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The rollback of the modification of a pre-existing record should involve a purge-like operation. Before MDEV-12288 the only purge-like operation was the removal of a delete-marked record. After MDEV-12288, any rollback of updating an existing record must reset the DB_TRX_ID column when it is no longer visible in the purge read view. row_vers_must_preserve_del_marked(): Remove. It is cleaner to perform the check directly in row0umod.cc. row_trx_id_offset(): Auxiliary function to retrieve the byte offset of DB_TRX_ID in a clustered index leaf page record. row_undo_mod_must_purge(): Determine if a record should be purged. row_undo_mod_clust(): For temporary tables, skip the purge checks. When rolling back an update so that the original record was not delete-marked, reset DB_TRX_ID if the history is no longer visible.
77 lines
2.4 KiB
Plaintext
77 lines
2.4 KiB
Plaintext
--source include/innodb_page_size.inc
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let INNODB_PAGE_SIZE=`select @@innodb_page_size`;
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let MYSQLD_DATADIR=`select @@datadir`;
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SET @saved_frequency = @@GLOBAL.innodb_purge_rseg_truncate_frequency;
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SET GLOBAL innodb_purge_rseg_truncate_frequency = 1;
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--echo #
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--echo # MDEV-12288 Reset DB_TRX_ID when the history is removed,
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--echo # to speed up MVCC
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--echo #
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SET GLOBAL innodb_purge_rseg_truncate_frequency = 1;
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CREATE TABLE t1(a INT PRIMARY KEY, b INT NOT NULL)
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ROW_FORMAT=REDUNDANT ENGINE=InnoDB;
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--connect (prevent_purge,localhost,root)
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START TRANSACTION WITH CONSISTENT SNAPSHOT;
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--connection default
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INSERT INTO t1 VALUES(1,2),(3,4);
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UPDATE t1 SET b=-3 WHERE a=3;
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--connect (con1,localhost,root)
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BEGIN;
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# For purgeable records, we must record DB_TRX_ID=0 in the undo log!
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UPDATE t1 SET b=4 WHERE a=3;
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--disconnect prevent_purge
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--connection default
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# Initiate a full purge, which should reset the DB_TRX_ID except for a=3.
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--source include/wait_all_purged.inc
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# Initiate a ROLLBACK of the update, which should reset the DB_TRX_ID for a=3.
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--disconnect con1
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FLUSH TABLE t1 FOR EXPORT;
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# The following is based on innodb.table_flags:
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--perl
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use strict;
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my $ps= $ENV{INNODB_PAGE_SIZE};
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my $file= "$ENV{MYSQLD_DATADIR}/test/t1.ibd";
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open(FILE, "<", $file) || die "Unable to open $file\n";
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my $page;
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print "Clustered index root page contents:\n";
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sysseek(FILE, 3*$ps, 0) || die "Unable to seek $file";
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die "Unable to read $file" unless sysread(FILE, $page, $ps) == $ps;
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print "N_RECS=", unpack("n", substr($page,38+16,2));
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print "; LEVEL=", unpack("n", substr($page,38+26,2)), "\n";
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my @fields=("a","DB_TRX_ID","DB_ROLL_PTR", "b");
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for (my $offset= 0x65; $offset;
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$offset= unpack("n", substr($page,$offset-2,2)))
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{
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print "header=0x", unpack("H*",substr($page,$offset-6,6)), " (";
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my $n_fields= unpack("n", substr($page,$offset-4,2)) >> 1 & 0x3ff;
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my $start= 0;
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my $name;
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for (my $i= 0; $i < $n_fields; $i++) {
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my $end= unpack("C", substr($page, $offset-7-$i, 1));
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print ",\n " if $i;
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print "$fields[$i]=";
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if ($end & 0x80) {
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print "NULL(", ($end & 0x7f) - $start, " bytes)"
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} else {
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print "0x", unpack("H*", substr($page,$offset+$start,$end-$start))
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}
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$start= $end & 0x7f;
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}
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print ")\n";
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}
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close(FILE) || die "Unable to close $file\n";
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EOF
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UNLOCK TABLES;
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SELECT * FROM t1;
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DROP TABLE t1;
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SET GLOBAL innodb_purge_rseg_truncate_frequency = @saved_frequency;
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