Test benchmarks and Improve benchmark README.md (#1627)

Author: alamb

.github/workflows/rust.yml

@@ -37,6 +37,14 @@ jobs:
         uses: ./.github/actions/setup-builder
       - run: cargo clippy --all-targets --all-features -- -D warnings
 
+  benchmark-lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Rust Toolchain
+        uses: ./.github/actions/setup-builder
+      - run: cd sqlparser_bench && cargo clippy --all-targets --all-features -- -D warnings
+
   compile:
     runs-on: ubuntu-latest
     steps:

sqlparser_bench/README.md

@@ -17,4 +17,26 @@
   under the License.
 -->
 
-Benchmarks for sqlparser. See [the main README](../README.md) for more information.
+Benchmarks for sqlparser. See [the main README](../README.md) for more information.
+
+Note: this is in a separate, non workspace crate to avoid adding a dependency 
+on `criterion` to the main crate (which complicates testing without std).
+
+# Running Benchmarks
+
+```shell
+cargo bench --bench sqlparser_bench
+```
+
+# Profiling
+
+Note you can generate a [flamegraph] using the following command:
+
+```shell
+cargo flamegraph --bench sqlparser_bench
+```
+
+[flamegraph]: https://crates.io/crates/flamegraph
+
+Here is an example flamegraph:
+![flamegraph](img/flamegraph.svg)