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It's possible, but it was a very simple database layout. Pretty hard to screw up. Then again, I screw up simple things all the time. But whatever I screwed up would likely have been duplicated on the postgres side since the sqlite and postgres setups were nearly identical. Postgres performed fine compared to sqlite. It was a bit behind leveldb, but I figure the overhead of flushing the data to a socket has an added cost. Leveldb has the advantage of being in the same process.

If I remember right: Querying for leveldb was iteration from [20-byte-hash][lo-utxo-id] to [20-byte-hash][hi-utxo-id] and subsequent lookups on the keys containing the actual data. The sql table setup was `id` as a char primary key and `address` as a char with an index. The query was a simple `select data from utxos where address = ?`. The actual `data` blob was on average maybe 60 bytes in size.

Maybe there was something I could have done better there. I'm not sure. This was just my experience. This is all beside the point anyway. My point was whatever database was better, it was worth testing each one, and I don't consider it to be premature optimization.

`select * from utxos where address =?` should not take 300ms no matter the size or type of database (assuming there is an index on address).

Not really. If your table does not fit into memory, there is a good chance that a disk seek is required. Now all bets are off.

By table you mean index, right ? What matters most is the size of the index, and most index data structures (see btrees) work so that very few disk seeks are needed, even if the index is large.

Perhaps if you're using a really slow spinning disk and have no indexes, or the results are distributed evenly across the entire dataset (i.e lots of random, non sequential access).

It's just 300ms is really slow, even with a largeish dataset that doesn't fit into memory. Perhaps you hit a corner case in some way that destroyed performance in sqlite, but I'd be surprised if those results were representative.

Until there are millions of records grep will win

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