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InnoDB 1.1 for MySQL 5.5 User's Guide
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6.3.3. Possible Inconsistency with PROCESSLIST

As just described, while the transaction and locking data is correct and consistent when these INFORMATION_SCHEMA tables are populated. For example, the query in INNODB_TRX is always consistent with the rest of INNODB_TRX, INNODB_LOCKS and INNODB_LOCK_WAITS when the data comes from the same snapshot. However, the underlying data changes so fast that similar glimpses at other, similarly fast-changing data, may not be in synchrony. Thus, you should be careful in comparing the data in the InnoDB transaction and locking tables with that in the PROCESSLIST table. The data from the PROCESSLIST table does not come from the same snapshot as the data about locking and transactions. Even if you issue a single SELECT (joining INNODB_TRX and PROCESSLIST, for example), the content of those tables is generally not consistent. INNODB_TRX may reference rows that are not present in PROCESSLIST or the currently executing SQL query of a transaction, shown in INNODB_TRX.TRX_QUERY may differ from the one in PROCESSLIST.INFO.

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