bug? - unexpected data beyond EOF in block
Problem
While using `pgvector` on a table with frequent updates / inserts on Postgres 14 on macOS on Intel, I've been encountering this error frequently on `UPDATES`: [code block] Looking through the PostgreSQL mailing list about this error, most posts pertain to linux kernels from the ~2010s, and don't seem applicable. I've run `VACUUM FULL` on the table a few times, as well as completely dumping the table using `pg_dump`, deleting the table and recreating. The table is ~340 GiB and there is also a 13 GiB IVFFlat index referencing one of the `vector(768)` columns. Wondering if there might be a bug in how large vectors are stored. My table, notably, contains columns of types: - `vector(768)` - `vector(768)[]` - `character varying[]` - `character varying` And each row is easily around 2 or 3 MiB.
Error Output
error frequently on `UPDATES`:
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1 Fix
Optimize pgvector Storage and Update Strategy
The error 'unexpected data beyond EOF in block' can occur due to fragmentation and improper handling of large vector data types during frequent updates. PostgreSQL may struggle with large row sizes and the associated storage mechanisms, especially when using custom data types like pgvector. This can lead to data corruption or unexpected behavior during updates, particularly when the table is large and heavily modified.
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- 1
Analyze Table and Index Usage
Use the PostgreSQL `pg_stat_user_tables` and `pg_stat_user_indexes` views to analyze the usage patterns of your table and index. This will help identify if there are any performance bottlenecks or if the index is being used effectively.
sqlSELECT * FROM pg_stat_user_tables WHERE relname = 'your_table_name'; SELECT * FROM pg_stat_user_indexes WHERE relname = 'your_index_name'; - 2
Adjust Fillfactor for Table and Index
Set a lower fillfactor for the table and the IVFFlat index to reduce row locking and fragmentation. This allows more space for updates without needing to move rows around, which can lead to the EOF error.
sqlALTER TABLE your_table_name SET (fillfactor = 70); ALTER INDEX your_index_name SET (fillfactor = 70); - 3
Implement Batch Updates
Modify your update strategy to batch updates instead of performing them one at a time. This can reduce the frequency of locks and fragmentation. Consider using a transaction to group multiple updates together.
sqlBEGIN; UPDATE your_table_name SET column_name = new_value WHERE condition; UPDATE your_table_name SET column_name = new_value WHERE condition; COMMIT; - 4
Monitor and Adjust Autovacuum Settings
Ensure that autovacuum is configured correctly to handle the large size of your table. Adjust the autovacuum settings to run more frequently or with lower thresholds to prevent bloat.
sqlALTER TABLE your_table_name SET (autovacuum_vacuum_scale_factor = 0.01, autovacuum_vacuum_threshold = 50); - 5
Upgrade pgvector and PostgreSQL
Check for updates to the pgvector extension and PostgreSQL itself. Newer versions may contain bug fixes and performance improvements that address issues with large vector data types.
sqlSELECT version(); -- Check current PostgreSQL version -- Follow the official documentation to upgrade pgvector
Validation
After implementing these steps, monitor the database logs for the 'unexpected data beyond EOF in block' error. Additionally, run a series of updates on the table and verify that the updates complete successfully without errors. Performance metrics should also be analyzed to ensure that the changes have improved efficiency.
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Environment
Submitted by
Alex Chen
2450 rep