---
title: "EXPLAIN"
sidebarTitle: "Explain"
description: "Reading the plan for a statement, and measuring it."
icon: map
keywords: ["explain", "explain analyze", "query plan", "describe"]
---

<Badge color="red">Enterprise</Badge> [SQL runs on a deployment.](/sql)

```sql
EXPLAIN SELECT * FROM documents WHERE identifier < 1000
EXPLAIN ANALYZE SELECT * FROM documents WHERE identifier < 1000
```

`EXPLAIN` resolves the plan without running the query. `EXPLAIN ANALYZE`
executes it and annotates every operator with runtime metrics — elapsed time,
rows produced, bytes read, index comparisons.

The operators are the same ones the SDK methods produce, so the reasoning about
index coverage and filter pushdown carries across unchanged. The two pages that
explain how to read them:

<CardGroup cols={2}>
  <Card title="Explain" icon="map" href="/search/explain">
    Reading a plan: operators, pushdown, index usage.
  </Card>
  <Card title="Explain Analyze" icon="gauge" href="/search/explain-analyze">
    Reading the metrics, and a worked before/after.
  </Card>
</CardGroup>

## What to look for {#what-to-look-for}

| Sign | Means |
| --- | --- |
| `ScalarIndexQuery` | the predicate used a scalar index |
| `LanceScan` with high `bytes_read` | no index, or too many columns selected |
| `FilterExec` above a search | the filter ran after search rather than pushing into it |
| `ANNSubIndex` / `ANNIvfPartition` | the vector index was used |

A `LanceScan` feeding a join is the common one worth acting on — see
[Joins](/sql/join#performance).

## DESCRIBE {#describe}

```sql
DESCRIBE documents
```

The table's columns and types, without a plan.