docs: logical operators (#308)

* docs: logical operators

* Address feedback

Author: saihaj

website/pages/en/querying/graphql-api.mdx

@@ -168,6 +168,58 @@ This can be useful if you are looking to fetch only entities whose child-level e
 }
 ```
 
+#### Logical operators
+
+As of Graph Node [`v0.30.0`](https://github.com/graphprotocol/graph-node/releases/tag/v0.30.0) you can group multiple parameters in the same `where` argument using the `and` or the `or` operators to filter results based on more than one criteria.
+
+##### `AND` Operator
+
+In the following example, we are filtering for challenges with `outcome` `succeeded` and `number` greater than or equal to `100`.
+
+```graphql
+{
+  challenges(where: { and: [{ number_gte: 100 }, { outcome: "succeeded" }] }) {
+    challenger
+    outcome
+    application {
+      id
+    }
+  }
+}
+```
+
+> **Syntactic sugar:** You can simplify the above query by removing the `and` operator by passing a sub-expression separated by commas.
+>
+> ```graphql
+> {
+>   challenges(where: { number_gte: 100, outcome: "succeeded" }) {
+>     challenger
+>     outcome
+>     application {
+>       id
+>     }
+>   }
+> }
+> ```
+
+##### `OR` Operator
+
+In the following example, we are filtering for challenges with `outcome` `succeeded` or `number` greater than or equal to `100`.
+
+```graphql
+{
+  challenges(where: { or: [{ number_gte: 100 }, { outcome: "succeeded" }] }) {
+    challenger
+    outcome
+    application {
+      id
+    }
+  }
+}
+```
+
+> **Note**: When constructing queries, it is important to consider the performance impact of using the `or` operator. While `or` can be a useful tool for broadening search results, it can also have significant costs. One of the main issues with `or` is that it can cause queries to slow down. This is because `or` requires the database to scan through multiple indexes, which can be a time-consuming process. To avoid these issues, it is recommended that developers use and operators instead of or whenever possible. This allows for more precise filtering and can lead to faster, more accurate queries.
+
 #### All Filters
 
 Full list of parameter suffixes: