[DYOD] Maintain UCCs in face of potentially changing data 8000 #2599
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This was referenced Aug 2, 2023
SanJSp
reviewed
Aug 4, 2023
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Hey all, I reviewed your code in the name of Team 3.
First of all: Good job with the implementation!
I checked mainly for hyrise coding standards, which were all pretty well followed. I already started to look inside your comments to find stuff I could pick on 😁 So I think this is a pretty good sign. Likewise, I've tried to add some comments regarding const in between, sometimes I was not too sure if it's applicable. Feel free to try it out and if it works implement it, if not, so be it 😊
I will take a look at the other PR as well 😊
Co-authored-by: kalathen <kalathen@jyu.fi> Co-authored-by: Margarete <margarete.dippel@student.hpi.de>
… become invalid Co-authored-by: kalathen <kalathen@jyu.fi> Co-authored-by: Margarete <margarete.dippel@student.hpi.de>
Co-authored-by: kalathen <kalathen@jyu.fi> Co-authored-by: Margarete <margarete.dippel@student.hpi.de>
…id using MVCC data Co-authored-by: kalathen <kalathen@jyu.fi> Co-authored-by: Margarete <margarete.dippel@student.hpi.de>
Co-authored-by: kalathen <kalathen@jyu.fi> Co-authored-by: Margarete <margarete.dippel@student.hpi.de>
…Cs becoming invalid and vice versa Co-authored-by: kalathen <kalathen@jyu.fi> Co-authored-by: Margarete <margarete.dippel@student.hpi.de>
Co-authored-by: kalathen <kalathen@jyu.fi> Co-authored-by: Margarete <margarete.dippel@student.hpi.de>
Co-authored-by: kalathen <kalathen@jyu.fi> Co-authored-by: Margarete <margarete.dippel@student.hpi.de>
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dey4ss
reviewed
Sep 28, 2023
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Put this on hold until end of August. We plan to incorporate this feature, but there is currently no capacity for it. Will work on it when back from the internship. |
…D` from mvcc_data to types.h
…eyConstraint is schema-given. Also add `ETERNAL_COMMIT_ID` and `INITIAL_COMMIT_ID` to types.hpp
Co-authored-by: Daniel Lindner <27929897+dey4ss@users.noreply.github.com>
…berg/maintain_data_dependencies
…berg/maintain_data_dependencies
… key constraints that are confidently valid for optimization
…berg/maintain_data_dependencies
Base automatically changed from
robert/add-locking-for-table-constraints
to
master
June 4, 2025 15:08
dey4ss
reviewed
Jun 17, 2025
- rename `TableKeyConstraint::is_valid` to `last_validation_result` and use `ValidationResultType` enum - skip probing for chunks with no inserts since last ucc validation - assert that key constraints of type primary key are always schema-given
dey4ss
reviewed
Jun 18, 2025
Co-authored-by: Daniel Lindner <27929897+dey4ss@users.noreply.github.com>
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UCCs(Unique Column Combinations) indicate the uniqueness across all entries of a column (or a set of columns). UCCs can be given by the schema (a primary key guarantees uniqueness), but also happen "incidentally" in real-world data.Because UCCs can be used for query optimization, we want to detect these "incidental" UCCs as well, because, for optimization purposes, we can use them just as we would use a primary key constraint.
Before this PR, hyrise was already capable to detect such UCCs. It did so by actually generating
UNIQUEconstraints on a table, which are translated into UCCs during query optimization. However, this discovery happened under the assumption that the data of the table never changes. This means, if the data of the table were to change and violate the previously discovered "incidental" UCC by creating a duplicate value in the targeted column, this using the UCC for query optimization would lead to incorrect query results.Therefore, in this MR, we assign a validation
commit IDto the TableKeyConstraint (UCC) such that it may be only used for optimization if the table has not seen any changes since thiscommit ID(note that every modifying transaction increments the globalcommit ID). We will then regularly revalidate the UCC and see if we can expand the constraint to larger commit IDs.For optimization purposes, we also make use of the
MVCC(Multi-Version Concurrency Control) data of chunks, which includes but is not limited to thecommit IDsof when any data was last inserted to or deleted from the chunk (note that hyrise models modifications as delete+insert).