diff options
Diffstat (limited to 'src/include')
| -rw-r--r-- | src/include/postmaster/postmaster.h | 12 | ||||
| -rw-r--r-- | src/include/storage/procnumber.h | 13 |
2 files changed, 13 insertions, 12 deletions
diff --git a/src/include/postmaster/postmaster.h b/src/include/postmaster/postmaster.h index d8a9f14b3b8..b6a3f275a1b 100644 --- a/src/include/postmaster/postmaster.h +++ b/src/include/postmaster/postmaster.h @@ -127,18 +127,6 @@ extern bool ReleasePostmasterChildSlot(PMChild *pmchild); extern PMChild *FindPostmasterChildByPid(int pid); /* - * Note: MAX_BACKENDS is limited to 2^18-1 because that's the width reserved - * for buffer references in buf_internals.h. This limitation could be lifted - * by using a 64bit state; but it's unlikely to be worthwhile as 2^18-1 - * backends exceed currently realistic configurations. Even if that limitation - * were removed, we still could not a) exceed 2^23-1 because inval.c stores - * the ProcNumber as a 3-byte signed integer, b) INT_MAX/4 because some places - * compute 4*MaxBackends without any overflow check. This is rechecked in the - * relevant GUC check hooks and in RegisterBackgroundWorker(). - */ -#define MAX_BACKENDS 0x3FFFF - -/* * These values correspond to the special must-be-first options for dispatching * to various subprograms. parse_dispatch_option() can be used to convert an * option name to one of these values. diff --git a/src/include/storage/procnumber.h b/src/include/storage/procnumber.h index 7cf981ab673..75c2c7a17c0 100644 --- a/src/include/storage/procnumber.h +++ b/src/include/storage/procnumber.h @@ -26,6 +26,19 @@ typedef int ProcNumber; #define INVALID_PROC_NUMBER (-1) /* + * Note: MAX_BACKENDS_BITS is 18 as that is the space available for buffer + * refcounts in buf_internals.h. This limitation could be lifted by using a + * 64bit state; but it's unlikely to be worthwhile as 2^18-1 backends exceed + * currently realistic configurations. Even if that limitation were removed, + * we still could not a) exceed 2^23-1 because inval.c stores the ProcNumber + * as a 3-byte signed integer, b) INT_MAX/4 because some places compute + * 4*MaxBackends without any overflow check. This is rechecked in the + * relevant GUC check hooks and in RegisterBackgroundWorker(). + */ +#define MAX_BACKENDS_BITS 18 +#define MAX_BACKENDS ((1U << MAX_BACKENDS_BITS)-1) + +/* * Proc number of this backend (same as GetNumberFromPGProc(MyProc)) */ extern PGDLLIMPORT ProcNumber MyProcNumber; |