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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>
89 lines
2.6 KiB
Text
89 lines
2.6 KiB
Text
--source include/have_sequence.inc
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--source include/have_innodb.inc
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--source include/master-slave.inc
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--source include/have_binlog_format_mixed.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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--source include/start_slave.inc
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--connection master
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CREATE TABLE t1 (a INT PRIMARY KEY, b INT) ENGINE=InnoDB;
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INSERT INTO t1 VALUES (0, 0);
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--echo *** Test looking up a lot of different event positions and GTIDs.
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# A function for comparing GTID positions.
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# Handles that the domain_id order is different in the two strings.
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# Works by repeatedly removing one GTID from each string. If the strings have
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# the same length and nothing is left at the end, then they are identical.
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delimiter //;
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CREATE FUNCTION gtid_eq(a VARCHAR(255), b VARCHAR(255)) RETURNS BOOLEAN DETERMINISTIC
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BEGIN
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DECLARE g VARCHAR(255);
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IF a IS NULL OR b IS NULL OR LENGTH(a) != LENGTH(b) THEN
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RETURN FALSE;
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END IF;
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SET a= CONCAT(a, ',');
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SET b= CONCAT(',', b, ',');
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WHILE LENGTH(a) > 0 DO
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SET g= REGEXP_SUBSTR(a, '^[^,]+,');
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SET a= SUBSTRING(a, LENGTH(g)+1);
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SET b= REPLACE(b, CONCAT(',', g), ',');
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END WHILE;
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RETURN b = ',';
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END //
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delimiter ;//
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SET @old_page_size= @@GLOBAL.binlog_gtid_index_page_size;
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SET @old_span_min= @@GLOBAL.binlog_gtid_index_span_min;
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--echo *** A fair amount of work with default GTID index settings.
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--let $NUM_POS= 200
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--let $NUM_DOMAIN= 5
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--let $NUM_SERVER= 5
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--let $NUM_SLAVE_CONNECTS= 50
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--let $RND_SEED= 42
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--source suite/rpl/include/rpl_gtid_index.inc
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--echo *** A lot of GTIDs with small btree pages to stress the Btree code.
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--let $NUM_POS= 1000
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--let $NUM_DOMAIN= 10
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--let $RND_SEED= 150
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SET GLOBAL binlog_gtid_index_page_size= 64;
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SET GLOBAL binlog_gtid_index_span_min= 1;
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--source suite/rpl/include/rpl_gtid_index.inc
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--echo *** Small page size with sparse index.
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--let $NUM_POS= 200
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--let $RND_SEED= 666
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SET GLOBAL binlog_gtid_index_page_size= 64;
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SET GLOBAL binlog_gtid_index_span_min= 2048;
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--source suite/rpl/include/rpl_gtid_index.inc
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--echo *** Medium page size.
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--let $NUM_POS= 200
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--let $RND_SEED= 1024
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SET GLOBAL binlog_gtid_index_page_size= 512;
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SET GLOBAL binlog_gtid_index_span_min= 512;
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--source suite/rpl/include/rpl_gtid_index.inc
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--echo *** Large page size.
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--let $NUM_POS= 200
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--let $RND_SEED= 12345
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SET GLOBAL binlog_gtid_index_page_size= 16384;
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SET GLOBAL binlog_gtid_index_span_min= 1;
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--source suite/rpl/include/rpl_gtid_index.inc
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# Cleanup.
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--connection master
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SET GLOBAL binlog_gtid_index_page_size= @old_page_size;
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SET GLOBAL binlog_gtid_index_span_min= @old_span_min;
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DROP TABLE t1;
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DROP FUNCTION gtid_eq;
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--source include/rpl_end.inc
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