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Improve the performance of slave connect using B+-Tree indexes on each binlog file. The index allows fast lookup of a GTID position to the corresponding offset in the binlog file, as well as lookup of a position to find the corresponding GTID position. This eliminates a costly sequential scan of the starting binlog file to find the GTID starting position when a slave connects. This is especially costly if the binlog file is not cached in memory (IO cost), or if it is encrypted or a lot of slaves connect simultaneously (CPU cost). The size of the index files is generally less than 1% of the binlog data, so not expected to be an issue. Most of the work writing the index is done as a background task, in the binlog background thread. This minimises the performance impact on transaction commit. A simple global mutex is used to protect index reads and (background) index writes; this is fine as slave connect is a relatively infrequent operation. Here are the user-visible options and status variables. The feature is on by default and is expected to need no tuning or configuration for most users. binlog_gtid_index On by default. Can be used to disable the indexes for testing purposes. binlog_gtid_index_page_size (default 4096) Page size to use for the binlog GTID index. This is the size of the nodes in the B+-tree used internally in the index. A very small page-size (64 is the minimum) will be less efficient, but can be used to stress the BTree-code during testing. binlog_gtid_index_span_min (default 65536) Control sparseness of the binlog GTID index. If set to N, at most one index record will be added for every N bytes of binlog file written. This can be used to reduce the number of records in the index, at the cost only of having to scan a few more events in the binlog file before finding the target position Two status variables are available to monitor the use of the GTID indexes: Binlog_gtid_index_hit Binlog_gtid_index_miss The "hit" status increments for each successful lookup in a GTID index. The "miss" increments when a lookup is not possible. This indicates that the index file is missing (eg. binlog written by old server version without GTID index support), or corrupt. Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>
74 lines
2.1 KiB
Plaintext
74 lines
2.1 KiB
Plaintext
#
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# Purpose:
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# If a fake Glle event follows a Gtid event, we need to ensure the rest of
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# the group should not terminate at the Glle event. MDEV-28550 revealed that
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# a Glle would terminate the event and upon reconnect, the DDL would be lost.
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#
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# Methodology:
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# Force the primary to send a fake GLLE event after a GTID on a "reconnect"
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# and ensure that both 1) the replica does not error, and 2) the original
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# command within the GTID is executed.
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#
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# References:
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# MDEV-28550: improper handling of replication event group that contains Gtid_log_list_event
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--source include/master-slave.inc
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# Independent of binlog format
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--source include/have_binlog_format_statement.inc
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--connection slave
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--source include/stop_slave.inc
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CHANGE MASTER TO MASTER_USE_GTID=slave_pos;
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--echo #
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--echo # Initialize test data
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--connection master
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--source include/wait_for_binlog_checkpoint.inc
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create table t1 (a int);
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SET @@session.server_id= 3;
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create table t2 (a int);
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--source include/save_master_gtid.inc
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--echo #
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--echo # Have the replica "reconnect" and the primary will send Gtid, Glle, DDL
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--connection slave
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eval set global gtid_slave_pos="0-3-1";
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--source include/start_slave.inc
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--source include/sync_with_master_gtid.inc
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--echo #
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--echo # Ensure that the replica did not error
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connection slave;
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--source include/sync_with_master_gtid.inc
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let $error= query_get_value(SHOW SLAVE STATUS, Last_SQL_Error, 1);
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--echo Last_SQL_Error = $error
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let $errno= query_get_value(SHOW SLAVE STATUS, Last_SQL_Errno, 1);
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--echo Last_SQL_Errno = $errno
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--echo #
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--echo # Ensure that the primary sent a Glle after a Gtid event
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let $binlog_file= query_get_value(SHOW SLAVE STATUS, Relay_Log_File, 1);
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let $binlog_start= $relaylog_start;
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let $binlog_limit=0,10;
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--source include/show_relaylog_events.inc
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--echo #
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--echo # Ensure the DDL was executed on the replica
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if (!`SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = 'test' AND table_name = 't2'`)
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{
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die "t2 should exist on slave";
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}
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--echo #
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--echo # Cleanup
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--echo # t1 does not make it to the replica
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--connection master
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set sql_log_bin=0;
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DROP TABLE t1;
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set sql_log_bin=1;
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DROP TABLE t2;
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--source include/rpl_end.inc
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