# Manual page CQ not correct mean on string

**URL:** <https://community.influxdata.com/t/manual-page-cq-not-correct-mean-on-string/7975>\
**Category:** Systems\
**Created:** [December 29, 2018, 12:52pm UTC](https://community.influxdata.com/t/manual-page-cq-not-correct-mean-on-string/7975 "2018-12-29T12:52:26Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![f1outsourcing](https://avatars.discourse-cdn.com/v4/letter/f/a183cd/32.png) [@f1outsourcing](https://community.influxdata.com/u/f1outsourcing)\
**Post date:** [December 29, 2018, 12:52pm UTC](https://community.influxdata.com/t/manual-page-cq-not-correct-mean-on-string/7975/1 "2018-12-29T12:52:26Z")

</div>

> **[Downsampling and data retention | InfluxDB OSS 1.7 Documentation](https://docs.influxdata.com/influxdb/v1.7/guides/downsampling_and_retention/)**
>
> InfluxDB can handle hundreds of thousands of data points per second. Working with that much data over a long period of time can create storage concerns. A natural solution is to downsample the data; keep the high precision raw data for only a limited...

```auto
> CREATE CONTINUOUS QUERY "cq_30m" ON "food_data" BEGIN
  SELECT mean("website") AS "mean_website",mean("phone") AS "mean_phone"
  INTO "a_year"."downsampled_orders"
  FROM "orders"
  GROUP BY time(30m)
END

```

If I do a mean on ‘string’ field, I am getting  
ERR: unsupported mean iterator type: \*query.stringInterruptIterator