In my preliminary tests, the patch has worked wonderfully. In these
first tests i have only tested plain SQLite functionality (without
virtual table or additional functions) on a 1.5GB DB. Some remarks:
- It is lightning fast. For queries that fit to the free space (some of
them could not finish before due to space constraints) and previously
took minutes to finish, with the patch they are instantaneous and they
do not touch the drive. The results are the same.
- I was expecting that only simple scans over unioned queries would be
affected by the patch. When i tried to do a filter on a unioned table
composition, and the query was again instantaneous, i was flabbergasted.
The patch really pushes index accesses downwards into the unioned
tables. I didn't expect the patch to go that far. I'm amazed,
- Group by on unioned all tables was also instantaneous without filling
the hard disk.
- Oddly, order by works the same both with the patch and without the
patch (SQLite 3.7.14.1). I assume that order by had a similar
optimization in previous versions of SQLite too?
- On all of the above tests, the free space on the hard disk wasn't
affected by the running query.
More tests will be done in the context of madIS, but they will take more
time. I want to test plain SQLite first, because this is what most
people will use in practise.
Best regards,
lefteris.
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