# Re: RFC: ship block chain 1-74000 with release tarballs?

Post by: satoshi on November 29, 2010, 08:19:12 PM<br>
Last edit: November 29, 2010, 08:53:12 PM by satoshi

It seems like you're inclined to assume everything is wrong more than is actually so.

Writing the block index is light work. &nbsp;Building the tx index is much more random access per block. &nbsp;I suspect reading all the prev txins is what's slow. &nbsp;Read caching would help that. &nbsp;It's best if the DB does that. &nbsp;Maybe it has a setting for how much cache memory to use.

Quote

> 1) bitcoin should be opening databases, not just environment, at program startup, and closing database at program shutdown.

Already does that. &nbsp;See CDB. &nbsp;The lifetime of the (for instance) CTxDB object is only to support database transactions and to know if anything is still using the database at shutdown.

Quote

> And, additionally, bitcoin forces a database checkpoint, pushing all transactions from log into main database.

If it was doing that it would be much slower. &nbsp;It's supposed to be only once a minute or 500 blocks:

&nbsp;&nbsp;&nbsp;&nbsp;if (strFile == "blkindex.dat" && IsInitialBlockDownload() && nBestHeight % 500 != 0)<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;nMinutes = 1;<br>
&nbsp;&nbsp;&nbsp;&nbsp;dbenv.txn_checkpoint(0, nMinutes, 0);

Probably should add this:<br>
&nbsp;&nbsp;&nbsp;&nbsp;if (!fReadOnly)<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dbenv.txn_checkpoint(0, nMinutes, 0);

Quote

> 2) For the initial block download, txn commit should occur once every N records, not every record. &nbsp;I suggest N=1000.

Does transaction commit imply flush? &nbsp;That seems surprising to me. &nbsp;I assume a database op wrapped in a transaction would be logged like any other database op. &nbsp;Many database applications need to wrap almost every pair of ops in a transaction, such as moving money from one account to another. (debit a, credit b) &nbsp;I can't imagine they're required to batch all their stuff up themselves.

In the following cases, would case 1 flush once and case 2 flush twice?

case 1:<br>
write<br>
write<br>
write<br>
write<br>
checkpoint

case 2:<br>
begin transaction<br>
write<br>
write<br>
commit transaction<br>
begin transaction<br>
write<br>
write<br>
commit transaction<br>
checkpoint

Contorting our database usage will not be the right approach. &nbsp;It's going to be BDB settings and caching.

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