Re: code review 9118043: leveldb/db: concatenating and merging iterators. (issue 9118043)

[brad...@golang.org]

https://codereview.appspot.com/9118043/diff/5001/leveldb/db/db.go
File leveldb/db/db.go (right):

https://codereview.appspot.com/9118043/diff/5001/leveldb/db/db.go#newcode259
leveldb/db/db.go:259: // Find the smallest key. We could maintain a heap
instead of doing
I think the heap way is actually simpler than this. And you ultimately
do fewer bytes.Compare operations if this is a heap.

See the latest version of the sstable merging iterator, which uses a
heap efficiently (related:
https://code.google.com/p/go/issues/detail?id=5372) and only calls &
caches the sub-iterator.Key() when the subiterators are initialized or
advance.

https://codereview.appspot.com/9118043/

[nige...@golang.org]

PTAL.

https://codereview.appspot.com/9118043/diff/5001/leveldb/db/db.go
File leveldb/db/db.go (right):

https://codereview.appspot.com/9118043/diff/5001/leveldb/db/db.go#newcode259
leveldb/db/db.go:259: // Find the smallest key. We could maintain a heap
instead of doing

On 2013/05/07 20:09:30, bradfitz wrote:
> I think the heap way is actually simpler than this.

Well, the C++ code just does a linear scan:
https://code.google.com/p/leveldb/source/browse/table/merger.cc#139

https://codereview.appspot.com/9118043/diff/5001/leveldb/db/db_test.go
File leveldb/db/db_test.go (right):

https://codereview.appspot.com/9118043/diff/5001/leveldb/db/db_test.go#newcode143
leveldb/db/db_test.go:143: // TODO: test all sub-iterators being empty.
These TODOs are now done.

https://codereview.appspot.com/9118043/

[brad...@golang.org]

LGTM



https://codereview.appspot.com/9118043/diff/11001/leveldb/db/db_test.go
File leveldb/db/db_test.go (right):

https://codereview.appspot.com/9118043/diff/11001/leveldb/db/db_test.go#newcode117
leveldb/db/db_test.go:117: b := bytes.NewBuffer(nil)
var b bytes.Buffer ?

https://codereview.appspot.com/9118043/diff/11001/leveldb/db/db_test.go#newcode120
leveldb/db/db_test.go:120: fmt.Fprintf(b, "<%s:%s>", iter.Key(),
iter.Value())
&b

https://codereview.appspot.com/9118043/diff/11001/leveldb/db/db_test.go#newcode123
leveldb/db/db_test.go:123: fmt.Fprintf(b, "err=%v", err)
&b

https://codereview.appspot.com/9118043/

[nige...@golang.org]

*** Submitted as
https://code.google.com/p/leveldb-go/source/detail?r=47c9ec4eeea3 ***

leveldb/db: concatenating and merging iterators.

R=bradfitz
CC=golang-dev
https://codereview.appspot.com/9118043


https://codereview.appspot.com/9118043/