| = 9. Disable ElasticSearch dynamic mapping |
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| Date: 2019-10-10 |
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| == Status |
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| Accepted (lazy consensus) |
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| == Context |
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| We rely on dynamic mappings to expose our mail headers as a JSON map. |
| Dynamic mapping is enabled for adding not yet encountered headers in the mapping. |
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| This causes a serie of functional issues: |
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| * Maximum field count can easily be exceeded |
| * Field type 'guess' can be wrong, leading to subsequent headers omissions (see JAMES-2078) |
| * Document indexation needs to be paused at the index level during mapping changes to avoid concurrent changes, impacting negatively performance. |
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| == Decision |
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| Rely on nested objects to represent mail headers within a mapping |
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| == Consequences |
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| The index needs to be re-created. |
| Document reIndexation is needed. |
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| This solves the aforementionned bugs (see JAMES-2078). |
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| Regarding performance: |
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| * Default message list performance is unimpacted |
| * We noticed a 4% performance improvment upon indexing throughput |
| * We noticed a 7% increase regarding space per message |
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| == References |
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| * https://github.com/linagora/james-project/pull/2726[JAMES-2078] JAMES-2078 Add an integration test to prove that dynamic mapping can lead to ignored header fields |
| * https://issues.apache.org/jira/browse/JAMES-2078[JIRA] |
