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コメント(7)

• 正解だと思う選択肢: C

  According to the documentation: Use a Universally Unique Identifier (UUID) You can use a Universally Unique Identifier (UUID) as defined by RFC 4122 as the primary key. Version 4 UUID is recommended, because it uses random values in the bit sequence. Version 1 UUID stores the timestamp in the high order bits and is not recommended.

  https://cloud.google.com/spanner/docs/schema-design

  👍 6

  Remi20212022/09/13
• 正解だと思う選択肢: B

  Answer should be B as in all the other options hotspotting is possible. According to proper schema design guideline.. Schema design best practice #1: Do not choose a column whose value monotonically increases or decreases as the first key part for a high write rate table.

  Supporting link: https://cloud.google.com/spanner/docs/schema-design#primary-key-prevent-hotspots

  👍 2

  jsree2362022/09/05
• 正解だと思う選択肢: C

  A and D are not valid, because they monotonically increase. C avoid hotspots for sure, but It's nor relate with querys. So for writing performance it's perfect that the reason for chose this:  “You need to create a new transaction table in Cloud Spanner that stores product sales data”. They only ask you to store product data, its a writing ops. If the question had spoken about query the info or hard performance read, the best option would be B, because it has the balance of writing/reading best practices. There are a few disadvantages to using a UUID:

  They are slightly large, using 16 bytes or more. Other options for primary keys don't use this much storage.
  They carry no information about the record. For example, a primary key of SingerId and AlbumId has an inherent meaning, while a UUID does not.
  You lose locality between records that are related, which is why using a UUID eliminates hotspots.
  

  https://cloud.google.com/spanner/docs/schema-design#uuid_primary_key

  👍 2

  odacir2022/12/08