processing 10,000 rows barely registers on either meter. A production run of one million rows with a frontier model is a completely different animal.

One well-documented real-world example: a team processed 1.18 billion records using Cortex Functions and received a single-query bill of nearly $5,000 — almost entirely from token costs, with minimal warehouse compute. Their resource monitors never triggered because resource monitors don’t watch the AI token meter. The bill simply appeared.

The April 2026 billing restructure added another wrinkle. Snowflake introduced AI Credits as a separate billing currency, flat-priced at $2.00 per credit for global routing or $2.20 for regional routing, independent of your Snowflake edition. This means an Enterprise customer and a Standard customer pay exactly the same rate for AI inference — but the two credit types appear as separate line items and require separate monitoring logic. If you built a cost dashboard before April 2026, it is almost certainly incomplete.

The Token Inflation You’re Not Accounting For

Most engineers assume “tokens billed = tokens in my text.” For AI_COMPLETE with a hand-written prompt that assumption is roughly correct. For the structured AI functions — AI_CLASSIFY, AI_SENTIMENT, AI_FILTER, AI_AGG, AI_SUMMARIZE, AI_TRANSLATE — it is wrong in ways the documentation buries in a footnote.

According to Snowflake’s official cost documentation, these functions add a system prompt to your input text before sending it to the model. The billed token count is therefore always higher than the number of tokens in the text you provide. You pay for the system prompt on every row. You have no visibility into how long that system prompt is. You cannot opt out.

For AI_CLASSIFY specifically, the hidden cost compounds further: your label list, descriptions, and examples are counted as input tokens for every record processed, not once per call. If you have five label classes with 30-word descriptions each, you’re paying for roughly 150 extra tokens on every single row. Run that against a million-row table and you’ve added 150 million tokens of cost that had nothing to do with your data.

The fix is to measure before you scale. Snowflake provides a AI_COUNT_TOKENS function that reports token counts without incurring LLM charges — use it on a sample to calibrate your label overhead before committing to a full-table run:

-- Estimate label overhead before running AI_CLASSIFY at scale
SELECT
  COUNT(*) AS sample_rows,
  AVG(SNOWFLAKE.CORTEX.AI_COUNT_TOKENS(
    'llama3.1-8b',
    your_text_column
  )) AS avg_text_tokens,
  -- Add your label string manually to see the combined token count
  AVG(SNOWFLAKE.CORTEX.AI_COUNT_TOKENS(
    'llama3.1-8b',
    your_text_column || ' CATEGORIES: positive, negative, neutral, urgent, spam'
  )) AS avg_with_labels_tokens
FROM your_table
LIMIT 5000;

The gap between avg_text_tokens and avg_with_labels_tokens is your label overhead per row. Multiply by row count and by the per-million-token rate for your chosen model to get a cost estimate before you fire the real query. This takes five minutes and can prevent a four-figure surprise.

The Two-Currency Problem

Before you can build a cost dashboard, you need to understand which features bill in which currency — because the monitoring SQL differs by type.

The important detail: Cortex AI Functions like AI_COMPLETE stack two meters simultaneously. You pay AI Credits for the tokens, and you pay Platform Credits for the warehouse time your query consumed. A query that takes 30 seconds on a MEDIUM warehouse and processes 500,000 tokens is billing on two completely separate ledgers. Neither one cancels the other. Snowflake’s recommendation is to use no larger than a MEDIUM warehouse for Cortex AI calls, because a larger warehouse doesn’t speed up token processing — it just burns more Platform Credits for the same result.

The Cortex Search Idle Tax

Cortex Search is architecturally different from the AI SQL functions. It’s a managed vector-search service: you create a search service over a table, Snowflake indexes it, and you query it via a REST call or through Cortex Agents. The billing model reflects this — and it’s the most surprising line item for teams that build and then deprioritize a search-based RAG feature.

Cortex Search’s serving compute bills continuously per GB of indexed data per month, while the service is resumed — whether or not any queries are running. The Snowflake pricing documentation confirms this: “A running search service incurs costs even when it isn’t serving queries.” Based on the Service Consumption Table, the serving rate is 6.3 AI Credits per GB per month. At the global AI Credit price of $2.00, that’s $12.60 per GB per month, every month, at rest.

Run the math for a team that has multiple Cortex Search services:

The dev service row is where most teams first notice the problem. Someone spun up a search service in a development environment to prototype a chatbot, the project shifted priorities, and the service kept running. It doesn’t consume query tokens because nobody’s hitting it. It consumes serving compute because it exists. That’s $378/month for a service that produced zero output in that billing period.

The mitigation is straightforward: configure AUTO_SUSPEND on any search service that has predictable idle windows, and manually suspend development services when a feature is deprioritised. Snowflake Batch Search is an alternative for workloads that don’t need real-time retrieval — its serving compute runs only during the batch job, not continuously.

Cortex Agents: The Cost Multiplier Nobody Drew on the Whiteboard

Cortex Agents are billed per million tokens, in AI Credits, with rates determined by the underlying model. That sounds simple. The complication is that agents orchestrate multi-step workflows, and every step that invokes a sub-service generates its own token consumption. Snowflake’s official pricing docs state it directly: costs are additive across the underlying services the agent invokes.

A realistic agent loop might look like this: the agent receives a user question (input tokens), calls Cortex Search to retrieve context (embedding tokens + serving compute), calls Cortex Analyst to generate SQL (Analyst tokens), executes the SQL on a warehouse (Platform Credits), and then calls an LLM to formulate a final answer (more input + output tokens). Every hop generates its own consumption. The result visible to the user is a single response. The result visible to your billing dashboard is five separate line items, split across two credit types, spread across four different usage views.

Standard monitoring via CORTEX_FUNCTIONS_USAGE_HISTORY does not provide agent-specific breakdowns. To get token-level visibility per agent, you need to query SNOWFLAKE.LOCAL.AI_OBSERVABILITY_EVENTS — a system table that captures token counts, models used, timing, and execution context for each agent invocation. That table is not surfaced by default in the Snowflake UI; you have to query it directly.

-- Per-agent token cost attribution
-- Requires ACCOUNTADMIN or SNOWFLAKE_TELEMETRY privilege
SELECT
  agent_name,
  model_name,
  DATE_TRUNC('day', event_timestamp) AS event_day,
  SUM(input_tokens)                  AS total_input_tokens,
  SUM(output_tokens)                 AS total_output_tokens,
  SUM(input_tokens + output_tokens)  AS total_tokens
FROM SNOWFLAKE.LOCAL.AI_OBSERVABILITY_EVENTS
WHERE event_timestamp >= CURRENT_DATE - 30
GROUP BY 1, 2, 3
ORDER BY total_tokens DESC;

For AI SQL functions, your canonical daily monitoring query should look like this:

-- Cortex AI function cost by model and function — last 30 days
-- Use CORTEX_FUNCTIONS_USAGE_HISTORY as the single source; do NOT sum
-- across CORTEX_AISQL_USAGE_HISTORY and CORTEX_FUNCTIONS_USAGE_HISTORY together
SELECT
  DATE_TRUNC('day', start_time)   AS usage_day,
  function_name,
  model_name,
  SUM(input_tokens)               AS input_tokens,
  SUM(output_tokens)              AS output_tokens,
  SUM(credits_used)               AS ai_credits,
  ROUND(SUM(credits_used) * 2.00, 2) AS est_cost_usd
FROM SNOWFLAKE.ACCOUNT_USAGE.CORTEX_FUNCTIONS_USAGE_HISTORY
WHERE start_time >= CURRENT_DATE - 30
GROUP BY 1, 2, 3
ORDER BY ai_credits DESC;

One critical warning from Snowflake’s own community documentation: the views CORTEX_AISQL_USAGE_HISTORY, CORTEX_FUNCTIONS_USAGE_HISTORY, and an incremental metering path all overlap. Summing them produces double-counts. Pick one canonical view per service type and reconcile totals against the matching service type in METERING_DAILY_HISTORY.

Non-Text Inputs: The Per-Page and Per-Second Trap

If your team is using Cortex for document intelligence — contract review, PDF extraction, audio transcription — the token model changes again. AI_PARSE_DOCUMENT and AI_EXTRACT bill by page rather than by text token: each page in a document counts as 970 tokens. A 50-page contract isn’t 50 pages of your text column — it’s 48,500 tokens before a single word of your prompt or the model’s output enters the meter.

Audio inputs bill at 50 tokens per second of audio. A one-hour customer support call is 180,000 audio tokens before output tokens are added. At frontier model rates, an hour of audio can cost more than a thousand-word document by a wide margin.

The implication for pipeline design: always pre-filter. Before sending a document to AI_EXTRACT, check page count. Before sending audio to a transcription function, check duration. For PDFs specifically, page-level sampling — sending only the pages likely to contain the target information — can reduce cost by 60–80% compared to sending the full document.

The Gotchas Nobody Warns You About

Your existing resource monitors don’t cover AI token spend.Resource monitors in Snowflake watch warehouse compute credits. They have no visibility into AI Credit consumption. A runaway AI_CLASSIFY job on a large table will not trigger your existing budget alerts. You need separate alerting built on CORTEX_FUNCTIONS_USAGE_HISTORY and wired to a Snowflake Task and notification integration.

The regional routing setting silently raises every AI bill by 10%.If your account has CORTEX_ENABLED_CROSS_REGION set to DISABLED or a specific regional setting for data residency, you’re paying $2.20 per AI Credit instead of $2.00. That’s a 10% tax on every token across every Cortex AI feature, and it’s an account-level parameter many teams set once during a compliance review and never revisit against their cost model.

Cortex Analyst through the standalone API still bills in Platform Credits, not AI Credits.If you’re calling Cortex Analyst via the REST API directly rather than through Cortex Agents, it bills per 1,000 messages at Platform Credit rates — which vary by your Snowflake edition. The same Analyst call made through a Cortex Agent costs in AI Credits. The same feature, two different billing regimes, depending on how you invoke it.

Materializing AI results is almost always cheaper than recomputing them.Teams building pipelines that call AI_CLASSIFY or AI_SENTIMENT inside a scheduled task often reprocess unchanged records on every run. The AI functions have no inherent awareness of which records changed since the last run. Join against your source table’s UPDATED_AT column, write results to a separate table, and only pass new or modified rows to the AI function. This pattern, applied consistently, can reduce ongoing AI Credit consumption by 50–90% for stable datasets.

The Cortex Guard security layer adds its own token cost on top of AI_COMPLETE.If you’re using Cortex Guard to filter model outputs for safety — which is sensible for user-facing applications — it bills separately from the underlying AI_COMPLETE call. The input token count for Cortex Guard is based on the number of tokens in AI_COMPLETE’s output. In other words, longer model responses cost more not once but twice: once when generated, and again when scanned by the guard.

The One Principle

“Treat Cortex AI cost engineering the same way you treat warehouse sizing — measure before you scale, not after. The token meter doesn’t have a circuit breaker unless you build one.”

Related reading: Cortex Search RAG guide · Cortex Code and dbt optimization · Governing AI Agents in Snowflake · AI coding agents and pipeline security · What actually works when building AI agents · Snowflake Cortex AI cost docs (official) · Snowflake AI pricing and AI Credits (official)