headers
Dave Smith | 3 Apr 2012 18:46
Gravatar

Re: RFC: bloom filter (and generalized summary) support in leveldb

Hi Sanjay,

Any update on the status of the bloom filter/summarization support?
Any branches you'd like tested/exercised?

Thanks,

D.

On Wed, Feb 29, 2012 at 4:20 PM, Sanjay Ghemawat <sanjay <at> google.com> wrote:
>> If I understand the proposal aright, I believe that the Summarizer
>> will only be deserialized when the index block (or metaindex block) is
>> deserialized for the whole SST. Once that block is cached, you
>> shouldn't have to worry about that cost again, unless you have
>> insufficient room in your cache.
>
> Right, except that there should be no deserialization step.   The summary
> should be preformatted so it can be accessed quickly.
>
>> This does raise a random question -- would it be good to have a
>> independent cache for index blocks?
>
> This can be achieved by setting "max_open_files". These many sstable files
> are kept open and their index blocks (and associated summaries and bloom
> filters in the future) will be kept cached in memory. So if you are getting
> too many disk seeks to fetch index blocks, you can fix that by adjusting
> max_open_files. It might be worthwhile to have independent controls for
> max-open-files and index block caching, but I think it is not very urgent or
> important to do that right now.
(Continue reading)

Permalink | Reply | 5 comments |
headers
leveldb | 4 Apr 2012 11:38

Issue 81 in leveldb: Compilation issues using Cygwin under Windows 7

Status: New
Owner: ----
Labels: Type-Defect Priority-Medium

New issue 81 by luke.gla... <at> gmail.com: Compilation issues using Cygwin  
under Windows 7
http://code.google.com/p/leveldb/issues/detail?id=81

What steps will reproduce the problem?

1. Install Cygwin on a Windows 7 system
2. Checkout/create an Android application under $APP so that  
AndroidManifest.xml is visible in that directory.
3. Follow the installation instructions (download NDK to $NDK, levelDB to  
$APP/jni so that Android.mk is directly visible in that directory).

4. in Cygwin, cd to $APP
5. run $NDK/ndk-build

What is the expected output? What do you see instead?

Expected: some proper output somewhere around $APP or $APP/jni

Happened: Compilation errors (small sample below)

Compile++ thumb  : leveldb <= builder.cc

In file included from jni/./db/builder.cc:5:
jni/db/builder.h:8:28: error: leveldb/status.h: No such file or directory
In file included from jni/./db/builder.cc:7:
(Continue reading)

Permalink | Reply | 2 comments |
headers
leveldb | 4 Apr 2012 14:45

Re: Issue 81 in leveldb: Compilation issues using Cygwin under Windows 7


Comment #1 on issue 81 by luke.gla... <at> gmail.com: Compilation issues using  
Cygwin under Windows 7
http://code.google.com/p/leveldb/issues/detail?id=81

This issue can be deleted, I resolved it by checking out the latest version  
of the repository and switching to the android-branch.
Permalink | Reply | 0 comments |
headers
leveldb | 4 Apr 2012 15:45

Re: Issue 81 in leveldb: Compilation issues using Cygwin under Windows 7

Updates:
	Status: WontFix

Comment #2 on issue 81 by tfar... <at> chromium.org: Compilation issues using  
Cygwin under Windows 7
http://code.google.com/p/leveldb/issues/detail?id=81

(No comment was entered for this change.)
Permalink | Reply | 0 comments |
headers
leveldb | 4 Apr 2012 16:26

Re: Issue 64 in leveldb: Android Native Calls


Comment #1 on issue 64 by luke.gla... <at> gmail.com: Android Native Calls
http://code.google.com/p/leveldb/issues/detail?id=64

Here's what I have found out so far:

No code in the android-branch of the repository seems to have any of the  
extravagant function headers like the example over at  
http://altdevblogaday.com/2011/12/09/running-native-code-on-android-part-1/  
shows:

Java:
public static native int ComputeSum(int a, int b);

C-code:
JNIEXPORT jint JNICALL  
Java_com_adbad_jnitest_MyJNILibrary_ComputeSum(JNIEnv * env, jobject obj,  
jint a, jint b)
{
    return (a + b);
}

Since there were no java-files included in the Android branch and no  
JNI-headers are present there's not much for us to go on.
Can you please document the Java API for your code? This issue has been  
unresolved for over four months.
Permalink | Reply | 0 comments |
headers
casablanca | 5 Apr 2012 16:58
Picon

need help to start to play around with leveldb

Hey all,

I am a student and I wanted to just learn how to install this on my
system and understand some examples.
I am very new to databases and SQL havent had much of an exposure
before. But I would like to learn to improve myself.
I would greatly appreciate if any one can guide me about this.

Thanks!
Permalink | Reply | 0 comments |
headers
Sanjay Ghemawat | 5 Apr 2012 18:51
Picon
Favicon

Removing Table/TableBuilder from public leveldb API

A heads up: we plan to remove include/leveldb/table.h and
include/leveldb/table_builder.h.

These header files define the Table and TableBuilder classes. They are used
inside leveldb's implementation. The functionality they provide is not
useful for most leveldb users. It was a mistake to make these classes
public. We will rectify this by moving these classes from include/leveldb to
an internal directory.  Some reasons for this move:

(1) We want to make some changes to these classes to support things needed
by the leveldb implementation (like bloom filter support).

(2) There are potential size and speed that can be made to the Table
implementation if we only need to support its use inside leveldb.

(3) The public interface to leveldb will become simpler.  This will
especially help new users exploring the public include directory trying to
figure out what they should use.

(4) We will remove a rarely used and half-supported (no documentation,
no C binding, etc.) portion of the public API.

Apologies if this will break your code. Please let us know if you are
actually using the Table functionality directly. Though our response might
be to ask you to fork the Table code for your needs.
Permalink | Reply | 1 comment |
headers
Sanjay Ghemawat | 6 Apr 2012 01:21
Picon
Favicon

Re: RFC: bloom filter (and generalized summary) support in leveldb

On Tue, Apr 3, 2012 at 9:46 AM, Dave Smith <dizzyd <at> dizzyd.com> wrote:
> Hi Sanjay,
>
> Any update on the status of the bloom filter/summarization support?
> Any branches you'd like tested/exercised?

Sorry, there are no branches that can be tested yet.  I have been
flip-flopping trying to decide between a couple of different types
of interfaces.
Permalink | Reply | 4 comments |
headers
Shrirang | 6 Apr 2012 07:52
Picon

Leveldb caching

Hello,

What is the limit of data that leveldb library caches?

When one opens the leveldb, he gets the leveldb-ptr. If this "ptr" is
deleted then leveldb doesn't cache any data. But if the "ptr" is held
within the process, then the process-memory increases. More operations
(write / read) you do through that "ptr", and process-memory increases
more.

If one writes some data through this "ptr" and after that removes all
the DB-files from the disk and then try to read back the data from
same "ptr" then it is successful. This shows that leveldb doesn't
always read data from the disk; but it also has its own cache.

I want to know the limit for this caching.
What will be the maximum memory-increase that can be seen in the
process?
Does this caching works per database basis or there is a common limit
for all datatabases?

Thanks,
Shrirang
Permalink | Reply | 0 comments |
headers
leveldb | 7 Apr 2012 15:55

Issue 82 in leveldb: make php binding for leveldb

Status: New
Owner: ----
Labels: Type-Defect Priority-Medium

New issue 82 by realt5... <at> gmail.com: make php binding for leveldb
http://code.google.com/p/leveldb/issues/detail?id=82

One exists (https://github.com/arraypad/php-leveldb)
but does not implement all features and is not active anymore.
Permalink | Reply | 5 comments |

Gmane