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Hi, we plan to to install a read only scale out system. Is there any experiences what are the performance effect on the root node when I execute a large statement on the copy node ? If a table on the copy node is blocked during a transaction, changes on the root node that affect a corresponding table are blocked ? thank you Andreas |
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Read-only scale-out is particularly meant to separate long-running (and "heavy-locking") queries on copy nodes from OLTP on the root node. AFAIK, the root node works somewhat as in asynchronous mirror mode of a mirror-setup, i.e. it does not wait for the copy nodes to acknowledge the successful transmission of the sent log pages to the copy node's transaction log. Therefore, a query on the copy nodes should not at all block any transaction on the root node. 1
Many thanks "The root node does not wait for the copy nodes to acknowledge the successful transmission". This is what I was looking for. thank you
(23 Nov '21, 07:37)
AZiehn
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> If a table on the copy node is blocked during a transaction
AFAIK that's not going to happen because the copy node is read only.