From a464b453f3ee5d89147c57349f5b1dfffa2c2153 Mon Sep 17 00:00:00 2001
From: Vaibhav Kushwaha <34186745+vaibhav-yb@users.noreply.github.com>
Date: Tue, 12 Nov 2024 15:49:31 +0530
Subject: [PATCH] [DBZ-PGYB] Set transaction isolation level before executing
 snapshot query (#164)

This PR makes the changes to set the transaction isolation level to
`SERIALIZABLE, READ ONLY, DEFERRABLE` before executing the snapshot read
query.
---
 .../postgresql/PostgresSnapshotChangeEventSource.java       | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/debezium-connector-postgres/src/main/java/io/debezium/connector/postgresql/PostgresSnapshotChangeEventSource.java b/debezium-connector-postgres/src/main/java/io/debezium/connector/postgresql/PostgresSnapshotChangeEventSource.java
index ed247de8cbe..fc0924cf37d 100644
--- a/debezium-connector-postgres/src/main/java/io/debezium/connector/postgresql/PostgresSnapshotChangeEventSource.java
+++ b/debezium-connector-postgres/src/main/java/io/debezium/connector/postgresql/PostgresSnapshotChangeEventSource.java
@@ -293,6 +293,12 @@ protected void setSnapshotTransactionIsolationLevel(boolean isOnDemand) throws S
         } else {
             LOGGER.info("Skipping setting snapshot time, snapshot data will not be consistent");
         }
+
+        // Regardless of whether consistent snapshot is enabled or not, we need to set the
+        // transaction isolation level.
+        String transactionIsolationLevelStatement = "SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL SERIALIZABLE, READ ONLY, DEFERRABLE;";
+        LOGGER.info("Setting transaction isolation levels with statement {}", transactionIsolationLevelStatement);
+        jdbcConnection.executeWithoutCommitting(transactionIsolationLevelStatement);
     }
 
     /**