Hi, Xiaoran,
I see. The code is checking if the bits other than rmgr bits, XLR_SPECIAL_REL_UPDATE and XLR_CHECK_CONSISTENCY are used.
Thanks for the explanation.
Steven
I'm confused by the code of XLR_RMGR_INFO_MASK and XLR_INFO_MASK.
According to the definition of masks, the high 4 bits are for rmgr.
/*
* The high 4 bits in xl_info may be used freely by rmgr. The
* XLR_SPECIAL_REL_UPDATE and XLR_CHECK_CONSISTENCY bits can be passed by
* XLogInsert caller. The rest are set internally by XLogInsert.
*/
#define XLR_INFO_MASK 0x0F
#define XLR_RMGR_INFO_MASK 0xF0
However, in function XLogInsert(), there is code:
/*
* The caller can set rmgr bits, XLR_SPECIAL_REL_UPDATE and
* XLR_CHECK_CONSISTENCY; the rest are reserved for use by me.
*/
if ((info & ~(XLR_RMGR_INFO_MASK |
XLR_SPECIAL_REL_UPDATE |
XLR_CHECK_CONSISTENCY)) != 0)
elog(PANIC, "invalid xlog info mask %02X", info);
XLogInsert only allows the rmgr ,XLR_SPECIAL_REL_UPDATE and XLR_CHECK_CONSISTENCY
set in the info.
#define XLR_SPECIAL_REL_UPDATE 0x01
#define XLR_CHECK_CONSISTENCY 0x02
As the XLR_SPECIAL_REL_UPDATE and XLR_CHECK_CONSISTENCY are of the low 4 bits,
the above code is indicating the low 4 bits are for rmgr too?
No, only the high 4 bits are used for RMGR, see the code under directory 'src/backend/access/rmgrdesc'
'XLR_SPECIAL_REL_UPDATE' and 'XLR_CHECK_CONSISTENCY' are not RMGR info, but they
can be passed by XLogInsert caller.
Did I misunderstand something?
Thanks，
Steven
-- Best regards !
Xiaoran Wang
