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SQL: Index can return too many entries when used with `ORDER BY` #1760

Open gramian opened 3 days ago

gramian commented 3 days ago

ArcadeDB Version:

ArcadeDB Server v24.11.1-SNAPSHOT (build 4207821d055e37cbd74b76683e45073da759c2de/1729083296142/console)

OS and JDK Version:

Running on Mac OS X 12.7.6 - OpenJDK 64-Bit Server VM 17.0.12 (Homebrew)

Querying a database can return the wrong number of records, in particular too many records. This problem is not easy to reproduce so I attach a small database (75 records) generated from public data. This behavior occurs when from certain databases, such as the one provided below, is queried via SQL, ie SELECT, where an (not-unique) indexed property is used in the projection and also as ordering quantity (in ORDER BY). The schema is given here: https://github.com/ulbmuenster/dataasee/blob/main/database/schema.sql

Expected behavior

Correct number of records returned.

Actual behavior

Too many records are returned.

Steps to reproduce

Restore this backup: metadatalake-backup-20240829-100753793.zip (337KB)

SELECT count(*) FROM metadata; -- There are 75 records in the database

SELECT name, publicationYear FROM metadata; -- Returns 75 records correctly

SELECT name FROM metadata ORDER BY publicationYear; -- Returns 75 records correctly

SELECT name, publicationYear FROM metadata ORDER BY publicationYear; -- Returns 117 records INCORRECTLY

Notes

End of August (2024-08-28 -- 2024-08-31) @lvca (and I) looked into this and potential sources of this behavior could be:

Here is a sample UPSERT statement that generated the provided database:

UPDATE metadata MERGE {"creators":[{"@type":"pair","name":"Neumann, Georg"},{"@type":"pair","name":"Boivin, Odette"},{"@type":"pair","name":"Kleber, Kristin"},{"@type":"pair","name":"Neumann, Georg"},{"@type":"pair","name":"Boivin, Odette"},{"@type":"pair","name":"Kleber, Kristin"}],"dataLocation":"https://data-management.uni-muenster.de/direct-access/wwurdm/07988641231","dataSteward":"https://datastore.uni-muenster.de","description":"The dataset comprises the RTI-data of the cuneiform tablet VAT 17966 (N5:27).\\n\\nRTI = Reflectance Transformation Imaging (RTI) is a computational photographic method that captures a subject’s surface shape and color and enables the interactive re-lighting of the subject from any direction in a software viewer, revealing details not visible with the naked eye (cf. https://culturalheritageimaging.org/).","identifiers":[{"@type":"pair","data":"10.17879/07988641225","name":"DE-6"},{"@type":"pair","data":"10.17879/07988641225","name":"null"}],"keywords":"Babylon,Cuneiform,Neo-Babylonian","language":"#4:0","metadataQuality":"Incomplete","name":"VAT 17966 - RTI dataset","publicationYear":2024,"publisher":"Universität Münster","rawChecksum":"TcrJlnTQYfugD2rROs2Y3g==","rawType":"marc21","recordId":"MTA0MzQ4NDE4NDMwODAyNDg3NA","resourceType":null,"rights":"CC BY-NC-SA 4.0","source":"https://datastore.uni-muenster.de/oai","synonyms":[{"@type":"pair","data":"GoviB","name":"Alternative Title"}]} UPSERT WHERE recordId == 'MTA0MzQ4NDE4NDMwODAyNDg3NA';

As a workaround the projection can be renamed, ie:

SELECT name, publicationYear AS pubYear FROM metadata ORDER BY publicationYear;

but this also excludes the use of the index!

gramian commented 2 days ago

Using either UPDATE ... MERGE ... UPSERT or UPDATE ... CONTENT ... UPSERT produces too many index results.