Normalize schema fingerprint for column permutations#17044
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abhishekagarwal87 merged 7 commits intoapache:masterfrom Sep 18, 2024
Merged
Normalize schema fingerprint for column permutations#17044abhishekagarwal87 merged 7 commits intoapache:masterfrom
abhishekagarwal87 merged 7 commits intoapache:masterfrom
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added 3 commits
September 12, 2024 20:03
…se for different column permutations
cryptoe
approved these changes
Sep 16, 2024
| // thus avoiding schema explosion in the metadata database | ||
| // Note that this signature is not persisted anywhere, it is only used for fingerprint computation | ||
| final RowSignature sortedSignature = getLexicographicallySortedSignature(schemaPayload.getRowSignature()); | ||
| final SchemaPayload updatedPayload = new SchemaPayload(sortedSignature, schemaPayload.getAggregatorFactories()); |
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Please mention a note about the aggregator factories as well that they are column order independent since they are backed by a map.
added 4 commits
September 17, 2024 10:29
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Parent issue: #14989
It is possible for the order of columns to vary across segments especially during realtime ingestion.
Since, the schema fingerprint is sensitive to column order this leads to creation of a large number of segment schema in the metadata database for essentially the same set of columns.
This is wasteful, this patch fixes this problem by computing schema fingerprint on lexicographically sorted columns. This would result in creation of a single schema in the metadata database with the first observed column order for a given signature.
Release notes
In the CentralizedDatasourceSchema feature, different permutations of the same column order do not result in distinct schemas in the database.