update destroying.md

Update the full-replacement example graph to show the transitive
dependency that is required for the destroy-then-update case. Add
another example describing the case where we reduce the graph to
only an update and replace and the dependency on the destroy node
remains.
This commit is contained in:
James Bardin 2021-03-22 15:05:53 -04:00
parent 0bc64e3cc4
commit dcb12195a3
3 changed files with 23 additions and 0 deletions

View File

@ -114,6 +114,7 @@ digraph replacement {
} }
a -> a_d; a -> a_d;
a -> b_d [style=dotted];
b -> a_d [style=dotted]; b -> a_d [style=dotted];
b -> b_d; b -> b_d;
} }
@ -158,6 +159,28 @@ While the dependency edge from `B update` to `A destroy` isn't necessary in
these examples, it is shown here as an implementation detail which will be these examples, it is shown here as an implementation detail which will be
mentioned later on. mentioned later on.
A final example based on the replacement graph; starting with the above
configuration where `B` depends on `A`. The graph is reduced to an update of
`A` while only destroying `B`. The interesting feature here is the remaining
dependency of `A update` on `B destroy`. We can derive this ordering of
operations from the full replacement example above, by replacing `A create`
with `A update` and removing the unused nodes.
![Replace All](./images/destroy_then_update.png)
<!--
digraph destroy_then_update {
subgraph update {
rank=same;
a [label="A update"];
}
subgraph destroy {
rank=same;
b_d [label="B destroy"];
}
a -> b_d;
}
-->
## Create Before Destroy ## Create Before Destroy
Currently, the only user-controllable method for changing the ordering of Currently, the only user-controllable method for changing the ordering of

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