Does ignite support Read-consistent queries?

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prasadbhalerao1983 prasadbhalerao1983
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Does ignite support Read-consistent queries?


Read-consistent queries: Queries that produce consistent results with respect to a point in time.

Please check this article. I am speaking w.r.t. this article.

Oracle uses the information stored in rollback segments to provide this read consistent view of information. Since the rollback segments are where Oracle stores "old values" or before images of data during transaction processing, it can use these old values to provide a query with the value of data as it looked in the database when the query began. As a query processes the blocks of data in a table, it will see if the data on that block has changed since the query began. If it has Oracle will read the information from the rollback segment to determine what the block looked like when the query began, that is the view of the data the query will see. This is how non-blocking reads are implemented as well - Oracle only looks to see if the data changed, it does not care of the data is currently locked (which implies that it has changed). It will simply retrieve the old value from the rollback segment and proceed onto the next block of data. 

Does ignite support this?


Thanks,
Prasad
Stanislav Lukyanov Stanislav Lukyanov
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RE: Does ignite support Read-consistent queries?

Ignite transactions support this with REPEATABLE_READ isolation level.

More info here: https://apacheignite.readme.io/docs/transactions

 

Stan

 

From: [hidden email]
Sent: 9 июля 2018 г. 14:50
To: [hidden email]
Subject: Does ignite support Read-consistent queries?

 

 

Read-consistent queries: Queries that produce consistent results with respect to a point in time.

 

Please check this article. I am speaking w.r.t. this article.

 

Oracle uses the information stored in rollback segments to provide this read consistent view of information. Since the rollback segments are where Oracle stores "old values" or before images of data during transaction processing, it can use these old values to provide a query with the value of data as it looked in the database when the query began. As a query processes the blocks of data in a table, it will see if the data on that block has changed since the query began. If it has Oracle will read the information from the rollback segment to determine what the block looked like when the query began, that is the view of the data the query will see. This is how non-blocking reads are implemented as well - Oracle only looks to see if the data changed, it does not care of the data is currently locked (which implies that it has changed). It will simply retrieve the old value from the rollback segment and proceed onto the next block of data. 

 

Does ignite support this?

 

 

Thanks,

Prasad