branch-4.0: [Feature](iceberg) Add manifest-level cache for Iceberg tables to reduce I/O and parsing overhead #59056 #59408
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…uce I/O and parsing overhead (#59056) ### What problem does this PR solve? ## Motivation During Iceberg query planning, FE needs to read and parse the metadata chain: ManifestList → Manifest → DataFile/DeleteFile. When frequently querying hot partitions or executing small batch queries, the same Manifest files are repeatedly read and parsed, causing significant I/O and CPU overhead. ## Solution This PR introduces a manifest-level cache (`IcebergManifestCache`) in FE to cache the parsed DataFile/DeleteFile lists per manifest file. The cache is implemented using Caffeine with weight-based LRU eviction and TTL support. ### Key Components - **IcebergManifestCache**: Core cache implementation using Caffeine - Weight-based LRU eviction controlled by `iceberg.manifest.cache.capacity-mb` - TTL expiration via `iceberg.manifest.cache.ttl-second` - Single-flight loading to prevent duplicate parsing of the same manifest - **ManifestCacheKey**: Cache key consisting of: - Manifest file path - **ManifestCacheValue**: Cached payload containing: - List of `DataFile` or `DeleteFile` - Estimated memory weight for eviction - **IcebergManifestCacheLoader**: Helper class to load and populate the cache using `ManifestFiles.read()` ### Cache Invalidation Strategy - Key changes automatically invalidate stale entries (length/lastModified/sequenceNumber changes) - TTL prevents stale data when underlying storage doesn't support precise mtime/etag - Different snapshots use different manifest paths/keys, ensuring snapshot-level isolation ### Iceberg Catalog Properties | Config | Default | Description | |--------|---------|-------------| | `iceberg.manifest.cache.enable` | `true` | Enable/disable manifest cache | | `iceberg.manifest.cache.capacity-mb` | `1024` | Maximum cache capacity in MB | | `iceberg.manifest.cache.ttl-second` | `48 * 60 * 60` | Cache entry expiration after access | ### Integration Point The cache is integrated in `IcebergScanNode.planFileScanTaskWithManifestCache()`, which: 1. Loads delete manifests via cache and builds `DeleteFileIndex` 2. Loads data manifests via cache and creates `FileScanTask` for each data file 3. Falls back to original scan if cache loading fails
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yiguolei
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Jan 7, 2026
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PR approved by at least one committer and no changes requested. |
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PR approved by anyone and no changes requested. |
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Cherry-picked from #59056