Basic GTID tracking.

[dveeden]

https://rt.cpan.org/Public/Bug/Display.html?id=119122
https://dev.mysql.com/doc/refman/5.7/en/mysql-session-track-get-first.html

This code is only tested at a very basic level.

• The test runs, but other tests fail on a GTID enabled server. For example:

t/53comment.t ........................... DBD::mysql::db do failed: Statement violates GTID consistency: CREATE TEMPORARY TABLE and DROP TEMPORARY TABLE can only be executed outside transactional context.  These statements are also not allowed in a function or trigger because functions and triggers are also considered to be multi-statement transactions. at t/53comment.t line 32.

• This is specific for GTID tracking and doesn't to schema/state/variable tracking. This could be made in a more generic feature, but currently I think this more specific feature makes sense.
• This is tested against 5.7 and it should be possible to compile it against 5.6 and below (with loss of function)
• I did not test against MariaDB server
• I did not test compilation against MariaDB libraries
• It probably works against MariaDB: https://jira.mariadb.org/browse/MDEV-8931
• MariaDB has a different GTID implementation, so it might behave differently (e.g. test might fail because the MariaDB implementation has a shorter GTID)
• The test only runs against a server were this is enabled in the config, so this gets very limited testing. Unfortunately this can't be enabled dynamically, so we can't enable it during the test.

Example:

#!/usr/bin/perl
use v5.24.0;
use DBI;

my $dbh = DBI->connect("DBI:mysql:database=test;mysql_socket=/tmp/mysql_sandbox5717.sock",
                       "msandbox", "msandbox",
                       {'RaiseError' => 1});

$dbh->do('FLUSH PRIVILEGES');
say "GTID= $dbh->{'mysql_gtids'}";

$dbh->disconnect();

[mbeijen]

Hi Daniël, thanks for the pull request.
I found this also does not compile against mysql-connector-c version 6.1.6 which are 5.6 libraries;

dbdimp.c:2859:58: error: use of undeclared identifier 'SESSION_TRACK_GTIDS'; did you mean 'SESSION_TRACK_SCHEMA'?
      if (mysql_session_track_get_first(imp_dbh->pmysql, SESSION_TRACK_GTIDS, &data, &length) == 0)
                                                         ^~~~~~~~~~~~~~~~~~~
                                                         SESSION_TRACK_SCHEMA

Maybe it is better to depend on if SESSION_TRACK_GTIDS is defined than to define on the version number.

[dveeden]

I used the version number from https://dev.mysql.com/doc/refman/5.7/en/mysql-session-track-get-first.html which is for the function, but not for SESSION_TRACK_GTIDS. I've now fixed the version number.

Note that Connector/C 6.1.6 is not 5.6, but 5.7..

$ rpm -qf /usr/include/mysql/mysql_com.h
mysql-connector-c-devel-6.1.6-1.el7.i686

$ grep -w MYSQL_VERSION_ID /usr/include/mysql/mysql_version.h 
#define MYSQL_VERSION_ID            50706

Changing this to check if SESSION_TRACK_GTIDS is defined might indeed be a better option.

[pali]

Hi! Please rebase your patches on top of master branch. Travis CI is now configured to test DBD::mysql with different MySQL & MariaDB versions.

[pali]

So... it does not compile with MariaDB client.

[pali]

If this feature is not supported by MariaDB client, then rather check that MARIADB_BASE_VERSION is not defined.

In future Oracle can decide that MySQL version could be increased to 10 or 11 and this code stop working.

[CaptTofu]

can we move this along? Any objections?

[dveeden]

What needs to be done to get this merged?

[dveeden]

This might be a slightly better example:

#!/usr/bin/perl
use v5.24.0;
use DBI;

my $master_dbh = DBI->connect("DBI:mysql:database=test;host=mymaster", "myuser", "mypass");
my $slave_dbh = DBI->connect("DBI:mysql:database=test;host=myslave1", "myuser", "mypass");

# Write to the master
$master_dbh->do('SET SESSION session_track_gtids=OWN_GTID');
$master_dbh->do("INSERT INTO t1() VALUES()");
my $gtid = $master_dbh->{'mysql_gtids'};
$master_dbh->disconnect();
say "GTID= $gtid";

# Wait until the GTID hits the slave (or timeout)
my $sth = $slave_dbh->prepare("SELECT WAIT_FOR_EXECUTED_GTID_SET(?, 10)");
$sth->execute($gtid);
if ($sth->fetchrow_arrayref()->[0] != 0) {
  say "Got timeout";
}
$sth->finish();
$slave_dbh->disconnect();

[CaptTofu]

I merged this this morning - time to get a release going.