diff --git a/.circleci/run_tests.sh b/.circleci/run_tests.sh
index 4ba497c3..3e076c06 100644
--- a/.circleci/run_tests.sh
+++ b/.circleci/run_tests.sh
@@ -10,7 +10,7 @@ set -o xtrace
 # for inspection.
 function start_pgcat() {
     kill -s SIGINT $(pgrep pgcat) || true
-    RUST_LOG=${1} ./target/debug/pgcat .circleci/pgcat.toml &
+    ./target/debug/pgcat .circleci/pgcat.toml --log-level ${1} &
     sleep 1
 }
 
@@ -29,6 +29,9 @@ PGPASSWORD=sharding_user pgbench -h 127.0.0.1 -U sharding_user shard2 -i
 LOG_LEVEL=error toxiproxy-server &
 sleep 1
 
+# Remove toxiproxy if it exists.
+toxiproxy-cli delete postgres_replica || true
+
 # Create a database at port 5433, forward it to Postgres
 toxiproxy-cli create -l 127.0.0.1:5433 -u 127.0.0.1:5432 postgres_replica
 
diff --git a/src/client.rs b/src/client.rs
index 98a0669c..4989f8e3 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -890,7 +890,7 @@ where
 
                 'Q' => {
                     if query_router.query_parser_enabled() {
-                        match query_router.parse(&message) {
+                        initial_parsed_ast = Some(match query_router.parse(&message) {
                             Ok(ast) => {
                                 let plugin_result = query_router.execute_plugins(&ast).await;
 
@@ -910,15 +910,20 @@ where
 
                                 let _ = query_router.infer(&ast);
 
-                                initial_parsed_ast = Some(ast);
+                                ast
                             }
                             Err(error) => {
-                                warn!(
-                                    "Query parsing error: {} (client: {})",
-                                    error, client_identifier
-                                );
+                                if error != Error::UnsupportedStatement {
+                                    warn!(
+                                        "Query parsing error: {} (client: {})",
+                                        error, client_identifier
+                                    );
+                                }
+                                // Returning an empty vector shows the failed parse attempt and
+                                // avoids another round of parse attempt below.
+                                vec![]
                             }
-                        }
+                        })
                     }
                 }
 
@@ -940,10 +945,12 @@ where
                                 let _ = query_router.infer(&ast);
                             }
                             Err(error) => {
-                                warn!(
-                                    "Query parsing error: {} (client: {})",
-                                    error, client_identifier
-                                );
+                                if error != Error::UnsupportedStatement {
+                                    warn!(
+                                        "Query parsing error: {} (client: {})",
+                                        error, client_identifier
+                                    );
+                                }
                             }
                         };
                     }
@@ -1273,14 +1280,25 @@ where
                         if query_router.query_parser_enabled() {
                             // We don't want to parse again if we already parsed it as the initial message
                             let ast = match initial_parsed_ast {
-                                Some(_) => Some(initial_parsed_ast.take().unwrap()),
+                                Some(_) => {
+                                    let parsed_ast = initial_parsed_ast.take().unwrap();
+                                    // if 'parsed_ast' is empty, it means that there was a failed
+                                    // attempt to parse the query as a custom command, earlier above.
+                                    if parsed_ast.is_empty() {
+                                        None
+                                    } else {
+                                        Some(parsed_ast)
+                                    }
+                                }
                                 None => match query_router.parse(&message) {
                                     Ok(ast) => Some(ast),
                                     Err(error) => {
-                                        warn!(
-                                            "Query parsing error: {} (client: {})",
-                                            error, client_identifier
-                                        );
+                                        if error != Error::UnsupportedStatement {
+                                            warn!(
+                                                "Query parsing error: {} (client: {})",
+                                                error, client_identifier
+                                            );
+                                        }
                                         None
                                     }
                                 },
diff --git a/src/query_router.rs b/src/query_router.rs
index 8b451dd3..4b6873dc 100644
--- a/src/query_router.rs
+++ b/src/query_router.rs
@@ -338,6 +338,9 @@ impl QueryRouter {
         Some((command, value))
     }
 
+    const UNSUPPORTED_STATEMENTS_FOR_PARSING: [&'static str; 4] =
+        ["COPY", "SET", "TRUNCATE", "VACUUM"];
+
     pub fn parse(&self, message: &BytesMut) -> Result<Vec<Statement>, Error> {
         let mut message_cursor = Cursor::new(message);
 
@@ -380,8 +383,22 @@ impl QueryRouter {
         match Parser::parse_sql(&PostgreSqlDialect {}, &query) {
             Ok(ast) => Ok(ast),
             Err(err) => {
-                debug!("{}: {}", err, query);
-                Err(Error::QueryRouterParserError(err.to_string()))
+                let qry_upper = query.to_ascii_uppercase();
+
+                // Check for unsupported statements to avoid producing a warning.
+                // Note 1: this is not a complete list of unsupported statements.
+                // Note 2: we do not check for unsupported statements before going through the
+                //         parser, as the plugin system might be able to handle them, once sqlparser
+                //         is able to correctly parse these (rather valid) queries.
+                if Self::UNSUPPORTED_STATEMENTS_FOR_PARSING
+                    .iter()
+                    .any(|s| qry_upper.starts_with(s))
+                {
+                    Err(Error::UnsupportedStatement)
+                } else {
+                    debug!("{}: {}", err, query);
+                    Err(Error::QueryRouterParserError(err.to_string()))
+                }
             }
         }
     }
diff --git a/tests/docker/run.sh b/tests/docker/run.sh
index ae30c978..bfffc570 100644
--- a/tests/docker/run.sh
+++ b/tests/docker/run.sh
@@ -1,6 +1,18 @@
 #!/bin/bash
 
-rm -rf /app/target/ || true
+set -e
+
+CLEAN_BUILD=true
+
+if [ $1 = "no-clean" ]; then
+    echo "INFO: clean build is NOT going to be performed."
+    CLEAN_BUILD=false
+    find /app/target/debug/deps -name *.gcda  -exec rm {} \;
+fi
+
+if $CLEAN_BUILD ; then
+    rm -rf /app/target/ || true
+fi
 rm /app/*.profraw || true
 rm /app/pgcat.profdata || true
 rm -rf /app/cov || true
@@ -12,7 +24,9 @@ export RUSTFLAGS="-Zprofile -Ccodegen-units=1 -Copt-level=0 -Clink-dead-code -Co
 export RUSTDOCFLAGS="-Cpanic=abort"
 
 cd /app/
-cargo clean
+if $CLEAN_BUILD ; then
+    cargo clean
+fi
 cargo build
 cargo test --tests
 
diff --git a/tests/pgbench/simple.sql b/tests/pgbench/simple.sql
index ad5e6139..8a01cb4a 100644
--- a/tests/pgbench/simple.sql
+++ b/tests/pgbench/simple.sql
@@ -26,7 +26,7 @@ UPDATE pgbench_branches SET bbalance = bbalance + :delta WHERE bid = :bid;
 
 INSERT INTO pgbench_history (tid, bid, aid, delta, mtime) VALUES (:tid, :bid, :aid, :delta, CURRENT_TIMESTAMP);
 
-END;
+COMMIT;
 
 SET SHARDING KEY TO :aid;