From 0b6edbe865c7d05b0c9922d308953f3f20b8b443 Mon Sep 17 00:00:00 2001
From: Mohammad Tafzeel Shams <tafzeel.shams@mariadb.com>
Date: Tue, 23 Jun 2026 15:26:01 +0530
Subject: [PATCH] MDEV-26123: Always mark spatial index reads as locking

A SELECT query could fail with ER_READ_ONLY_TRANSACTION when search
on spatial index is done after search on non-spatial index.

R-tree index search always require page locks. Previously,
trx->will_lock was only set for spatial indexes when the transaction
had not yet been started. If a transaction was already active due to
a prior non-spatial index access, index_read() for spatial index
returned HA_ERR_READ_ONLY_TRANSACTION instead of marking the transaction
as locking.

Fix:
- ha_innobase::index_read() : Set trx->will_lock unconditionally for
spatial index, ensuring that R-tree searches can acquire the required
page locks regardless of transaction state.
---
 .../suite/innodb_gis/r/rtree_search.result    | 36 ++++++++++++++++
 .../suite/innodb_gis/t/rtree_search.test      | 42 +++++++++++++++++++
 storage/innobase/handler/ha_innodb.cc         |  8 +---
 3 files changed, 80 insertions(+), 6 deletions(-)

diff --git a/mysql-test/suite/innodb_gis/r/rtree_search.result b/mysql-test/suite/innodb_gis/r/rtree_search.result
index d8a8d209cd36a..e6ca3c3533727 100644
--- a/mysql-test/suite/innodb_gis/r/rtree_search.result
+++ b/mysql-test/suite/innodb_gis/r/rtree_search.result
@@ -250,3 +250,39 @@ count(*)
 drop procedure curdemo;
 drop table t3;
 drop table t1;
+#
+# MDEV 26123 : Always mark spatial index reads as locking
+#
+SET @old_autocommit = @@autocommit;
+SET @old_tx_read_only = @@session.tx_read_only;
+CREATE TABLE t1 (
+c1 INT PRIMARY KEY,
+category INT NOT NULL,
+p POINT NOT NULL,
+KEY idx_category (category),
+SPATIAL INDEX sp_idx_p (p)
+) ENGINE=InnoDB;
+INSERT INTO t1 VALUES
+(1, 10, POINT(1,2));
+CREATE PROCEDURE populate_t1()
+BEGIN
+DECLARE i INT DEFAULT 2;
+WHILE i <= 5000 DO
+INSERT INTO t1 VALUES
+(i, 20, POINT(5,5));
+SET i = i + 1;
+END WHILE;
+END |
+CALL populate_t1();
+SELECT COUNT(*) FROM t1 WHERE ST_Contains(t1.p, (SELECT p FROM t1 WHERE category = 10));
+COUNT(*)
+1
+SET SESSION TRANSACTION READ ONLY;
+SET autocommit = OFF;
+SELECT COUNT(*) FROM t1 WHERE category = (SELECT category FROM t1 WHERE ST_EQUALS(p, POINT(1,2)));
+COUNT(*)
+1
+SET autocommit = @old_autocommit;
+SET SESSION tx_read_only = @old_tx_read_only;
+DROP PROCEDURE populate_t1;
+DROP TABLE t1;
diff --git a/mysql-test/suite/innodb_gis/t/rtree_search.test b/mysql-test/suite/innodb_gis/t/rtree_search.test
index 6bbd84a25cf0e..290b6634825a1 100644
--- a/mysql-test/suite/innodb_gis/t/rtree_search.test
+++ b/mysql-test/suite/innodb_gis/t/rtree_search.test
@@ -139,3 +139,45 @@ drop procedure curdemo;
 drop table t3;
 drop table t1;
 
+--echo #
+--echo # MDEV 26123 : Always mark spatial index reads as locking
+--echo #
+SET @old_autocommit = @@autocommit;
+SET @old_tx_read_only = @@session.tx_read_only;
+
+CREATE TABLE t1 (
+    c1 INT PRIMARY KEY,
+    category INT NOT NULL,
+    p POINT NOT NULL,
+    KEY idx_category (category),
+    SPATIAL INDEX sp_idx_p (p)
+) ENGINE=InnoDB;
+
+INSERT INTO t1 VALUES
+(1, 10, POINT(1,2));
+
+DELIMITER |;
+CREATE PROCEDURE populate_t1()
+BEGIN
+    DECLARE i INT DEFAULT 2;
+
+    WHILE i <= 5000 DO
+        INSERT INTO t1 VALUES
+            (i, 20, POINT(5,5));
+        SET i = i + 1;
+    END WHILE;
+END |
+DELIMITER ;|
+CALL populate_t1();
+
+SELECT COUNT(*) FROM t1 WHERE ST_Contains(t1.p, (SELECT p FROM t1 WHERE category = 10));
+
+SET SESSION TRANSACTION READ ONLY;
+SET autocommit = OFF;
+SELECT COUNT(*) FROM t1 WHERE category = (SELECT category FROM t1 WHERE ST_EQUALS(p, POINT(1,2)));
+
+# Cleanup
+SET autocommit = @old_autocommit;
+SET SESSION tx_read_only = @old_tx_read_only;
+DROP PROCEDURE populate_t1;
+DROP TABLE t1;
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index 02649112b8cd2..2ddcb8c93ff60 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -9012,12 +9012,8 @@ ha_innobase::index_read(
 
 	/* For R-Tree index, we will always place the page lock to
 	pages being searched */
-	if (index->is_spatial() && !m_prebuilt->trx->will_lock) {
-		if (trx_state != TRX_STATE_NOT_STARTED) {
-			DBUG_RETURN(HA_ERR_READ_ONLY_TRANSACTION);
-		} else {
-			m_prebuilt->trx->will_lock = true;
-		}
+	if (index->is_spatial()) {
+		m_prebuilt->trx->will_lock = true;
 	}
 
 	/* Note that if the index for which the search template is built is not