# Querying Pinot

## SQL Interface

Pinot provides a SQL interface for querying, which uses the **Calcite SQL** parser to parse queries and the **MYSQL\_ANSI** dialect. For details on the syntax, see the the [Calcite documentation](https://calcite.apache.org/docs/reference.html). To find supported SQL operators, see [Class SqlLibraryOperators](https://calcite.apache.org/javadocAggregate/org/apache/calcite/sql/fun/SqlLibraryOperators.html).

## Pinot 1.0

In Pinot 1.0, the multi-stage query engine supports inner join, left-outer, semi-join, and nested queries out of the box. It's optimized for in-memory process and latency. For more information, see how to [enable and use the multi-stage query engine](https://docs.pinot.apache.org/release-1.1.0/for-developers/advanced/v2-multi-stage-query-engine).

Pinot also supports using simple Data Definition Language (DDL) to insert data into a table from file directly. For details, see [programmatically access the multi-stage query engine](https://docs.pinot.apache.org/release-1.1.0/for-developers/advanced/v2-multi-stage-query-engine#programmatically-access-the-multi-stage-query-engine). More DDL supports will be added in the future. But for now, the most common way for data definition is using the [Controller Admin API](https://docs.pinot.apache.org/users/api/pinot-rest-admin-interface).

{% hint style="info" %}
**Note:** For queries that require a large amount of data shuffling, require spill-to-disk, or are hitting any other limitations of the multi-stage query engine (v2), we still recommend using **Presto**.
{% endhint %}

## Identifier vs Literal

In Pinot SQL:

* **Double quotes(")** are used to force string identifiers, e.g. column names
* **Single quotes(')** are used to enclose string literals. If the string literal also contains a single quote, escape this with a single quote e.g `'''Pinot'''` to match the string literal `'Pinot'`

Misusing those might cause unexpected query results, like the following examples:

* `WHERE a='b'` means the predicate on the column `a` equals to a string literal value `'b'`
* `WHERE a="b"` means the predicate on the column `a` equals to the value of the column `b`

If your column names use reserved keywords (e.g. `timestamp` or `date`) or special characters, you will need to use double quotes when referring to them in queries.

Note: Define decimal literals within quotes to preserve precision.

## Example Queries

### Selection

```
//default to limit 10
SELECT * 
FROM myTable 

SELECT * 
FROM myTable 
LIMIT 100
```

```
SELECT "date", "timestamp"
FROM myTable 
```

### Aggregation

```sql
SELECT COUNT(*), MAX(foo), SUM(bar) 
FROM myTable
```

### Grouping on Aggregation

```sql
SELECT MIN(foo), MAX(foo), SUM(foo), AVG(foo), bar, baz 
FROM myTable
GROUP BY bar, baz 
LIMIT 50
```

### Ordering on Aggregation

```sql
SELECT MIN(foo), MAX(foo), SUM(foo), AVG(foo), bar, baz 
FROM myTable
GROUP BY bar, baz 
ORDER BY bar, MAX(foo) DESC 
LIMIT 50
```

### Filtering

```sql
SELECT COUNT(*) 
FROM myTable
  WHERE foo = 'foo'
  AND bar BETWEEN 1 AND 20
  OR (baz < 42 AND quux IN ('hello', 'goodbye') AND quuux NOT IN (42, 69))
```

For performant filtering of IDs in a list, see [Filtering with IdSet](https://docs.pinot.apache.org/users/user-guide-query/filtering-with-idset).

### Filtering with NULL predicate

```sql
SELECT COUNT(*) 
FROM myTable
  WHERE foo IS NOT NULL
  AND foo = 'foo'
  AND bar BETWEEN 1 AND 20
  OR (baz < 42 AND quux IN ('hello', 'goodbye') AND quuux NOT IN (42, 69))
```

### Selection (Projection)

```sql
SELECT * 
FROM myTable
  WHERE quux < 5
  LIMIT 50
```

### Ordering on Selection

```sql
SELECT foo, bar 
FROM myTable
  WHERE baz > 20
  ORDER BY bar DESC
  LIMIT 100
```

### Pagination on Selection

Note that results might not be consistent if the `ORDER BY` column has the same value in multiple rows.

```sql
SELECT foo, bar 
FROM myTable
  WHERE baz > 20
  ORDER BY bar DESC
  LIMIT 50, 100
```

### Wild-card match (in WHERE clause only)

The example below counts rows where the column `airlineName` starts with `U`:

```sql
SELECT COUNT(*) 
FROM myTable
  WHERE REGEXP_LIKE(airlineName, '^U.*')
  GROUP BY airlineName LIMIT 10
```

### Case-When Statement

Pinot supports the `CASE-WHEN-ELSE` statement, as shown in the following two examples:

```sql
SELECT
    CASE
      WHEN price > 30 THEN 3
      WHEN price > 20 THEN 2
      WHEN price > 10 THEN 1
      ELSE 0
    END AS price_category
FROM myTable
```

```sql
SELECT
  SUM(
    CASE
      WHEN price > 30 THEN 30
      WHEN price > 20 THEN 20
      WHEN price > 10 THEN 10
      ELSE 0
    END) AS total_cost
FROM myTable
```

### UDF

Pinot doesn't currently support injecting functions.  Functions have to be implemented within Pinot, as shown below:

```sql
SELECT COUNT(*)
FROM myTable
GROUP BY DATETIMECONVERT(timeColumnName, '1:MILLISECONDS:EPOCH', '1:HOURS:EPOCH', '1:HOURS')
```

For more examples, see [Transform Function in Aggregation Grouping](https://docs.pinot.apache.org/users/user-guide-query/supported-transformations).

### BYTES column

Pinot supports queries on BYTES column using hex strings. The query response also uses hex strings to represent bytes values.

The query below fetches all the rows for a given UID:

```sql
SELECT * 
FROM myTable
WHERE UID = 'c8b3bce0b378fc5ce8067fc271a34892'
```


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# Agent Instructions: Querying This Documentation

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Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
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```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.