alexey.rassokhin/tet123
1
0
Fork 0
Code Issues Pull Requests 1 Packages Projects Releases Wiki Activity

DBZ-210 Lock tables before starting tx in snapshot

Browse Source
This commit is contained in:
Jiri Pechanec 2017-08-29 07:15:08 +02:00 committed by Gunnar Morling
parent 01980cf29b
commit 7b9c29efe6
1 changed files with 17 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
debezium-connector-mysql/src/main/java/io/debezium/connector/mysql/SnapshotReader.java
View File

@ -172,37 +172,40 @@ protected void execute() {
int step = 1;
try {
// ------
// STEP 1
// ------
// First, start a transaction and request that a consistent MVCC snapshot is obtained immediately.
// See http://dev.mysql.com/doc/refman/5.7/en/commit.html
if (!isRunning()) return;
logger.info("Step 1: start transaction with consistent snapshot");
sql.set("START TRANSACTION WITH CONSISTENT SNAPSHOT");
mysql.execute(sql.get());
isTxnStarted = true;
// ------------------------------------
// LOCK TABLES and READ BINLOG POSITION
// LOCK TABLES
// ------------------------------------
// Obtain read lock on all tables. This statement closes all open tables and locks all tables
// for all databases with a global read lock, and it prevents ALL updates while we have this lock.
// It also ensures that everything we do while we have this lock will be consistent.
if (!isRunning()) return;
try {
logger.info("Step 2: flush and obtain global read lock to prevent writes to database");
logger.info("Step 1: flush and obtain global read lock to prevent writes to database");
sql.set("FLUSH TABLES WITH READ LOCK");
mysql.execute(sql.get());
lockAcquired = clock.currentTimeInMillis();
metrics.globalLockAcquired();
isLocked = true;
} catch (SQLException e) {
logger.info("Step 2: unable to flush and acquire global read lock, will use table read locks after reading table names");
logger.info("Step 1: unable to flush and acquire global read lock, will use table read locks after reading table names");
// Continue anyway, since RDS (among others) don't allow setting a global lock
assert !isLocked;
}
// ------
// START TRANSACTION
// ------
// First, start a transaction and request that a consistent MVCC snapshot is obtained immediately.
// See http://dev.mysql.com/doc/refman/5.7/en/commit.html
if (!isRunning()) return;
logger.info("Step 2: start transaction with consistent snapshot");
sql.set("START TRANSACTION WITH CONSISTENT SNAPSHOT");
mysql.execute(sql.get());
isTxnStarted = true;
// ------------------------------------
// READ BINLOG POSITION
// ------------------------------------
if (!isRunning()) return;
step = 3;
if (isLocked) {