[Herddb-dev] Question file storage.

Enrico Olivelli eolivelli at gmail.com
Wed Jun 12 23:34:17 CEST 2019


Il giorno mer 12 giu 2019 alle ore 22:04 Amit Chavan <achavan1 at gmail.com>
ha scritto:

> Thanks. Followup question. How do I replay the transaction log to recreate
> the data?
> In order for the data to be replayed on a new server, you will also
> require the table metadata(schema)? Is there a command line tool to do
> that?
>

I am not sure I undestand.

If you want to clone a database and you can stop the server just:
- stop the server
- copy server data to another machine
- start the server


If you want to perform a backup/restore of a tablespace you have to use
herddb-cli.sh, I can't recall the options but you will find it easily.

If you want to have more copies of the data, realtime synced, you have to
use the cluster mode, in which you have a cluster of servers and you assign
one or more "replicas" to a tablespace, and this is of course the most cool
feature of HerdDB.

hope that helps
Enrico






>
> On Wed, Jun 12, 2019 at 3:00 AM <herddb-dev-request at lists.herddb.org>
> wrote:
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>> Today's Topics:
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>>    1. Question file storage. (Amit Chavan)
>>    2. Re: Question file storage. (Enrico Olivelli)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Tue, 11 Jun 2019 21:19:19 -0700
>> From: Amit Chavan <achavan1 at gmail.com>
>> To: herddb-dev at lists.herddb.org
>> Subject: [Herddb-dev] Question file storage.
>> Message-ID:
>>         <CADsOBjM-WjEZms1-ddY9RHs=8fy9GkNcXY=bP64sG-bTdsV2=
>> Q at mail.gmail.com>
>> Content-Type: text/plain; charset="utf-8"
>>
>> Hello,
>>
>> I was playing around with herddb to do some testing today. I create a very
>> simple table ./herddb-cli.sh -q "CREATE TABLE amit(id int primary key,
>> name
>> string)". I see table meta data file, txlog file etc created for this
>> table. I also inserted 2 to 3 rows into this table and I am able to see
>> the
>> txlog being appended by the transaction. What I don't see is the data
>> actually being written to the disk for the table. The directory
>>
>> *dbdata/data/20017d0222784757b504d0a157c59333.tablespace/fa077872-98c2-495d-8891-75936baa3a40.table
>> *is empty. When does the in-memory data get written to the disk? Is there
>> a
>> setting or does it occur during checkpoint ?
>>
>> Thanks,
>> Amit
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>> ------------------------------
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>> Message: 2
>> Date: Wed, 12 Jun 2019 08:45:42 +0200
>> From: Enrico Olivelli <eolivelli at gmail.com>
>> To: Herddb developers <herddb-dev at lists.herddb.org>
>> Subject: Re: [Herddb-dev] Question file storage.
>> Message-ID:
>>         <CACcefgdw2eeLEANSeb=
>> x-_A-COF7MhwZoD2cMunSJwzv3RxVSA at mail.gmail.com>
>> Content-Type: text/plain; charset="utf-8"
>>
>> Amit,
>>
>> Il mer 12 giu 2019, 06:20 Amit Chavan <achavan1 at gmail.com> ha scritto:
>>
>> > Hello,
>> >
>> > I was playing around with herddb to do some testing today. I create a
>> very
>> > simple table ./herddb-cli.sh -q "CREATE TABLE amit(id int primary key,
>> name
>> > string)". I see table meta data file, txlog file etc created for this
>> > table. I also inserted 2 to 3 rows into this table and I am able to see
>> the
>> > txlog being appended by the transaction. What I don't see is the data
>> > actually being written to the disk for the table. The directory
>> *dbdata/data/20017d0222784757b504d0a157c59333.tablespace/fa077872-98c2-495d-8891-75936baa3a40.table
>> > *is empty. When does the in-memory data get written to the disk? Is
>> there
>> > a setting or does it occur during checkpoint ?
>> >
>>
>> Data is written to the journal/commit log.
>> Data pages are swapped to disk:
>> - at checkpoint
>> - when the system is out of memory
>>
>> Enrico
>>
>> >
>> > Thanks,
>> > Amit
>> > _______________________________________________
>> > herddb-dev mailing list
>> > herddb-dev at lists.herddb.org
>> > http://lists.herddb.org/mailman/listinfo/herddb-dev
>> >
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