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Cassandra: four catalog and queue metadata reads on the data path run at LOCAL_ONE and feed a write or a cleanup

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Valutazione

Difficoltà
4/5
Tempo stimato
3-5 giorni
Idoneità per principianti
54/100
Tipo di issue
Bug
Chiarezza
Abbastanza chiara
Stato di attività
Attiva
Stack tecnologico
cassandra, rust
Ambito
backend, databases

Direzione di ricerca

Start with the four reads in crates/storage-cassandra/src/data/index.rs and data/ttl.rs, then trace ttl_config_for_table in metadata_engine.rs and the catalog writes in create_table.rs and update_table.rs. Check how Cassandra consistency levels are set and which writes each read must intersect; the issue identifies the affected operations and failure cases. Done means those reads cannot miss the catalog or queue state they use for writes and cleanup.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

backend:cassandra

Summary

Four reads of catalog and queue metadata on the Cassandra data path run at LOCAL_ONE and feed a write or a cleanup. Each can miss a row written moments earlier at LOCAL_QUORUM on a keyspace with a replication factor above 1. None changes what a base-table GetItem, Query or Scan with ConsistentRead: true returns, so they were left out of #560 (fixed in #591).

The four reads

Read File Feeds A missed row means
fetch_indexes_for_table on the put, update and delete paths crates/storage-cassandra/src/data/index.rs (fetch_indexes_for_table_at(.., false)) the set of GSI rows a write maintains a write after an UpdateTable that added a GSI writes no index row for the item; if the backfill already passed its range, the GSI never holds the item
the gsi_pending last_ready_at read data/index.rs the clamp ready_at_ms = max(jittered, last_ready_at + 1) that orders async GSI mutations a later mutation of the same worker partition can take an earlier ready_at, so the GSI can end on the older image
delete_indexes_for_table data/index.rs the index ids whose data tables DeleteTable drops an index's data table is left undropped after its catalog rows are deleted
the TTL bucket read in clear_ttl_entries data/ttl.rs the queue partitions deleted when TTL is disabled queue rows left behind after the registration is removed

The write paths also read the TTL configuration through ttl_config_for_table (metadata_engine.rs), which runs through cassandra_util::query_rows at the driver default outside data/; a write that misses a TTL just enabled inserts no expiration entry.

Expected

The gsi_pending read decides a write and the rows it reads are written at LOCAL_QUORUM inside data/, so passing true there closes it in one argument. The other three read catalog rows that CreateTable and UpdateTable write at the driver default outside data/, so a quorum read alone does not intersect those writes; the catalog writes need a stated level first.

Where

  • crates/storage-cassandra/src/data/index.rs
  • crates/storage-cassandra/src/data/ttl.rs
  • crates/storage-cassandra/src/metadata_engine.rs (ttl_config_for_table)
  • crates/storage-cassandra/src/create_table.rs, update_table.rs (the catalog writes)
Lingua principale
Rust
Stelle
517
Fork
60
Merge medio
4g 10h
PR unite (30g)
37

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