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Fix invariants optimization involving views (#7388)#7390

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dyemanov merged 1 commit intomasterfrom
view-invariants
Dec 16, 2022
Merged

Fix invariants optimization involving views (#7388)#7390
dyemanov merged 1 commit intomasterfrom
view-invariants

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@dyemanov dyemanov commented Nov 16, 2022

The idea is that we should not compare view field's stream with streams from other RSEs until the field has been expanded to the proper expression. Once it's done, sub->pass1() will recursively take care of the invariant checking. The test case from #7388 now shows good performance in both cases, but I'd like to have a second opinion.

@dyemanov dyemanov self-assigned this Nov 16, 2022
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livius2 commented Nov 17, 2022

Is it possible to see difference of such execution in explain plan?
As now both plans are equal. Do you consider some extension to it?

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dyemanov commented Nov 17, 2022

I agree it could be useful. Will take look at possible implementation.

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dyemanov commented Nov 26, 2022

This is the suggested plan output:

Sub-query (invariant)
    -> Singularity Check
        -> Aggregate
            -> Nested Loop Join (outer)
                -> Filter
                    -> Hash Join (inner)
                        -> Table "RDB$RELATION_FIELDS" as "SUB RF" Full Scan
                        -> Record Buffer (record length: 529)
                            -> Table "RDB$RELATIONS" as "SUB R" Full Scan
                -> Filter
                    -> Table "RDB$SECURITY_CLASSES" as "SUB SC" Access By ID
                        -> Bitmap
                            -> Index "RDB$INDEX_7" Unique Scan
Select Expression
    -> Filter
        -> Nested Loop Join (outer)
            -> Nested Loop Join (inner)
                -> Filter
                    -> Table "RDB$RELATIONS" as "SUB R" Access By ID
                        -> Bitmap
                            -> Index "RDB$INDEX_1" Range Scan (full match)
                -> Filter
                    -> Table "RDB$RELATION_FIELDS" as "SUB RF" Access By ID
                        -> Bitmap
                            -> Index "RDB$INDEX_4" Range Scan (full match)
            -> Filter
                -> Table "RDB$SECURITY_CLASSES" as "SUB SC" Access By ID
                    -> Bitmap
                        -> Index "RDB$INDEX_7" Unique Scan

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livius2 commented Nov 26, 2022 •
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Will be good to see both plans in new version.
It will be now like this?

Sub-query (invariant)
    -> Singularity Check

and second version

Select Expression
    -> Singularity Check

or it will look differently?

Sub-query (invariant)
    -> Singularity Check

and second version

Sub-query (variant)
    -> Singularity Check

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dyemanov commented Nov 26, 2022

"Select Expression" is the main query, it does not change. For sub-query now we see also "Select Expression", after the patch it will look as either "Sub-query" or "Sub-query (invariant)".

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dyemanov commented Nov 26, 2022

Most sub-queries are correlated in practice, so reporting them as "variant" IMO is about to cause more questions than keeping is simple.

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livius2 commented Nov 26, 2022 •
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Yes, my concern was only if for variant there will be Select Expression or also Sub-query :)

@dyemanov dyemanov merged commit 0ec40cc into master Dec 16, 2022
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dyemanov commented Dec 16, 2022

Plan explain improvements will be applied separately.

@dyemanov dyemanov mentioned this pull request Jan 2, 2023
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@dyemanov dyemanov deleted the view-invariants branch May 12, 2023 14:37
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component: engine fix-version: 5.0 Beta 1 type: bug

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