perf: mark eql_v2.like / eql_v2.ilike IMMUTABLE

src/operators/~~.sql

@@ -10,6 +10,9 @@
 --! Uses bloom filter index terms to test substring containment without decryption.
 --! Requires 'match' index configuration on the column.
 --!
+--! Marked IMMUTABLE so the planner inlines the body and a functional index on
+--! `eql_v2.bloom_filter(col)` can match `WHERE eql_v2.like(col, val)`.
+--!
 --! @param a eql_v2_encrypted Haystack (value to search in)
 --! @param b eql_v2_encrypted Needle (pattern to search for)
 --! @return Boolean True if bloom filter of a contains bloom filter of b
@@ -19,9 +22,11 @@
 --! @see eql_v2.add_search_config
 CREATE FUNCTION eql_v2.like(a eql_v2_encrypted, b eql_v2_encrypted)
 RETURNS boolean
+LANGUAGE SQL
+IMMUTABLE STRICT PARALLEL SAFE
 AS $$
   SELECT eql_v2.bloom_filter(a) @> eql_v2.bloom_filter(b);
-$$ LANGUAGE SQL;
+$$;
 
 --! @brief Case-insensitive pattern matching helper
 --! @internal
@@ -39,9 +44,11 @@ $$ LANGUAGE SQL;
 --! @see eql_v2.add_search_config
 CREATE FUNCTION eql_v2.ilike(a eql_v2_encrypted, b eql_v2_encrypted)
 RETURNS boolean
+LANGUAGE SQL
+IMMUTABLE STRICT PARALLEL SAFE
 AS $$
   SELECT eql_v2.bloom_filter(a) @> eql_v2.bloom_filter(b);
-$$ LANGUAGE SQL;
+$$;
 
 --! @brief LIKE operator for encrypted values (pattern matching)
 --!

tests/sqlx/tests/like_operator_tests.rs

@@ -160,3 +160,39 @@ async fn ilike_operator_case_insensitive_matches(pool: PgPool) -> Result<()> {
 
     Ok(())
 }
+
+/// Regression test for issue #189: eql_v2.like / eql_v2.ilike must be IMMUTABLE
+/// so the planner inlines them and a functional bloom_filter index can match
+/// `WHERE eql_v2.like(col, val)`. Without this, queries silently seq-scan.
+#[sqlx::test]
+async fn like_and_ilike_are_immutable(pool: PgPool) -> Result<()> {
+    let sql = "SELECT proname, provolatile::text \
+               FROM pg_proc \
+               WHERE pronamespace = 'eql_v2'::regnamespace \
+                 AND proname IN ('like', 'ilike') \
+                 AND pronargs = 2 \
+               ORDER BY proname";
+
+    let rows = sqlx::query(sql)
+        .fetch_all(&pool)
+        .await
+        .context("querying pg_proc for like/ilike volatility")?;
+
+    assert_eq!(
+        rows.len(),
+        2,
+        "expected eql_v2.like and eql_v2.ilike to exist"
+    );
+
+    for row in rows {
+        let name: String = row.try_get("proname")?;
+        let volatility: String = row.try_get("provolatile")?;
+        assert_eq!(
+            volatility, "i",
+            "eql_v2.{} must be IMMUTABLE (provolatile='i') for index inlining; got '{}'",
+            name, volatility,
+        );
+    }
+
+    Ok(())
+}