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Displaying posts with tag: Aleksandr Kuzminsky (reset)

Checking B+tree leaf nodes list consistency in InnoDB
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If we have InnoDB pages there are two ways to learn how many records they contain:

  • PAGE_N_RECS field in the page header
  • Count records while walking over the list of records from infimum to supremum

In some previous revision of the recovery tool a short summary was added to a dump which is produced by the constraints_parser.

But if a page is lost and page_parser hasn’t found it, all records from this page are lost. In other words per-page recovery statistics gives us little idea about whether or not a recovered table is complete.

To cover this flaw a new tool index_check is introduced in

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Recovering temporal types in MySQL 5.6: TIME, TIMESTAMP and DATETIME
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MySQL 5.6 introduces a new feature – microseconds resolution in some temporal types. As of 5.6.4 TIME, TIMESTAMP and DATETIME can have a fractional part. To create a field with subseconds you can specify precision in brackets: TIME(3), DATETIME(6) etc.

Obviously, the new feature requires the format change. All three types may now have a tail with a fractional part. The tail may be one, two or three bytes long and can store up to six digits after the point.

The non-fractional part has changed too. Thus, DATETIME uses only five bytes comparing to eight in previous versions.

As of

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Showing entries 1 to 2

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