Hi all, I open PIP-404 to introduce per ledger properties, which will add a `properties` field to `LedgerInfo` to store extra properties for every `Ledger`.
# Background knowledge As we don't have a secondary index on the Bookkeeper, so we can't query entries by message metadata efficiently. The `ManagedCursor` provides a method `asyncFindNewestMatching` to find the newest entry that matches the given predicate by binary search(See `OpFindNewest.java`). In https://github.com/apache/pulsar/pull/22792, we optimized `seeking by timestamp` by calculating the range of ledgers that may contain the target timestamp by `LedgerInfo#timestamp` and we don't need to scan all ledgers. However, when we enabled `AppendIndexMetadataInterceptor` and we want to query entries by `BrokerEntryMetadata#index`, there is no more efficient way, we have to scan all ledgers by binary search to find the target entry. # Motivation Introduce per-ledger properties and we can store the extra per-ledger properties in the `LedgerInfo`, so we can query entries by `incremental index` more efficiently, say, `BrokerEntryMetadata#index`. PR link: https://github.com/apache/pulsar/pull/23837/files Please help review the PIP and vote. Thanks, Tao Jiuming(dao-jun)
