x wrote:

From: E.Pasma<mailto:pasm...@concepts.nl>
Sent: 26 November 2017 17:30
To: SQLite mailing list<mailto:sqlite-users@mailinglists.sqlite.org>
Subject: Re: [sqlite] Getting an advance list of RowIDs for a query result set

If step 3 is xxx-ed and only left-joins remain to be considered then
the SQLite3 engine is likely to fullfill  this optimization in its
next release.
I tested this on the current  (2017-11-17) pre-release snapshot. As
far as I see any outer joined table may be discarded from the query
plan if only rowid from the base table is selected. Using SELECT
DISTINCT applies this also to one-to-many joins.

Thanks E. Pasma. Fixing the left join optimisation will be enough for me and will allow me to delete a fair amount of difficult code. My confusion over the inner joins arose out of trying to find a way of ensuring the BaseTbl RowIDs wouldn’t contain any duplicates. Somewhere along the line I forgot SQLite would have to still check the record existed in the inner joined table.

Thanks to you, this topic has inspired a useful change or changes.

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