[jitl]

You do not want to use IndexedDB, you should avoid IndexedDB if you can make live work without it.

IndexedDB rows need to be very coarse grained, each operation with the IndexedDB API has very high overhead compared to something like walking a LSM tree in RocksDB or something. If the index does fit in memory, then the best move would be to store and load the entire index from a single or a few IndexedDB rows.

If you need to index a lot of documents in a way that doesn't fit in memory, I recommend you consider sqlite3, stored in either OPFS or on IndexedDB, and use sqlite's FTS5 full text search stuff for the index. There are several sqlite backends available (see https://github.com/rhashimoto/wa-sqlite/tree/master/src/exam...), something like their IDB VFS will store each block in the sqlite file as a row in IndexedDB essentially batching storage of the index rows into IDB rows for you (for more details read https://github.com/rhashimoto/wa-sqlite/blob/3c202615ed6f54e...)