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d039346a7a
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>
135 lines
3.3 KiB
Text
135 lines
3.3 KiB
Text
SET GLOBAL binlog_gtid_index= 0;
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SET GLOBAL binlog_gtid_index= 1;
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SET @gtid1= @@gtid_binlog_pos;
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CREATE TABLE t1 (a INT PRIMARY KEY);
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SET @gtid2= @@gtid_binlog_pos;
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INSERT INTO t1 VALUES (1);
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SET @gtid3= @@gtid_binlog_pos;
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INSERT INTO t1 VALUES (2);
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INSERT INTO t1 VALUES (3);
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INSERT INTO t1 VALUES (4);
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SET @gtid4= @@gtid_binlog_pos;
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INSERT INTO t1 VALUES (5);
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SET @gtid5= @@gtid_binlog_pos;
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SET @gtid6= @@gtid_binlog_pos;
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INSERT INTO t1 VALUES (106);
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INSERT INTO t1 VALUES (107);
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Ok
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1
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Ok
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1
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Ok
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1
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Ok
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1
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Ok
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1
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Ok
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1
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FLUSH BINARY LOGS;
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Ok
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1
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Ok
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1
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Ok
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1
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Ok
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1
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Ok
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1
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Ok
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1
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*** Test that purge deletes the gtid index files. ***
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FLUSH BINARY LOGS;
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INSERT INTO t1 VALUES (200);
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FLUSH BINARY LOGS;
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INSERT INTO t1 VALUES (201);
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FLUSH BINARY LOGS;
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INSERT INTO t1 VALUES (202);
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PURGE BINARY LOGS TO 'FILE';
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*** Test missed index lookup due to missing or corrupt index file.
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FLUSH NO_WRITE_TO_BINLOG BINARY LOGS;
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INSERT INTO t1 VALUES (301);
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INSERT INTO t1 VALUES (302);
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INSERT INTO t1 VALUES (303);
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SET @gtid_pos= @@GLOBAL.gtid_binlog_pos;
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INSERT INTO t1 VALUES (304);
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INSERT INTO t1 VALUES (305);
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FLUSH NO_WRITE_TO_BINLOG STATUS;
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+++ Initial status:
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SHOW STATUS LIKE 'binlog_gtid_index_%';
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Variable_name Value
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Binlog_gtid_index_hit 0
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Binlog_gtid_index_miss 0
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+++ GTID Lookup in good index.
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Gtid_Lookup_Ok
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1
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SHOW STATUS LIKE 'binlog_gtid_index_%';
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Variable_name Value
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Binlog_gtid_index_hit 1
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Binlog_gtid_index_miss 0
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+++ GTID Lookup, index file is missing.
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Gtid_Lookup_Ok
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1
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SHOW STATUS LIKE 'binlog_gtid_index_%';
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Variable_name Value
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Binlog_gtid_index_hit 1
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Binlog_gtid_index_miss 1
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FLUSH NO_WRITE_TO_BINLOG BINARY LOGS;
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INSERT INTO t1 VALUES (306);
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SET @gtid_pos= @@GLOBAL.gtid_binlog_pos;
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INSERT INTO t1 VALUES (307);
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INSERT INTO t1 VALUES (308);
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FLUSH NO_WRITE_TO_BINLOG BINARY LOGS;
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+++ GTID Lookup, first page of index is corrupt.
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Gtid_Lookup_Ok
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1
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SHOW STATUS LIKE 'binlog_gtid_index_%';
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Variable_name Value
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Binlog_gtid_index_hit 1
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Binlog_gtid_index_miss 2
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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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SET GLOBAL binlog_gtid_index_page_size= 64;
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SET GLOBAL binlog_gtid_index_span_min= 1;
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FLUSH NO_WRITE_TO_BINLOG BINARY LOGS;
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INSERT INTO t1 VALUES (310);
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INSERT INTO t1 VALUES (311);
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INSERT INTO t1 VALUES (312);
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SET @gtid_pos= @@GLOBAL.gtid_binlog_pos;
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INSERT INTO t1 VALUES (313);
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INSERT INTO t1 VALUES (314);
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INSERT INTO t1 VALUES (315);
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INSERT INTO t1 VALUES (316);
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FLUSH NO_WRITE_TO_BINLOG BINARY LOGS;
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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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+++ GTID Lookup, root page of index is corrupt.
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Gtid_Lookup_Ok
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1
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SHOW STATUS LIKE 'binlog_gtid_index_%';
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Variable_name Value
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Binlog_gtid_index_hit 1
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Binlog_gtid_index_miss 3
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*** Test BINLOG_GTID_POS() with too-large offset.
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FLUSH NO_WRITE_TO_BINLOG BINARY LOGS;
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INSERT INTO t1 VALUES (401);
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INSERT INTO t1 VALUES (402);
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+++ Test the hot index.
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SELECT BINLOG_GTID_POS('FILE', 100000000);
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BINLOG_GTID_POS('FILE', 100000000)
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NULL
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SHOW STATUS LIKE 'binlog_gtid_index_%';
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Variable_name Value
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Binlog_gtid_index_hit 2
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Binlog_gtid_index_miss 3
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FLUSH NO_WRITE_TO_BINLOG BINARY LOGS;
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+++ Test the cold index.
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SELECT BINLOG_GTID_POS('FILE', 100000000);
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BINLOG_GTID_POS('FILE', 100000000)
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NULL
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SHOW STATUS LIKE 'binlog_gtid_index_%';
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Variable_name Value
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Binlog_gtid_index_hit 3
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Binlog_gtid_index_miss 3
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DROP TABLE t1;
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