---
title: approx_count() | Tiger Data Docs
description: Estimate the number of times a value appears from a `CountMinSketch`
---

Early access [1.8.0](https://github.com/timescale/timescaledb-toolkit/releases/tag/1.8.0)

Estimate the number of times a given text value appears in a column.

## Samples

Given a table of stock data, estimate how many times the symbol `AAPL` appears:

```
WITH t AS (
  SELECT toolkit_experimental.count_min_sketch(symbol, 0.01, 0.01) AS symbol_sketch
  FROM crypto_ticks
)
SELECT toolkit_experimental.approx_count('AAPL', symbol_sketch)
FROM t;
```

## Arguments

The syntax is:

```
approx_count (
    item TEXT,
    agg CountMinSketch
) RETURNS BIGINT
```

| Name   | Type           | Default | Required | Description                                                                                                                                         |
| ------ | -------------- | ------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| `item` | TEXT           | -       | ✔        | The value you want to estimate occurrences of                                                                                                       |
| `agg`  | CountMinSketch | -       | ✔        | A `CountMinSketch` object created using [`count_min_sketch`](/docs/reference/toolkit/frequency-analysis/count_min_sketch/count_min_sketch/index.md) |

## Returns

| Column        | Type   | Description                                                 |
| ------------- | ------ | ----------------------------------------------------------- |
| approx\_count | BIGINT | The estimated number of times `item` appeared in the sketch |