mongodb data_error ai_generated true

MongoServerError: IndexKeyTooLarge: index key for compound index 'idx_1_2_3' on namespace test.events has key size 1050 bytes, which exceeds the maximum index key size of 1024 bytes

ID: mongodb/index-key-too-large-for-compound-index

Also available as: JSON · Markdown · 中文
78%Fix Rate
89%Confidence
1Evidence
2023-09-18First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
mongodb-5.0 active — — —
mongodb-6.0 active — — —
mongodb-7.0 active — — —
mongodb-8.0 active — — —

Root Cause

The combined size of indexed fields in a document exceeds MongoDB's 1024-byte index key limit, often due to large string or array values.

generic

中文

文档中索引字段的组合大小超过了 MongoDB 的 1024 字节索引键限制，通常由于大字符串或数组值导致。

Official Documentation

https://www.mongodb.com/docs/manual/reference/limits/#Index-Key-Limit

Workarounds

  1. 85% success Reduce the size of indexed fields by truncating long strings or using smaller data types (e.g., ObjectId instead of string IDs). 
    Reduce the size of indexed fields by truncating long strings or using smaller data types (e.g., ObjectId instead of string IDs).
  2. 80% success Use a partial index that only indexes documents with smaller field values to avoid the limit. 
    Use a partial index that only indexes documents with smaller field values to avoid the limit.
  3. 70% success Split the compound index into separate indexes and use $or queries to combine them, though this may affect performance. 
    Split the compound index into separate indexes and use $or queries to combine them, though this may affect performance.

中文步骤

  1. Reduce the size of indexed fields by truncating long strings or using smaller data types (e.g., ObjectId instead of string IDs).
  2. Use a partial index that only indexes documents with smaller field values to avoid the limit.
  3. Split the compound index into separate indexes and use $or queries to combine them, though this may affect performance.

Dead Ends

Common approaches that don't work:

  1. 50% fail

    Increasing the index key limit is not possible; it is a hard limit in MongoDB.

  2. 50% fail

    Dropping the compound index and creating multiple single-field indexes may degrade query performance for multi-field queries.

  3. 50% fail

    Using a hashed index on all fields reduces query flexibility and does not support range queries.