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[SPARK-57446][SQL] Apply escapeSql to comment in JDBC table/schema comment queries #56506

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[SPARK-57446][SQL] Apply escapeSql to comment in JDBC table/schema comment queries #56506

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4 changes: 2 additions & 2 deletions sql/core/src/main/scala/org/apache/spark/sql/jdbc/JdbcDialects.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -716,11 +716,11 @@ abstract class JdbcDialect extends Serializable with Logging {
}

def getTableCommentQuery(table: String, comment: String): String = {
s"COMMENT ON TABLE $table IS '$comment'"
s"COMMENT ON TABLE $table IS '${escapeSql(comment)}'"
}

def getSchemaCommentQuery(schema: String, comment: String): String = {
s"COMMENT ON SCHEMA ${quoteIdentifier(schema)} IS '$comment'"
s"COMMENT ON SCHEMA ${quoteIdentifier(schema)} IS '${escapeSql(comment)}'"
}

def removeSchemaCommentQuery(schema: String): String = {
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2 changes: 1 addition & 1 deletion sql/core/src/main/scala/org/apache/spark/sql/jdbc/MySQLDialect.scala
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Expand Up @@ -266,7 +266,7 @@ private case class MySQLDialect() extends JdbcDialect with SQLConfHelper with No

// See https://dev.mysql.com/doc/refman/8.0/en/alter-table.html
override def getTableCommentQuery(table: String, comment: String): String = {
s"ALTER TABLE $table COMMENT = '$comment'"
s"ALTER TABLE $table COMMENT = '${escapeSql(comment)}'"

@cloud-fan cloud-fan Jun 15, 2026

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Non-blocking, out of scope — just flagging for completeness: escapeSql doubles ' but doesn't escape \. MySQL treats backslash as an escape character by default (NO_BACKSLASH_ESCAPES unset), so a comment containing a backslash can still be mangled (or break the statement if trailing) here. This is pre-existing and shared with compileValue's MySQL string-predicate handling, and this PR is a strict improvement for the single-quote case, so nothing to change here.

}

override def getJDBCType(dt: DataType): Option[JdbcType] = dt match {
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13 changes: 13 additions & 0 deletions sql/core/src/test/scala/org/apache/spark/sql/jdbc/JDBCSuite.scala
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Expand Up @@ -943,6 +943,19 @@ class JDBCSuite extends SharedSparkSession {
assert(mySQLSQL(StringStartsWith("c", "a%b_")) === """`c` LIKE 'a\\%b\\_%' ESCAPE '\\'""")
}

test("SPARK-57446: escape single quotes in JDBC comment queries") {
val defaultDialect = JdbcDialects.get("jdbc:")
assert(defaultDialect.getTableCommentQuery("t", "a'b") ===
"COMMENT ON TABLE t IS 'a''b'")
assert(defaultDialect.getSchemaCommentQuery("s", "a'b") ===
"""COMMENT ON SCHEMA "s" IS 'a''b'""")

// MySQL overrides getTableCommentQuery with its own ALTER TABLE syntax.
val mySQLDialect = JdbcDialects.get("jdbc:mysql://127.0.0.1/db")
assert(mySQLDialect.getTableCommentQuery("t", "a'b") ===
"ALTER TABLE t COMMENT = 'a''b'")
}

test("Dialect unregister") {
JdbcDialects.unregisterDialect(H2Dialect())
try {
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