Hi all My questions are: Thanks. |
As to the docs your third question is confirmed:
Can't comment on the PostgreSQL behaviour but for row versioning details, see my older question here. (*): Unless it's "readonly-statement-snapshot" combined with "read uncommitted" and you are using updatable statements, see here. See the linked question und Glenn's inevitable sound explanation, SQL Anywhere does also only create copies of the "before state" when an update occurs, not when a row is read. Those rows are contained in the temporary file so I don't think you can "select" those explicitly, see the database property "VersionStorePages" for a number of those pages. I guess to check the behaviour, you need to have according read transactions that access older vs. newer versions of some rows, see this simple sample from the docs.
(11 Aug '22, 11:08)
Volker Barth
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