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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

asked 23 Nov '21, 04:03

AZiehn's gravatar image

AZiehn
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accept rate: 0%

> 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.

(23 Nov '21, 06:52) Breck Carter

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.

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answered 23 Nov '21, 05:54

Volker%20Barth's gravatar image

Volker Barth
40.5k365556827
accept rate: 34%

converted 23 Nov '21, 09:25

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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question asked: 23 Nov '21, 04:03

question was seen: 568 times

last updated: 23 Nov '21, 07:37