Replace BackendIds with 0-based ProcNumbers

Now that BackendId was just another index into the proc array, it was
redundant with the 0-based proc numbers used in other places. Replace
all usage of backend IDs with proc numbers.

The only place where the term "backend id" remains is in a few pgstat
functions that expose backend IDs at the SQL level. Those IDs are now
in fact 0-based ProcNumbers too, but the documentation still calls
them "backend ids". That term still seems appropriate to describe what
the numbers are, so I let it be.

One user-visible effect is that pg_temp_0 is now a valid temp schema
name, for backend with ProcNumber 0.

Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/[email protected]

1 files changed, 2 insertions, 2 deletions

diff --git a/doc/src/sgml/xact.sgml b/doc/src/sgml/xact.sgml
index 07b94b11329..3aa7ee1383e 100644
--- a/doc/src/sgml/xact.sgml
+++ b/doc/src/sgml/xact.sgml
@@ -26,10 +26,10 @@
    Every transaction is identified by a unique
    <literal>VirtualTransactionId</literal> (also called
    <literal>virtualXID</literal> or <literal>vxid</literal>), which
-   is comprised of a backend ID (or <literal>backendID</literal>)
+   is comprised of a backend's process number (or <literal>procNumber</literal>)
    and a sequentially-assigned number local to each backend, known as
    <literal>localXID</literal>.  For example, the virtual transaction
-   ID <literal>4/12532</literal> has a <literal>backendID</literal>
+   ID <literal>4/12532</literal> has a <literal>procNumber</literal>
    of <literal>4</literal> and a <literal>localXID</literal> of
    <literal>12532</literal>.
   </para>