[Postgres-xl-bugs] postgres-xl HA with pgpool and stream replication?

Koichi Suzuki koichi.dbms at gmail.com
Mon Jun 29 19:57:24 PDT 2015


You need to use synchronous replication not to lose any updates.
Synchronous replication is slow and you can configure only one synchronous
slave for a node.   When synchronous slave crashes or stops, the master is
blocked unless the master cuts out the synchronous slave.

Pgxc_ctl does some of this work.

Regards;

---
Koichi Suzuki

2015-06-30 11:26 GMT+09:00 Lucky Haryadi <lucky at equnix.co.id>:

> Hi, Kaijiang
>
> Currently I'm doing some experiments with XL using hot standby replication.
> The configuration is like this:
>
>  ---------------------------------------------------------------------
>                          | Master Coordinator ----- (Stream Reps) ------>
> Slave Coordinator  |
>
>  ---------------------------------------------------------------------
>                                        |
>    |
>                                        |
>    |
> ----------------------------------------------
>  -----------------------------------------------
> | Master Data Node 1 -----> Slave Data Node 1|            | Master Data
> Node 2 -----> Slave Data Node 2 |
> ----------------------------------------------
>  -----------------------------------------------
>
> And I build my own HA scripts, using simple bash script to do heartbeat
> between Master-Slave pair and do the failover, like takeover the floating
> IP and promoting Slave to Master.
>
> The whole configuration was running well on normal condition, no
> transaction, no action at all to the configuration.
> And I did some insertion, like 10million data (using generate_series) to
> one table, and all was perfect. The data was distributed normally on all
> Data Nodes, including the Slave ones.
>
> So on next experiment, I tried to forcing shutdown on one of the data node
> on normal condition (without transaction), failover was successful.
> Insertion after failover was also successful.
>
> And I did the next experiment, forcing shutdown on one data node while
> inserting bunch of data (for example after 30 seconds).
> The failover was successful, slave data node promoted to master, but some
> weird cases happened:
>
> 1. The inserted table on the promoted slave is gone.
> 2. Data count in the table on other data node (which still on normal
> Master-Slave condition) is zero.
> 3. Total data count when I did query via Coordinator is zero.
>
> Currently I'm still investigating those cases by doing the same experiment
> and verbosing the log.
>
> Will come to you again after I get some updates.
>
> Regards,
>
> Lucky Haryadi
> Equnix Business Solutions, PT
> (An Open Source and Open Mind Company)
>
> On Mon, Jun 29, 2015 at 9:38 PM, Kaijiang Chen <chenkaijiang at gmail.com>
>  wrote:
>
>> Hi, all, does postgres-XL support stream replication (treat the XL as a
>> single DB and replicate the entire DB in another XL for HA)?
>>
>> Can I treat the XL as a single DB and build an HA environment with
>> PGPool?
>>
>> It looks like that XL doesn't support some HA features of postgreSQL. Is
>> there any introduction to good practice of XL HA?
>>
>> Best Regards,
>> Kaijiang
>>
>>
>>
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