## TL;DR

You passed --limit 0 or a negative number, or a variable feeding --limit resolved to one. Pass a positive integer like --limit 5. If the limit comes from a var, check the var value.

## Error

```text
dbt show error: limit must be positive
```

## Steps

1. Look at your dbt show invocation and find the --limit value.
   Expected: You see --limit 0, a negative number, or a var reference.

2. Replace it with a positive integer: dbt show --select my_model --limit 5.
   Expected: The command runs and prints sample rows.

3. If the limit came from a var or env var, print its resolved value and fix the source.
   Expected: The variable resolves to a positive integer.

4. Re-run dbt show and confirm you get the expected row sample.
   Expected: Sample rows print; no limit error.

## When to use

- dbt show fails with limit must be positive
- a script wraps dbt show and passes a computed limit
- the limit comes from an environment variable that is unset or zero

## When not to use

- the shown query itself errors (that is a SQL problem in the model)
- you want all rows (dbt show always limits; use a warehouse query for full output)
- dbt show fails to compile the model (fix the model first)

## Tool compatibility

- dbt-core 1.5+ (dbt show command)
- dbt Cloud IDE has its own preview; this is the CLI command
- --limit accepts any positive integer

## Variant phrasings

### limit must be positive with --limit 0
Zero is not positive. There is no way to show zero rows meaningfully; use 1 if you only want the schema.

### limit error only in a wrapper script
The script computes the limit; log the computed value before calling dbt show to see the bad input.

## Why it happens

dbt show compiles the model and runs it with a LIMIT clause for preview. A non-positive limit is rejected up front because the warehouse would either error or return nothing useful. The validation is protecting you from a meaningless preview.

## Edge cases

- Some warehouses treat LIMIT 0 as valid SQL returning no rows; dbt rejects it anyway at the CLI layer, so do not rely on warehouse behavior.
- dbt show --inline with custom SQL validates the limit the same way.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_T9pwLBRU5csj7OBDn2e_Qw