electrs crashes while indexing mainnet with "Too many open files"

Electrs new-index works fine for testnet but while syncing mainnet, errors out with -

(Truncated log)
```
TRACE - skipping block 0000000000000000001a871a0c81fe392e9d90562e702eddd2835e27da815f1d
TRACE - skipping block 0000000000000000001198ed4b9090ef67acebc8ca517bdcd67efc930e554b6c
TRACE - skipping block 0000000000000000001c02b01cb173dc33cd901d0842be6f331037c03b1b1afa
TRACE - skipping block 000000000000000000131227a7c21c0c247b5ee30aeffbd1f9ccba6038d071d5
TRACE - skipping block 0000000000000000000c99cf30cb7609a3d3e1bc6b65c6360b03130e34b2f150
TRACE - fetched 9 blocks
DEBUG - writing 98889 rows to RocksDB { path: "./db/mainnet/newindex/txstore" }, flush=Disable
DEBUG - starting full compaction on RocksDB { path: "./db/mainnet/newindex/txstore" }
DEBUG - finished full compaction on RocksDB { path: "./db/mainnet/newindex/txstore" }
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error { message: "IO error: While open a file for random read: ./db/mainnet/newindex/txstore/000938.sst: Too many open files" }', src/libcore/result.rs:997:5
Aborted (core dumped)
```

Also, the size of `./db` is ~325GB. Is this normal?