Is there a way to retroactively create time/node based UUID in PHP?

Most time-based (type 1) UUIDs are created using the current time. I'm migrating a MySQL database to cassandra and would like to create timebased UUIDs for archived items. Can someone provide an example of how type-1 UUIDs are created using past tim开发者_如何学Ce periods?

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All uuids version 1 are a combination of node identifier (MAC address), timestamp and a random seed.

Yes its possible. The process is reversible.

From RFC4122 about the timestamp part of UUID version 1 (section 4.1.4):

"For UUID version 1, this is represented by Coordinated Universal Time (UTC) as a count of 100-nanosecond intervals since 00:00:00.00, 15 October 1582 (the date of Gregorian reform to the Christian calendar)."

Basic algorithm (section 4.2.1) for creating time base UUID (uuid version 1)

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This should be the proper way to create UUIDs based on the past time in MySQL, but database reports duplicates:

UPDATE table
SET uuid = CONCAT(
  SUBSTRING(LOWER(HEX((CAST( 1000*created_timestamp AS UNSIGNED INTEGER) + (141427 * 24 * 60 * 60 * 1000)) * 1000 * 10)), 8, 8),
  '-',
  SUBSTRING(LOWER(HEX((CAST( 1000*created_timestamp AS UNSIGNED INTEGER) + (141427 * 24 * 60 * 60 * 1000)) * 1000 * 10)), 4, 4),
  '-',
  SUBSTRING(UUID(), 15, 1),
  SUBSTRING(LOWER(HEX((CAST(1000*created_timestamp AS UNSIGNED INTEGER) + (141427 * 24 * 60 * 60 * 1000)) * 1000 * 10)), 1, 3),
  '-',
  SUBSTRING(UUID(), 20, 17))

When altering first 5 chars instead of 8 chars it seems to work fine:

UPDATE table
SET uuid = CONCAT(
  SUBSTRING(LOWER(HEX((CAST( 1000*created_timestamp AS UNSIGNED INTEGER) + (141427 * 24 * 60 * 60 * 1000)) * 1000 * 10)), 8, 5),
  SUBSTRING(UUID(), 6, 3),
  '-',
  SUBSTRING(LOWER(HEX((CAST( 1000*created_timestamp AS UNSIGNED INTEGER) + (141427 * 24 * 60 * 60 * 1000)) * 1000 * 10)), 4, 4),
  '-',
  SUBSTRING(UUID(), 15, 1),
  SUBSTRING(LOWER(HEX((CAST( 1000*created_timestamp AS UNSIGNED INTEGER) + (141427 * 24 * 60 * 60 * 1000)) * 1000 * 10)), 1, 3),
  '-',
  SUBSTRING(UUID(), 20, 17))

To check timestamp of UUIDs you can use:

SELECT FROM_UNIXTIME(
        (CONV(
            CONCAT(
                SUBSTRING(uuid, 16, 3),
                SUBSTRING(uuid, 10, 4),
                SUBSTRING(uuid, 1, 8)
            ), 16, 10)
            DIV 10 DIV 1000 DIV 1000
        )
        -
        (141427 * 24 * 60 * 60)
    ) AS uuid_timestamp
FROM table;