changes "during checkpointing" - Mailing list pgsql-general

From Sahagian, David
Subject changes "during checkpointing"
Date
Msg-id F3CBFBA88397EA498B22A05FFA9EC49D0109CD8202@MX22A.corp.emc.com
Whole thread Raw
Responses Re: changes "during checkpointing"  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-general

In regards to 9.1.x, I would like to learn some details of the nature of “checkpointing”

 

=== Question 1 ===

 

- page 123 is dirty

 

- "checkpointing" starts

 

- page 123 gets written to disk, as part of this checkpoint

 

- page 123 gets modified again

  ? Does it get written to disk again, as part of this checkpoint?

 

- "checkpointing" finishes

 

 

=== Question 2 ===

 

- page 123 is dirty

 

- "checkpointing" starts

 

- page 123 gets modified again

 

- page 123 gets written to disk, as part of this checkpoint

  ? So does the most recent mod get written to disk, even if that mod is not committed yet ?

 

- "checkpointing" finishes

 

 

=== Question 3 ===

 

When does the full-page-writing to WAL happen ?

Is it after the start of the "checkpointing" or after the finish of the "checkpointing" ?

 

 

Thanks,

-dvs-

 

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