From 880585947ab05049ab1826156f150953640325d7 Mon Sep 17 00:00:00 2001
From: Luis Neves <luis.neves@clickhouse.com>
Date: Wed, 10 Jun 2026 16:43:41 +0100
Subject: [PATCH] fix: splitter now supports explain

---
 crates/pgls_statement_splitter/src/lib.rs     | 35 +++++++++++++++++++
 .../src/splitter/common.rs                    |  3 +-
 .../src/splitter/dml.rs                       | 31 ++++++++++++++++
 3 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/crates/pgls_statement_splitter/src/lib.rs b/crates/pgls_statement_splitter/src/lib.rs
index 6f1ba02d0..3c8329956 100644
--- a/crates/pgls_statement_splitter/src/lib.rs
+++ b/crates/pgls_statement_splitter/src/lib.rs
@@ -241,6 +241,41 @@ END;",
         }
     }
 
+    #[test]
+    fn explain() {
+        let stmts = vec![
+            "EXPLAIN SELECT 1;",
+            "EXPLAIN ANALYZE SELECT 1;",
+            "EXPLAIN ANALYSE SELECT 1;",
+            "EXPLAIN VERBOSE SELECT 1;",
+            "EXPLAIN ANALYZE VERBOSE SELECT 1;",
+            "EXPLAIN (ANALYZE, BUFFERS) SELECT * FROM my_table;",
+            "EXPLAIN (FORMAT JSON) SELECT * FROM my_table WHERE id = 1;",
+            "EXPLAIN INSERT INTO my_table (id) VALUES (1);",
+            "EXPLAIN ANALYZE UPDATE my_table SET col = 1 WHERE id = 2;",
+            "EXPLAIN DELETE FROM my_table WHERE id = 1;",
+            "EXPLAIN WITH cte AS (SELECT 1 AS x) SELECT * FROM cte;",
+            "EXPLAIN CREATE TABLE my_copy AS SELECT * FROM my_table;",
+            "explain analyze select 1;",
+        ];
+
+        for stmt in stmts {
+            Tester::from(stmt).expect_statements(vec![stmt]);
+        }
+    }
+
+    #[test]
+    fn explain_between_statements() {
+        Tester::from("EXPLAIN SELECT 1;\nSELECT 2;")
+            .expect_statements(vec!["EXPLAIN SELECT 1;", "SELECT 2;"]);
+
+        Tester::from("explain select 1\n\nselect 2")
+            .expect_statements(vec!["explain select 1", "select 2"]);
+
+        Tester::from("explain select 1\nselect 2")
+            .expect_statements(vec!["explain select 1", "select 2"]);
+    }
+
     #[test]
     fn revoke() {
         Tester::from("revoke delete on table \"public\".\"voice_call\" from \"anon\";")
diff --git a/crates/pgls_statement_splitter/src/splitter/common.rs b/crates/pgls_statement_splitter/src/splitter/common.rs
index df8b09760..21619d75c 100644
--- a/crates/pgls_statement_splitter/src/splitter/common.rs
+++ b/crates/pgls_statement_splitter/src/splitter/common.rs
@@ -7,7 +7,7 @@ use super::{
     Splitter,
     data::at_statement_start,
     ddl::{alter, create},
-    dml::{cte, delete, insert, select, update},
+    dml::{cte, delete, explain, insert, select, update},
 };
 
 #[derive(Debug)]
@@ -58,6 +58,7 @@ pub(crate) fn statement(p: &mut Splitter) -> SplitterResult {
         SyntaxKind::DELETE_KW => delete(p),
         SyntaxKind::CREATE_KW => create(p),
         SyntaxKind::ALTER_KW => alter(p),
+        SyntaxKind::EXPLAIN_KW => explain(p),
         _ => unknown(p, &[]),
     };
 
diff --git a/crates/pgls_statement_splitter/src/splitter/dml.rs b/crates/pgls_statement_splitter/src/splitter/dml.rs
index 9af68593a..f48811b20 100644
--- a/crates/pgls_statement_splitter/src/splitter/dml.rs
+++ b/crates/pgls_statement_splitter/src/splitter/dml.rs
@@ -5,6 +5,7 @@ use crate::splitter::common::SplitterResult;
 use super::{
     Splitter,
     common::{parenthesis, unknown},
+    ddl::create,
 };
 
 pub(crate) fn cte(p: &mut Splitter) -> SplitterResult {
@@ -64,3 +65,33 @@ pub(crate) fn delete(p: &mut Splitter) -> SplitterResult {
 
     unknown(p, &[])
 }
+
+/// `EXPLAIN [ ANALYZE ] [ VERBOSE ] statement` and
+/// `EXPLAIN ( option [, ...] ) statement`
+///
+/// The explained statement must not be treated as the start of a new
+/// statement, so we consume the EXPLAIN prefix and delegate to the splitter
+/// function of the wrapped statement.
+pub(crate) fn explain(p: &mut Splitter) -> SplitterResult {
+    p.expect(SyntaxKind::EXPLAIN_KW)?;
+
+    p.eat(SyntaxKind::ANALYZE_KW)?;
+    p.eat(SyntaxKind::ANALYSE_KW)?;
+    p.eat(SyntaxKind::VERBOSE_KW)?;
+
+    if p.current() == SyntaxKind::L_PAREN {
+        parenthesis(p)?;
+    }
+
+    match p.current() {
+        SyntaxKind::WITH_KW => cte(p),
+        SyntaxKind::SELECT_KW => select(p),
+        SyntaxKind::INSERT_KW => insert(p),
+        SyntaxKind::UPDATE_KW => update(p),
+        SyntaxKind::DELETE_KW => delete(p),
+        // EXPLAIN CREATE TABLE ... AS / CREATE MATERIALIZED VIEW ... AS
+        SyntaxKind::CREATE_KW => create(p),
+        // VALUES, EXECUTE, DECLARE, MERGE
+        _ => unknown(p, &[]),
+    }
+}