Re: Disable WAL completely - Performance and Persistency research

Hi Michael,

Sorry for the delay,
The answer is yes,

I tried 2 things so far:
1. As I understand:

*XLogRecPtr*
*XLogInsert(RmgrId rmid, uint8 info)*

is the primary insert function in xloginsert.c.
I tried commenting the following line at this function, so I can return a
phony pointer every time the function is called, just as in bootstrap mode.

*if (IsBootstrapProcessingMode() && rmid != RM_XLOG_ID)*

2. At xlog.c, CopyXLogRecordToWAL(int write_len, bool isLogSwitch,
XLogRecData *rdata,
XLogRecPtr StartPos, XLogRecPtr EndPos), Commenting the memcpy syscall:

...

memcpy(currpos, rdata_data, rdata_len);

...

BUT, both options are not good, as they are stopping me from even running i
*nitdb.*

Maybe someone have a lead regarding changes to be done at xlog.c:

*XLogInsertRecord(XLogRecData *rdata, XLogRecPtr fpw_lsn)*

Any other lead regarding xloginsert.c is welcomed as well.

Regards,

Netanel

On Thu, Jul 7, 2016 at 4:17 PM, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
wrote:

> On Thu, Jul 7, 2016 at 5:01 PM, Netanel Katzburg <netanel10k(at)gmail(dot)com>
> wrote:
> > 1. Disable the WAL by not writing anything to the xlog directory. I don't
> > care about recovery/fault tolerance or PITR/ replication etc at the
> moment.
> > I'm aware that the WAL and checkpoint are bind in many ways and are
> crucial
> > for PG core features.
> > Any guidance on how to do so would be appreciated :)
>
> WAL insertion routines are in xloginsert.c. Did you try to play with those?
> --
> Michael
>